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Characterization of Pure Ductal Carcinoma In Situ on Dynamic Contrast-Enhanced MR Imaging: Do Nonhigh Grade and High Grade Show Different Imaging Features?

Characterization of Pure Ductal Carcinoma In Situ on Dynamic Contrast-Enhanced MR Imaging: Do... Hindawi Publishing Corporation Journal of Oncology Volume 2010, Article ID 431341, 9 pages doi:10.1155/2010/431341 Clinical Study Characterization of Pure Ductal Carcinoma In Situ on Dynamic Contrast-Enhanced MR Imaging: Do Nonhigh Grade and High Grade Show Different Imaging Features? 1 2, 3 2 2 4 Siwa Chan, Jeon-Hor Chen, Garima Agrawal, Muqing Lin, Rita S. Mehta, 5 2 2 Philip M. Carpenter, Orhan Nalcioglu, and Min-Ying Su Department of Radiology, Taichung Veterans General Hospital, Taichung 404, Taiwan Tu and Yuen Center for Functional Onco-Imaging and Department of Radiological Science, University of California, Irvine, Ca 92697, USA Department of Radiology, China Medical University Hospital, Taichung 404, Taiwan Department of Medicine, University of California, Irvine, Ca 92868, USA Department of Pathology, University of California, Irvine, Ca 92868, USA Correspondence should be addressed to Jeon-Hor Chen, jeonhc@uci.edu Received 30 April 2010; Revised 4 July 2010; Accepted 5 August 2010 Academic Editor: Aysegula A. Sahin Copyright © 2010 Siwa Chan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To characterize imaging features of pure DCIS on dynamic contrast-enhanced MR imaging (DCE-MRI), 31 consecutive patients (37-81 years old, mean 56), including 2 Grade I, 16 Grade II, and 13 Grade III, were studied. MR images were reviewed retrospectively and the morphological appearances and kinetic features of breast lesions were categorized according to the ACR BI-RADS breast MRI lexicon. DCE-MRI was a sensitive imaging modality in detecting pure DCIS. MR imaging showed enhancing lesions in 29/31 (94%) cases. Pure DCIS appeared as mass type or non-mass lesions on MRI with nearly equal frequency. The 29 MR detected lesions include 15 mass lesions (52%), and 14 lesions showing non-mass-like lesions (48%). For the mass lesions, the most frequent presentations were irregular shape (50%), irregular margin (50%) and heterogeneous enhancement (67%). For the non-mass-like lesions, the clumped internal enhancement pattern was the dominate feature, seen in 9/14 cases (64%). Regarding enhancement kinetic curve, 21/29 (78%) lesions showed suspicious malignant type kinetics. No significant difference was found in morphology (P> .05), tumor size (P = 0.21), and kinetic characteristics (P = .38) between non-high grade (I+II) and high-grade (III) pure DCIS. 1. Introduction cancer, with the trend still increasing [4]. In mammogra- phy, DCIS most frequently presents as microcalcifications, Ductal Carcinoma In Situ (DCIS) is characterized by accounting for about 85%−90% of diagnosed cases. An proliferation of malignant cells confined by the basement accurate preoperative staging is very important for treatment membranes of ductal structures, without evidence of extra- planning of DCIS. Although mammography has been the ductal invasion [1]. DCIS comprises different subtypes mainstay for diagnosis of DCIS, it has limitations in defining with heterogeneous proliferative disease processes and varies the extension and the margin, especially in patients without in architecture, imaging features, and clinical outcome. microcalcifications or in those with dense breasts or breast Although the progression of DCIS is not fully understood, implants. Furthermore, there is a tendency to underestimate it is known that untreated DCIS is likely to progress to the tumor size of DCIS on mammography [5–7]. Positive invasive cancer within 10 years of diagnosis. Therefore, DCIS surgical margin is known as an independent risk factor for is considered a preinvasive form of invasive breast cancer that localrecurrence[8–10]. requires immediate treatment [2, 3]. Dynamic contrast-enhanced MRI (DCE-MRI) has been With the widespread use of screening mammography, proven more sensitive than mammography for detecting DCIS now accounts for 15%−20% of all newly detected breast breast cancer in young women with a high risk of developing 2 Journal of Oncology breast cancer [11–13]. In many instances, DCE-MRI can precontrast imaging and dynamic contrast-enhanced imag- reveal early stage breast cancer, including DCIS and DCIS ing. After setting the IV line, the patient was placed into with small invasive carcinomas, which are mammographi- the scanner in the prone position. The breasts were gently cally, sonographically, and clinically occult. In addition to cushioned inside the coil to reduce motion. The localizer screening, breast MR can also be used for staging purposes scan was first taken to define the location of breasts. Then a to better characterize the disease extent and the presence sagittal view unilateral T1-weighted precontrast images were of multifocal multicentric lesions, which can impact on acquired from the breast of concern, using a spin echo pulse treatment planning and the subsequent management. sequence with TR = 1000 ms, TE = 12 ms, and FOV = 20 cm, Imaging characterization of patients with mixed cohort and matrix size = 256 × 256. Following this, a 3D SPGR of pure DCIS and DCIS with invasive components [14– (RF-FAST) pulse sequence with 16 frames (repetitions) 17] and patients with merely pure DCIS [18–25]onDCE- was prescribed for bilateral dynamic imaging. Thirty-two MRI has been reported before. In a study of 167 patients, axial slices with 4 mm thickness were used to cover both Kuhl et al. found that mammography only diagnosed 56% breasts. The imaging parameters were TR = 8.1 ms, TE = pure DCIS preoperatively, while MRI achieved a diagnostic 4.0 ms, flip angle = 20 ,matrixsize = 256 × 128, FOV = rate of 92%. For 89 high-grade lesions, MRI detected 87 32−38 cm. The scan time was 42 sec per acquisition. The lesions (98%) while mammography only diagnosed 52% of sequence was repeated 16 times for dynamic acquisitions, lesions [23]. Nevertheless, consensus regarding how MRI four precontrast, and 12 postcontrast sets. The contrast agent can be used to aid in management of pure DCIS has not (Omniscan, 1 cc/10 lbs body weight) was manually injected been reached yet. Given the recent evidence that additional at the beginning of the 5th acquisition and was timed to diseases diagnosed by preoperative MRI often led to more finish in 12 seconds to make the bolus length consistent for aggressive treatment yet did not improve the treatment all patients. Immediately following the contrast, 10 cc saline outcome [26, 27], continuing exploration of the role of breast was injected to flush in all contrast medium. MRI for the diagnosis of DCIS is needed. The purpose of this retrospective study was to character- 2.3. Enhancement Kinetic Time Course. All images were ize the morphology and enhancement kinetic pattern of pure transferred to a PC for analysis. The subtraction images at DCIS on DCE-MRI. Since high-grade DCIS is associated 1-minute postinjection were generated by subtracting the with a greater risk of local recurrence and progression to precontrast images acquired in Frame number 3 from the invasive breast cancer [28–30], it would be very helpful if the postcontrast-enhanced images acquired in Frame number 6. high-grade and low-grade DCIS could be differentiated on The maximum intensity projections (MIPs) were also gener- imaging. In this paper, the MRI features of DCIS between ated from the subtraction images to help identify the lesion. high-grade (Grade III) and non-high-grade (including low The enhancement kinetic was analyzed from manually Grade I and intermediate Grade II) DCIS based on the van selected ROI (Region of Interest) based on the subtraction Nuys classification [31] were compared. images at 1-minute post-injection. The enhanced tumor area was outlined on each imaging slice covering the lesion by an experienced breast radiologist; then a mean signal intensity 2. Materials and Methods time course from all 16 time frames was obtained. The 2.1. Patients. A total of 34 consecutive patients with percentenhancement time course wascalculatedbyfirstsub- histological-proven pure DCIS (without any microinvasion) tracting the mean precontrast signal intensity (mean of first were identified from our breast MRI database collected 4 frames) from each of the subsequent 12 postcontrast signal from 2002 to 2006. These patients came to our center to intensities and then normalized by the mean precontrast participate in a breast MRI research study due to suspicious signal intensity ×100%. lesions found in mammography, sonography, or physical examination. The medical records, breast MRI images, and 2.4. MR Imaging Feature Analysis. Morphological appear- mammogram reports (if available) were reviewed retrospec- ances and enhancement kinetic features of lesions shown on tively. Among these 34 patients, three patients had received MRI were categorized according to the ACR Breast Imaging surgical excision biopsy before MR imaging, and they were Reporting and Data System (BI-RADS) breast MRI lexicon excluded in the analysis. The remaining 31 patients were [30]. The features were evaluated by 2 radiologists (with 4 37−81 years old (mean 56). The final diagnosis of pure DCIS and 5 years of experience in reading breast MRI) separately. was obtained from pathological examination of mastectomy For cases with different results, they were discussed to (N = 21) and lumpectomy (N = 10) specimens. Screening reach a consensus. Based on the enhancement of lesions, mammography reports were available for 22 patients. This the morphology was first separated into mass lesions and study was approved by the institutional review board, and Nonmass-like lesions. Based on the lesion size, the mass informed consents were obtained from all patients. type can be further separated into single focus/multiple foci (<5 mm) and mass (≥5 mm). Then for mass lesions 2.2. MR Imaging Protocol. The MRI study was performed other characteristics such as shape, margin, and internal using a 1.5 T Phillips Eclipse MR scanner with a standard enhancement patterns were evaluated. The Nonmass-like bilateral breast coil (Philips Medical Systems, Cleveland, lesions were described by the type of enhancements (diffuse, Ohio). The imaging protocol consisted of high-resolution regional, segmental, focal, ductal, linear) and the internal Journal of Oncology 3 enhancement patterns (punctate/stippled, clumped, and Table 1: Pathological types and grades of 31 pure DCIS lesions. heterogeneous). The tumor size was measured as the longest Grade I Grade II Grade III Total diameter on the maximum intensity projection (MIP) of Noncomedo type 2 11 6 19 subtraction image. Comedo type 0 5 7 12 The enhancement kinetics was divided into two phases: the initial enhancement phase, defined as enhancement Total 2 16 13 31 patterns within the first 2 minutes or before the curve starts to change, and the delayed phase, defined as enhancement pattern after 2 minutes or after the curve starts to change. non-high grade DCIS and 2.2± 1.3 cm for high-grade DCIS, The initial enhancement phase was classified as fast, medium, not significantly different (P = .21). and slow. The delayed enhancement phase was described For the two false negative cases, in mammography, one as persistent, plateau, and washout pattern. When the case was occult, and the other was undetermined (i.e., needed enhancement kinetics showed a rapid initial enhancement additional imaging evaluation). The mammographically followed by washout or reaching to a plateau in the delayed occult case received ultrasound exam and found a suspicious phase, it was determined as suspicious of malignancy. hypoechoic mass in the left breast. After needle biopsy con- firming malignancy, the patient received lumpectomy, and a pure DCIS of 1.4 cm was found. The mammographically 2.5. Histopathology. All cases are pure DCIS without pres- undetermined case had a palpable nodule in her left breast. ence of microinvasion. The pathological diagnosis was This patient was diagnosed with DCIS in the right breast 2 evaluated based on the van Nuys system [29]. DCIS was years ago and had already received right mastectomy. She classified according to the nuclear grade (non-high grade decided to receive left mastectomy, and a pure high grade versus high grade) and the morphologic subtype (comedo DCIS of 1.1 cm was found. and noncomedo). Grade-I (low grade) and Grade-II (inter- mediate grade) were categorized as non-high grade, and grade-III was the high-grade. 3.2.2. Mass Lesions. Among the 15 mass lesions, 9 cases were non-high grade, and 6 were high grade. For the 14 Nonmass- like lesions, 9 lesions were non-high grade, and 5 cases were 2.6. Statistical Analysis. For statistical analysis, Fisher’s exact high grade (P = .26). The shape, margin, and internal test was used to examine the significant difference between enhancement patterns were evaluated in 12 mass lesions non-high grade DCIS and high grade DCIS. A P-value < .05 that were ≥5 mm. The most frequently seen features were was considered statistically significant. irregular shape (50%), spiculated/irregular margin (92%), and heterogeneous enhancement (67%) (Table 3). There was 3. Results no significant difference in the MR morphology pattern between the non-high-grade and high-grade mass type DCIS 3.1. Patient and Tumor Characteristics. According to the lesions. Three case examples are shown in Figure 1 (low nuclear grading system, 2 patients had Grade-I, 16 patients grade), Figure 3 (intermediate grade), and Figure 4 (high had Grade-II, and 13 patients had Grade-III, all together grade). 18 non-high grade and 13 high grade. The mean age for non-high grade DCIS was 52 years old and 57 years old for 3.2.3. Nonmass-Like Lesions. Of 14 Nonmass lesions, 4 high-grade DCIS (P = .27). The comedo type was noted lesions showed regional enhancement (28%), 3 showed duc- in 12 patients (7 high grade and 5 non-high grade), and tal (22%), and 3 showed focal (22%) enhancements. Figure 2 the noncomedo type was noted in 19 patients (6 high grade shows one case example with multiple foci (intermediate and 13 non-high grade) (Table 1). There was no significant grade). Internal enhancement pattern was dominated by the difference in the histological comedo or noncomedo subtype clumped pattern (Figure 5, high grade) (9/14, 64%) followed between the non-high grade and high grade DCIS (P> .05). by the heterogeneous enhancement pattern (4/14, 29%) (Table 4). 3.2. MR Morphology Analysis 3.2.1. Tumor Size and Mass versus Nonmass Morphology. 3.3. MR Enhancement Kinetic Curve Assessment. The MR imaging showed contrast-enhanced lesions in 29/31 enhancement kinetic curves were measured from 27 lesions. (94%) cases. Two cases of high-grade DCIS with noncomedo Two Grade-II lesions had severe motion artifacts due to morphology were not detected by MRI and were false patient’s movement during the delayed phase, and the negative diagnosis. The imaging features of these 29 cases are enhancement kinetic curves could not be reliably measured. summarized in Table 2, and 5 case examples are shown in The early postcontrast subtraction images had good quality, Figures 1−5. Among these 29 cases, mass lesions were seen in and the morphological features of these two lesions could 15 cases (52%) including 12 masses and 3 focus/foci lesions be evaluated. Twenty-one lesions (21/27, 78%) showed and Nonmass-like lesions in 14 cases (48%). Two cases were the suspicious malignant type enhancement kinetics with multifoci (Figures 2 and 5), and the size was not measured. a rapid initial enhancement followed by plateau (Figures For the remaining cases, the size ranged from 0.4 to 5 cm with 1 and 5) or washout (Figures 2−4), including 1/2 Grade-I the mean of 1.9± 1.2cm. The mean size was 1.6± 1.2cm for lesion, 12/14 Grade-II lesions, and 8/11 Grade-III lesions. 4 Journal of Oncology Table 2: MR imaging features of 29 pure DCIS lesions detected by MRI. Grade I Grade II Grade III Total % Morphology (N = 29) Focus/Foci (N = 3) 0 3 0 3/29 (11%) Mass (N = 12) 1 5 6 12/29 (41%) Nonmass (N = 14) 1 8 5 14/29 (48%) Enhancement kinetics (N = 27) Fast washout (N = 16) 1 8 7 16/27 (59%) Fast plateau (N = 5) 0 4 1 5/27 (19%) Continuous enhancement (N = 6) 1 2 3 6/27 (22%) Table 3: Morphological characteristics of 12 mass lesions. MRI diagnosed 27 as suspicious of malignancy, with the sensitivity of 87% (27/31). Grade I Grade II Grade III Total Margin 3.4. Correlation of MRI and Mammography Findings. Cor- Spiculated 0 4 1 5 (42%) relation between screening mammogram and MR Imaging Irregular 1 1 4 6 (50%) was performed in 22 patients whose mammography reports Smooth 0 0 1 1 (8%) were available. Sixteen lesions (16/22, 73%) were classified Shape as BI-RADS 4 or 5, as “suspicious” or “highly suspicious Irregular 1 2 3 6 (50%) of malignancy” on mammography. Five of 22 patients were Lobular 0 2 1 3 (25%) classified as BI-RADS category 1 (normal mammogram) and one patient as BI-RADS category-0 (need additional Round/Ovoid 0 1 2 3 (25%) imaging evaluation). On MRI, four of 5 patients with normal Internal Enhancement mammogram were correctly diagnosed as suspicious of Rim 0 0 1 1 (8%) malignancy, showing malignant type enhancement kinetics Homogenous 0 1 2 3 (25%) (rapid enhancement followed by washout or plateau) and/or Heterogeneous 1 4 3 8 (67%) the morphological appearance (irregular shape and spicu- There was no significant difference of the morphology pattern for mass type lated/irregular margin). lesion between the non-high-grade (I + II) and high-grade (III) pure DCIS. 4. Discussion Table 4: Morphological characteristics of 14 Nonmass lesions. Mammography may miss DCIS that does not present certain Grade I Grade II Grade III Total suspicious patterns of microcalcifications, and MRI may have Enhancement Type a complementary role in diagnosis of these lesions. Most Diffuse 0 0 1 1 (7%) of the MR imaging studies of DCIS analyzed mixed patient Regional 1 2 1 4 (28%) cohort of pure DCIS and DCIS with invasive components. Several studies reported the MR kinetic and morphologic Segmental 0 1 1 2 (14%) appearance of pure DCIS correlated with histopathology Focal 0 3 0 3 (22%) findings [18–25]. In a study by Kuhl et al., only 56% pure Ductal 0 1 2 3 (22%) DCIS was detected by mammography, while MRI could Linear 0 1 0 1 (7%) detect more than 90% [23]. In another study of 33 pure DCIS Enhancement Pattern patients by Vag et al. [24] the sensitivity of mammography Punctate/stippled 0 0 1 1 (7%) and MRI was 64% and 88%, respectively. In this study, we Clumped 1 5 3 9 (64%) detected 29/31 (94%) enhancing lesions and diagnosed 27/31 Heterogeneous 0 3 1 4 (29%) (87%) as suspicious of malignancy. Of the 22 patients whose There was no significant difference of the morphology pattern for Nonmass mammography reports were available, the sensitivity of type lesion between the non-high grade (I + II) and high grade (III) pure mammography was 74% (16/22). The result was comparable DCIS. to other published studies [15, 17, 19]. It was found that most false-negative diagnosis of DCIS by MRI appeared to be non-high-grade, noncomedo-type lesions [23, 32, 33]. Therefore, no significant differences were found between In this study, we had two false negative cases of high-grade enhancement kinetics of high-grade and non-high-grade DCIS with noncomedo morphology. One case showed strong DCIS (P = .38). Among the other 8 enhanced lesions background tissue enhancements in both breasts, and the that showed benign type enhancement kinetic curves or 1.4 cm lesion could not be identified. The other case showed undetermined kinetic curves, 6 lesions showed malignant clumped enhancement in the affected breast, and the 1.1 cm morphological features. Therefore, of the total 31 cases, DCIS could not be identified. Journal of Oncology 5 01 3 5 7 9 01 3 5 7 9 Time (min) Time (min) Data Data Fitted Fitted Figure 1: A 61-year-old woman with low-grade pure DCIS. Axial Figure 2: A 55-year-old woman with intermediate-grade pure precontrast T1-weighted image (top), postcontrast subtraction DCIS. Axial precontrast T1-weighted image (top), postcontrast image (middle), and maximum intensity projection (bottom) show subtraction image (middle), and maximum intensity projection an irregular mass lesion of 1.8 cm in the left breast (arrow). The (bottom) show several foci in the right breast. Enhancement enhancement level was moderate, but clearly visible. Enhancement kinetics measured from a focus lesion (arrow) demonstrates a rapid kinetics demonstrates a moderate initial enhancement reaching to a initial enhancement followed by washout. plateau. Nuclear grade has been consistently associated with poor MRI for non-high-grade pure DCIS is also significantly prognosis and local recurrence in DCIS [26, 34–36], and higher than mammography [23]. In the series reported the combination of nuclear grade and comedo necrosis by Vag et al. [31], all 12 mammographically occult DCIS was reported to correlate with the risk of local recurrence lesions (three low grade, four intermediate grade, five high after breast conserving surgery [34, 35]. Kuhl et al. found grade) were correctly diagnosed by MRI. In our series, 4 that high-grade pure DCIS missed by mammography can mammographically occult DCIS lesions were detected by be diagnosed by MRI alone [23]. The diagnostic yield of MRI. All these 4 lesions were high grade. With the prognostic Signal enhancement (%) Signal enhancement (%) 6 Journal of Oncology 01 3 5 7 9 Time (min) 0 1 357 9 Data Time (min) Fitted Data Figure 4: A 39-year-old woman with high-grade pure DCIS. Axial Fitted precontrast T1-weighted image (top), postcontrast subtraction Figure 3: A 61-year-old woman with intermediate-grade pure image (middle), and maximum intensity projection (bottom) show DCIS. Axial precontrast T1-weighted image (top), postcontrast a 2.8 cm mass lesion with spiculated margin in the left breast. subtraction image (middle), and maximum intensity projection Enhancement kinetics demonstrates a rapid initial enhancement (bottom) show a mass lesion of 2.2 cm with spiculated margin in followed by washout. the left breast. Enhancement kinetics demonstrates a rapid initial enhancement followed by washout. of focal branching enhanced pattern on MRI for DCIS. As the spatial resolution of MRI improves, it is anticipated significance of early detection for high-grade DCIS, this that the ductal pattern as linear or linear branching may result further strengthens the recommendation of MRI for be seen more often, which can be a signature feature on diagnosis of DCIS. MRI suggesting DCIS. In our study, the typical morphologic Pure DCIS lesions often appear as Nonmass clumped appearance of pure DCIS on MRI was a mass- or a Nonmass- enhancement in a regional, ductal, or linear distribution like lesion with heterogeneous or clumped enhancement. [16, 18, 21, 22]. Groves et al. [19] reported a high specificity Although our study showed a higher percentage of mass Signal enhancement (%) Signal enhancement (%) Journal of Oncology 7 if some ill-defined mass lesions are reclassified as Nonmass lesions. Similar to that of Viehweg et al. [34], we did not find significant differences between morphologic patterns of high-grade and non-high-grade DCIS. Pure DCIS does not always exhibit the typical malignant washout kinetic curves and could show persistent and plateau curve types [16, 18, 21, 22]. Jansen et al. reported that the peak enhancement ratio at one minute (E1) for pure DCIS was less than invasive cancers and more than benign lesions [22]. Studies on the enhancement kinetic characteristics among the different nuclear grades of pure DCIS did not show consistent results. Some reports have indicated that the kinetic characteristics of low-grade pure DCIS lesions are different from those of intermediate- and high-grade lesions [18, 37], whereas other studies have revealed no difference [22, 34]. We did not find significant difference between the enhancement kinetics of high-grade and non-high-grade groups. For the size measurement of DCIS, overall, MRI was more trustworthy compared with mammography. Different local recurrence rates were found between DCIS lesions smaller and larger than 10 mm, thus an accurate size measurement is important [38]. Boetes et al. [39] showed a −8% deviation of MRI measured tumor size relative to histopathologic size, compared with −29% for mammogra- phy. Despite that in general the size measurement is more accurate on MRI, false positive findings and tumor size over- estimation may occur on MRI. Kumar et al. [40]reported 80 that cases in which MRI overestimated DCIS were mostly non-high-grade and noncomedo-type lesions. The false- positive enhancement in most cases is due to coexistence of benign proliferative processes such as fibrocystic changes or atypical ductal hyperplasia [16, 40]. Several limitations existed in our study, including small case number and retrospective case review. Nevertheless, the reported cases were from consecutive patients referred to participate in a breast MRI research study, with diagnosis of pure DCIS; therefore, allowing objective analysis as presented in this study. The research study was designed to analyze the 01 3 5 7 9 DCE kinetics, so a protocol with a relatively high temporal Time (min) resolution (42 seconds compared to 2 minutes used in a clinical setting) was chosen. This could only be accomplished Data by using a compromised spatial resolution, which would Fitted inevitably affect the quality of the image. However, since the Figure 5: A 47-year-old woman with high-grade pure DCIS. Axial tumor size of our subjects was relatively large (1.6 ± 1.2cm precontrast T1-weighted image (top), postcontrast subtraction for mass lesions and 2.2 ± 1.3 cm for Nonmass lesions), image (middle), and maximum intensity projection (bottom) show we believe that the relatively low spatial resolution did not a Nonmass-like lesion with ductal clumped enhancement pattern in affect our findings on the analysis of lesion morphology. the right breast. Enhancement kinetics demonstrates a rapid initial The morphological features of the three focal lesions <5mm enhancement then reaching to a plateau. were not evaluated. The feature about spiculated margin might be affected by the low spatial resolution, and the percentage of lesions with spiculated margin could be higher lesions (52%) (Figures 3 and 4) compared to previous than the reported 42% (5/12 cases). Therefore, the cases publications [18, 22], the classification of mass and Nonmass with spiculated and irregular margin were reported together. With improved spatial resolution and reduced slice thickness, lesions is subjective, and this may lead to variations in the determined percentages. In the study by Viehweg et al. [34], it is possible that more subtle morphological features, of the 48 enhancing pure DCIS lesions, 35 lesions (35/48, such as linear or linear branching rather than regional enhancements, can be revealed for improved diagnosis of 73%) showed either well-defined (N = 12) or ill-defined focal mass lesions (N = 23). The percentage will change DCIS. Signal enhancement (%) 8 Journal of Oncology 5. Conclusion [10] H. R. MacDonald, M. J. Silverstein, L. A. 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Characterization of Pure Ductal Carcinoma In Situ on Dynamic Contrast-Enhanced MR Imaging: Do Nonhigh Grade and High Grade Show Different Imaging Features?

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Hindawi Publishing Corporation
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Copyright © 2010 Siwa Chan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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10.1155/2010/431341
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Hindawi Publishing Corporation Journal of Oncology Volume 2010, Article ID 431341, 9 pages doi:10.1155/2010/431341 Clinical Study Characterization of Pure Ductal Carcinoma In Situ on Dynamic Contrast-Enhanced MR Imaging: Do Nonhigh Grade and High Grade Show Different Imaging Features? 1 2, 3 2 2 4 Siwa Chan, Jeon-Hor Chen, Garima Agrawal, Muqing Lin, Rita S. Mehta, 5 2 2 Philip M. Carpenter, Orhan Nalcioglu, and Min-Ying Su Department of Radiology, Taichung Veterans General Hospital, Taichung 404, Taiwan Tu and Yuen Center for Functional Onco-Imaging and Department of Radiological Science, University of California, Irvine, Ca 92697, USA Department of Radiology, China Medical University Hospital, Taichung 404, Taiwan Department of Medicine, University of California, Irvine, Ca 92868, USA Department of Pathology, University of California, Irvine, Ca 92868, USA Correspondence should be addressed to Jeon-Hor Chen, jeonhc@uci.edu Received 30 April 2010; Revised 4 July 2010; Accepted 5 August 2010 Academic Editor: Aysegula A. Sahin Copyright © 2010 Siwa Chan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To characterize imaging features of pure DCIS on dynamic contrast-enhanced MR imaging (DCE-MRI), 31 consecutive patients (37-81 years old, mean 56), including 2 Grade I, 16 Grade II, and 13 Grade III, were studied. MR images were reviewed retrospectively and the morphological appearances and kinetic features of breast lesions were categorized according to the ACR BI-RADS breast MRI lexicon. DCE-MRI was a sensitive imaging modality in detecting pure DCIS. MR imaging showed enhancing lesions in 29/31 (94%) cases. Pure DCIS appeared as mass type or non-mass lesions on MRI with nearly equal frequency. The 29 MR detected lesions include 15 mass lesions (52%), and 14 lesions showing non-mass-like lesions (48%). For the mass lesions, the most frequent presentations were irregular shape (50%), irregular margin (50%) and heterogeneous enhancement (67%). For the non-mass-like lesions, the clumped internal enhancement pattern was the dominate feature, seen in 9/14 cases (64%). Regarding enhancement kinetic curve, 21/29 (78%) lesions showed suspicious malignant type kinetics. No significant difference was found in morphology (P> .05), tumor size (P = 0.21), and kinetic characteristics (P = .38) between non-high grade (I+II) and high-grade (III) pure DCIS. 1. Introduction cancer, with the trend still increasing [4]. In mammogra- phy, DCIS most frequently presents as microcalcifications, Ductal Carcinoma In Situ (DCIS) is characterized by accounting for about 85%−90% of diagnosed cases. An proliferation of malignant cells confined by the basement accurate preoperative staging is very important for treatment membranes of ductal structures, without evidence of extra- planning of DCIS. Although mammography has been the ductal invasion [1]. DCIS comprises different subtypes mainstay for diagnosis of DCIS, it has limitations in defining with heterogeneous proliferative disease processes and varies the extension and the margin, especially in patients without in architecture, imaging features, and clinical outcome. microcalcifications or in those with dense breasts or breast Although the progression of DCIS is not fully understood, implants. Furthermore, there is a tendency to underestimate it is known that untreated DCIS is likely to progress to the tumor size of DCIS on mammography [5–7]. Positive invasive cancer within 10 years of diagnosis. Therefore, DCIS surgical margin is known as an independent risk factor for is considered a preinvasive form of invasive breast cancer that localrecurrence[8–10]. requires immediate treatment [2, 3]. Dynamic contrast-enhanced MRI (DCE-MRI) has been With the widespread use of screening mammography, proven more sensitive than mammography for detecting DCIS now accounts for 15%−20% of all newly detected breast breast cancer in young women with a high risk of developing 2 Journal of Oncology breast cancer [11–13]. In many instances, DCE-MRI can precontrast imaging and dynamic contrast-enhanced imag- reveal early stage breast cancer, including DCIS and DCIS ing. After setting the IV line, the patient was placed into with small invasive carcinomas, which are mammographi- the scanner in the prone position. The breasts were gently cally, sonographically, and clinically occult. In addition to cushioned inside the coil to reduce motion. The localizer screening, breast MR can also be used for staging purposes scan was first taken to define the location of breasts. Then a to better characterize the disease extent and the presence sagittal view unilateral T1-weighted precontrast images were of multifocal multicentric lesions, which can impact on acquired from the breast of concern, using a spin echo pulse treatment planning and the subsequent management. sequence with TR = 1000 ms, TE = 12 ms, and FOV = 20 cm, Imaging characterization of patients with mixed cohort and matrix size = 256 × 256. Following this, a 3D SPGR of pure DCIS and DCIS with invasive components [14– (RF-FAST) pulse sequence with 16 frames (repetitions) 17] and patients with merely pure DCIS [18–25]onDCE- was prescribed for bilateral dynamic imaging. Thirty-two MRI has been reported before. In a study of 167 patients, axial slices with 4 mm thickness were used to cover both Kuhl et al. found that mammography only diagnosed 56% breasts. The imaging parameters were TR = 8.1 ms, TE = pure DCIS preoperatively, while MRI achieved a diagnostic 4.0 ms, flip angle = 20 ,matrixsize = 256 × 128, FOV = rate of 92%. For 89 high-grade lesions, MRI detected 87 32−38 cm. The scan time was 42 sec per acquisition. The lesions (98%) while mammography only diagnosed 52% of sequence was repeated 16 times for dynamic acquisitions, lesions [23]. Nevertheless, consensus regarding how MRI four precontrast, and 12 postcontrast sets. The contrast agent can be used to aid in management of pure DCIS has not (Omniscan, 1 cc/10 lbs body weight) was manually injected been reached yet. Given the recent evidence that additional at the beginning of the 5th acquisition and was timed to diseases diagnosed by preoperative MRI often led to more finish in 12 seconds to make the bolus length consistent for aggressive treatment yet did not improve the treatment all patients. Immediately following the contrast, 10 cc saline outcome [26, 27], continuing exploration of the role of breast was injected to flush in all contrast medium. MRI for the diagnosis of DCIS is needed. The purpose of this retrospective study was to character- 2.3. Enhancement Kinetic Time Course. All images were ize the morphology and enhancement kinetic pattern of pure transferred to a PC for analysis. The subtraction images at DCIS on DCE-MRI. Since high-grade DCIS is associated 1-minute postinjection were generated by subtracting the with a greater risk of local recurrence and progression to precontrast images acquired in Frame number 3 from the invasive breast cancer [28–30], it would be very helpful if the postcontrast-enhanced images acquired in Frame number 6. high-grade and low-grade DCIS could be differentiated on The maximum intensity projections (MIPs) were also gener- imaging. In this paper, the MRI features of DCIS between ated from the subtraction images to help identify the lesion. high-grade (Grade III) and non-high-grade (including low The enhancement kinetic was analyzed from manually Grade I and intermediate Grade II) DCIS based on the van selected ROI (Region of Interest) based on the subtraction Nuys classification [31] were compared. images at 1-minute post-injection. The enhanced tumor area was outlined on each imaging slice covering the lesion by an experienced breast radiologist; then a mean signal intensity 2. Materials and Methods time course from all 16 time frames was obtained. The 2.1. Patients. A total of 34 consecutive patients with percentenhancement time course wascalculatedbyfirstsub- histological-proven pure DCIS (without any microinvasion) tracting the mean precontrast signal intensity (mean of first were identified from our breast MRI database collected 4 frames) from each of the subsequent 12 postcontrast signal from 2002 to 2006. These patients came to our center to intensities and then normalized by the mean precontrast participate in a breast MRI research study due to suspicious signal intensity ×100%. lesions found in mammography, sonography, or physical examination. The medical records, breast MRI images, and 2.4. MR Imaging Feature Analysis. Morphological appear- mammogram reports (if available) were reviewed retrospec- ances and enhancement kinetic features of lesions shown on tively. Among these 34 patients, three patients had received MRI were categorized according to the ACR Breast Imaging surgical excision biopsy before MR imaging, and they were Reporting and Data System (BI-RADS) breast MRI lexicon excluded in the analysis. The remaining 31 patients were [30]. The features were evaluated by 2 radiologists (with 4 37−81 years old (mean 56). The final diagnosis of pure DCIS and 5 years of experience in reading breast MRI) separately. was obtained from pathological examination of mastectomy For cases with different results, they were discussed to (N = 21) and lumpectomy (N = 10) specimens. Screening reach a consensus. Based on the enhancement of lesions, mammography reports were available for 22 patients. This the morphology was first separated into mass lesions and study was approved by the institutional review board, and Nonmass-like lesions. Based on the lesion size, the mass informed consents were obtained from all patients. type can be further separated into single focus/multiple foci (<5 mm) and mass (≥5 mm). Then for mass lesions 2.2. MR Imaging Protocol. The MRI study was performed other characteristics such as shape, margin, and internal using a 1.5 T Phillips Eclipse MR scanner with a standard enhancement patterns were evaluated. The Nonmass-like bilateral breast coil (Philips Medical Systems, Cleveland, lesions were described by the type of enhancements (diffuse, Ohio). The imaging protocol consisted of high-resolution regional, segmental, focal, ductal, linear) and the internal Journal of Oncology 3 enhancement patterns (punctate/stippled, clumped, and Table 1: Pathological types and grades of 31 pure DCIS lesions. heterogeneous). The tumor size was measured as the longest Grade I Grade II Grade III Total diameter on the maximum intensity projection (MIP) of Noncomedo type 2 11 6 19 subtraction image. Comedo type 0 5 7 12 The enhancement kinetics was divided into two phases: the initial enhancement phase, defined as enhancement Total 2 16 13 31 patterns within the first 2 minutes or before the curve starts to change, and the delayed phase, defined as enhancement pattern after 2 minutes or after the curve starts to change. non-high grade DCIS and 2.2± 1.3 cm for high-grade DCIS, The initial enhancement phase was classified as fast, medium, not significantly different (P = .21). and slow. The delayed enhancement phase was described For the two false negative cases, in mammography, one as persistent, plateau, and washout pattern. When the case was occult, and the other was undetermined (i.e., needed enhancement kinetics showed a rapid initial enhancement additional imaging evaluation). The mammographically followed by washout or reaching to a plateau in the delayed occult case received ultrasound exam and found a suspicious phase, it was determined as suspicious of malignancy. hypoechoic mass in the left breast. After needle biopsy con- firming malignancy, the patient received lumpectomy, and a pure DCIS of 1.4 cm was found. The mammographically 2.5. Histopathology. All cases are pure DCIS without pres- undetermined case had a palpable nodule in her left breast. ence of microinvasion. The pathological diagnosis was This patient was diagnosed with DCIS in the right breast 2 evaluated based on the van Nuys system [29]. DCIS was years ago and had already received right mastectomy. She classified according to the nuclear grade (non-high grade decided to receive left mastectomy, and a pure high grade versus high grade) and the morphologic subtype (comedo DCIS of 1.1 cm was found. and noncomedo). Grade-I (low grade) and Grade-II (inter- mediate grade) were categorized as non-high grade, and grade-III was the high-grade. 3.2.2. Mass Lesions. Among the 15 mass lesions, 9 cases were non-high grade, and 6 were high grade. For the 14 Nonmass- like lesions, 9 lesions were non-high grade, and 5 cases were 2.6. Statistical Analysis. For statistical analysis, Fisher’s exact high grade (P = .26). The shape, margin, and internal test was used to examine the significant difference between enhancement patterns were evaluated in 12 mass lesions non-high grade DCIS and high grade DCIS. A P-value < .05 that were ≥5 mm. The most frequently seen features were was considered statistically significant. irregular shape (50%), spiculated/irregular margin (92%), and heterogeneous enhancement (67%) (Table 3). There was 3. Results no significant difference in the MR morphology pattern between the non-high-grade and high-grade mass type DCIS 3.1. Patient and Tumor Characteristics. According to the lesions. Three case examples are shown in Figure 1 (low nuclear grading system, 2 patients had Grade-I, 16 patients grade), Figure 3 (intermediate grade), and Figure 4 (high had Grade-II, and 13 patients had Grade-III, all together grade). 18 non-high grade and 13 high grade. The mean age for non-high grade DCIS was 52 years old and 57 years old for 3.2.3. Nonmass-Like Lesions. Of 14 Nonmass lesions, 4 high-grade DCIS (P = .27). The comedo type was noted lesions showed regional enhancement (28%), 3 showed duc- in 12 patients (7 high grade and 5 non-high grade), and tal (22%), and 3 showed focal (22%) enhancements. Figure 2 the noncomedo type was noted in 19 patients (6 high grade shows one case example with multiple foci (intermediate and 13 non-high grade) (Table 1). There was no significant grade). Internal enhancement pattern was dominated by the difference in the histological comedo or noncomedo subtype clumped pattern (Figure 5, high grade) (9/14, 64%) followed between the non-high grade and high grade DCIS (P> .05). by the heterogeneous enhancement pattern (4/14, 29%) (Table 4). 3.2. MR Morphology Analysis 3.2.1. Tumor Size and Mass versus Nonmass Morphology. 3.3. MR Enhancement Kinetic Curve Assessment. The MR imaging showed contrast-enhanced lesions in 29/31 enhancement kinetic curves were measured from 27 lesions. (94%) cases. Two cases of high-grade DCIS with noncomedo Two Grade-II lesions had severe motion artifacts due to morphology were not detected by MRI and were false patient’s movement during the delayed phase, and the negative diagnosis. The imaging features of these 29 cases are enhancement kinetic curves could not be reliably measured. summarized in Table 2, and 5 case examples are shown in The early postcontrast subtraction images had good quality, Figures 1−5. Among these 29 cases, mass lesions were seen in and the morphological features of these two lesions could 15 cases (52%) including 12 masses and 3 focus/foci lesions be evaluated. Twenty-one lesions (21/27, 78%) showed and Nonmass-like lesions in 14 cases (48%). Two cases were the suspicious malignant type enhancement kinetics with multifoci (Figures 2 and 5), and the size was not measured. a rapid initial enhancement followed by plateau (Figures For the remaining cases, the size ranged from 0.4 to 5 cm with 1 and 5) or washout (Figures 2−4), including 1/2 Grade-I the mean of 1.9± 1.2cm. The mean size was 1.6± 1.2cm for lesion, 12/14 Grade-II lesions, and 8/11 Grade-III lesions. 4 Journal of Oncology Table 2: MR imaging features of 29 pure DCIS lesions detected by MRI. Grade I Grade II Grade III Total % Morphology (N = 29) Focus/Foci (N = 3) 0 3 0 3/29 (11%) Mass (N = 12) 1 5 6 12/29 (41%) Nonmass (N = 14) 1 8 5 14/29 (48%) Enhancement kinetics (N = 27) Fast washout (N = 16) 1 8 7 16/27 (59%) Fast plateau (N = 5) 0 4 1 5/27 (19%) Continuous enhancement (N = 6) 1 2 3 6/27 (22%) Table 3: Morphological characteristics of 12 mass lesions. MRI diagnosed 27 as suspicious of malignancy, with the sensitivity of 87% (27/31). Grade I Grade II Grade III Total Margin 3.4. Correlation of MRI and Mammography Findings. Cor- Spiculated 0 4 1 5 (42%) relation between screening mammogram and MR Imaging Irregular 1 1 4 6 (50%) was performed in 22 patients whose mammography reports Smooth 0 0 1 1 (8%) were available. Sixteen lesions (16/22, 73%) were classified Shape as BI-RADS 4 or 5, as “suspicious” or “highly suspicious Irregular 1 2 3 6 (50%) of malignancy” on mammography. Five of 22 patients were Lobular 0 2 1 3 (25%) classified as BI-RADS category 1 (normal mammogram) and one patient as BI-RADS category-0 (need additional Round/Ovoid 0 1 2 3 (25%) imaging evaluation). On MRI, four of 5 patients with normal Internal Enhancement mammogram were correctly diagnosed as suspicious of Rim 0 0 1 1 (8%) malignancy, showing malignant type enhancement kinetics Homogenous 0 1 2 3 (25%) (rapid enhancement followed by washout or plateau) and/or Heterogeneous 1 4 3 8 (67%) the morphological appearance (irregular shape and spicu- There was no significant difference of the morphology pattern for mass type lated/irregular margin). lesion between the non-high-grade (I + II) and high-grade (III) pure DCIS. 4. Discussion Table 4: Morphological characteristics of 14 Nonmass lesions. Mammography may miss DCIS that does not present certain Grade I Grade II Grade III Total suspicious patterns of microcalcifications, and MRI may have Enhancement Type a complementary role in diagnosis of these lesions. Most Diffuse 0 0 1 1 (7%) of the MR imaging studies of DCIS analyzed mixed patient Regional 1 2 1 4 (28%) cohort of pure DCIS and DCIS with invasive components. Several studies reported the MR kinetic and morphologic Segmental 0 1 1 2 (14%) appearance of pure DCIS correlated with histopathology Focal 0 3 0 3 (22%) findings [18–25]. In a study by Kuhl et al., only 56% pure Ductal 0 1 2 3 (22%) DCIS was detected by mammography, while MRI could Linear 0 1 0 1 (7%) detect more than 90% [23]. In another study of 33 pure DCIS Enhancement Pattern patients by Vag et al. [24] the sensitivity of mammography Punctate/stippled 0 0 1 1 (7%) and MRI was 64% and 88%, respectively. In this study, we Clumped 1 5 3 9 (64%) detected 29/31 (94%) enhancing lesions and diagnosed 27/31 Heterogeneous 0 3 1 4 (29%) (87%) as suspicious of malignancy. Of the 22 patients whose There was no significant difference of the morphology pattern for Nonmass mammography reports were available, the sensitivity of type lesion between the non-high grade (I + II) and high grade (III) pure mammography was 74% (16/22). The result was comparable DCIS. to other published studies [15, 17, 19]. It was found that most false-negative diagnosis of DCIS by MRI appeared to be non-high-grade, noncomedo-type lesions [23, 32, 33]. Therefore, no significant differences were found between In this study, we had two false negative cases of high-grade enhancement kinetics of high-grade and non-high-grade DCIS with noncomedo morphology. One case showed strong DCIS (P = .38). Among the other 8 enhanced lesions background tissue enhancements in both breasts, and the that showed benign type enhancement kinetic curves or 1.4 cm lesion could not be identified. The other case showed undetermined kinetic curves, 6 lesions showed malignant clumped enhancement in the affected breast, and the 1.1 cm morphological features. Therefore, of the total 31 cases, DCIS could not be identified. Journal of Oncology 5 01 3 5 7 9 01 3 5 7 9 Time (min) Time (min) Data Data Fitted Fitted Figure 1: A 61-year-old woman with low-grade pure DCIS. Axial Figure 2: A 55-year-old woman with intermediate-grade pure precontrast T1-weighted image (top), postcontrast subtraction DCIS. Axial precontrast T1-weighted image (top), postcontrast image (middle), and maximum intensity projection (bottom) show subtraction image (middle), and maximum intensity projection an irregular mass lesion of 1.8 cm in the left breast (arrow). The (bottom) show several foci in the right breast. Enhancement enhancement level was moderate, but clearly visible. Enhancement kinetics measured from a focus lesion (arrow) demonstrates a rapid kinetics demonstrates a moderate initial enhancement reaching to a initial enhancement followed by washout. plateau. Nuclear grade has been consistently associated with poor MRI for non-high-grade pure DCIS is also significantly prognosis and local recurrence in DCIS [26, 34–36], and higher than mammography [23]. In the series reported the combination of nuclear grade and comedo necrosis by Vag et al. [31], all 12 mammographically occult DCIS was reported to correlate with the risk of local recurrence lesions (three low grade, four intermediate grade, five high after breast conserving surgery [34, 35]. Kuhl et al. found grade) were correctly diagnosed by MRI. In our series, 4 that high-grade pure DCIS missed by mammography can mammographically occult DCIS lesions were detected by be diagnosed by MRI alone [23]. The diagnostic yield of MRI. All these 4 lesions were high grade. With the prognostic Signal enhancement (%) Signal enhancement (%) 6 Journal of Oncology 01 3 5 7 9 Time (min) 0 1 357 9 Data Time (min) Fitted Data Figure 4: A 39-year-old woman with high-grade pure DCIS. Axial Fitted precontrast T1-weighted image (top), postcontrast subtraction Figure 3: A 61-year-old woman with intermediate-grade pure image (middle), and maximum intensity projection (bottom) show DCIS. Axial precontrast T1-weighted image (top), postcontrast a 2.8 cm mass lesion with spiculated margin in the left breast. subtraction image (middle), and maximum intensity projection Enhancement kinetics demonstrates a rapid initial enhancement (bottom) show a mass lesion of 2.2 cm with spiculated margin in followed by washout. the left breast. Enhancement kinetics demonstrates a rapid initial enhancement followed by washout. of focal branching enhanced pattern on MRI for DCIS. As the spatial resolution of MRI improves, it is anticipated significance of early detection for high-grade DCIS, this that the ductal pattern as linear or linear branching may result further strengthens the recommendation of MRI for be seen more often, which can be a signature feature on diagnosis of DCIS. MRI suggesting DCIS. In our study, the typical morphologic Pure DCIS lesions often appear as Nonmass clumped appearance of pure DCIS on MRI was a mass- or a Nonmass- enhancement in a regional, ductal, or linear distribution like lesion with heterogeneous or clumped enhancement. [16, 18, 21, 22]. Groves et al. [19] reported a high specificity Although our study showed a higher percentage of mass Signal enhancement (%) Signal enhancement (%) Journal of Oncology 7 if some ill-defined mass lesions are reclassified as Nonmass lesions. Similar to that of Viehweg et al. [34], we did not find significant differences between morphologic patterns of high-grade and non-high-grade DCIS. Pure DCIS does not always exhibit the typical malignant washout kinetic curves and could show persistent and plateau curve types [16, 18, 21, 22]. Jansen et al. reported that the peak enhancement ratio at one minute (E1) for pure DCIS was less than invasive cancers and more than benign lesions [22]. Studies on the enhancement kinetic characteristics among the different nuclear grades of pure DCIS did not show consistent results. Some reports have indicated that the kinetic characteristics of low-grade pure DCIS lesions are different from those of intermediate- and high-grade lesions [18, 37], whereas other studies have revealed no difference [22, 34]. We did not find significant difference between the enhancement kinetics of high-grade and non-high-grade groups. For the size measurement of DCIS, overall, MRI was more trustworthy compared with mammography. Different local recurrence rates were found between DCIS lesions smaller and larger than 10 mm, thus an accurate size measurement is important [38]. Boetes et al. [39] showed a −8% deviation of MRI measured tumor size relative to histopathologic size, compared with −29% for mammogra- phy. Despite that in general the size measurement is more accurate on MRI, false positive findings and tumor size over- estimation may occur on MRI. Kumar et al. [40]reported 80 that cases in which MRI overestimated DCIS were mostly non-high-grade and noncomedo-type lesions. The false- positive enhancement in most cases is due to coexistence of benign proliferative processes such as fibrocystic changes or atypical ductal hyperplasia [16, 40]. Several limitations existed in our study, including small case number and retrospective case review. Nevertheless, the reported cases were from consecutive patients referred to participate in a breast MRI research study, with diagnosis of pure DCIS; therefore, allowing objective analysis as presented in this study. The research study was designed to analyze the 01 3 5 7 9 DCE kinetics, so a protocol with a relatively high temporal Time (min) resolution (42 seconds compared to 2 minutes used in a clinical setting) was chosen. This could only be accomplished Data by using a compromised spatial resolution, which would Fitted inevitably affect the quality of the image. However, since the Figure 5: A 47-year-old woman with high-grade pure DCIS. Axial tumor size of our subjects was relatively large (1.6 ± 1.2cm precontrast T1-weighted image (top), postcontrast subtraction for mass lesions and 2.2 ± 1.3 cm for Nonmass lesions), image (middle), and maximum intensity projection (bottom) show we believe that the relatively low spatial resolution did not a Nonmass-like lesion with ductal clumped enhancement pattern in affect our findings on the analysis of lesion morphology. the right breast. Enhancement kinetics demonstrates a rapid initial The morphological features of the three focal lesions <5mm enhancement then reaching to a plateau. were not evaluated. The feature about spiculated margin might be affected by the low spatial resolution, and the percentage of lesions with spiculated margin could be higher lesions (52%) (Figures 3 and 4) compared to previous than the reported 42% (5/12 cases). Therefore, the cases publications [18, 22], the classification of mass and Nonmass with spiculated and irregular margin were reported together. With improved spatial resolution and reduced slice thickness, lesions is subjective, and this may lead to variations in the determined percentages. In the study by Viehweg et al. [34], it is possible that more subtle morphological features, of the 48 enhancing pure DCIS lesions, 35 lesions (35/48, such as linear or linear branching rather than regional enhancements, can be revealed for improved diagnosis of 73%) showed either well-defined (N = 12) or ill-defined focal mass lesions (N = 23). The percentage will change DCIS. Signal enhancement (%) 8 Journal of Oncology 5. Conclusion [10] H. R. MacDonald, M. J. Silverstein, L. A. 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