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Objectives The purpose of this study was to evaluate lesion detectability of a dedicated breast positron-emission tomography (dbPET) scanner for breast cancers with an updated reconstruction mode, comparing it to whole-body positron-emission tomography/computed tomography (WB-PET/CT). Materials and methods A total of 179 histologically-proven breast cancer lesions in 150 females who underwent both WB-PET/CT and dbPET with 18 F-fluorodeoxyglucose were retrospectively analyzed. The patient/breast/lesion-based sensitivities based on visual analysis were compared between dbPET and WB-PET/CT. For lesions visible on both PET images, SUVmax values of the tumors were measured, and tumor-to-background ratios (T/B ratios) of SUVmax were compared between the two scans. Subgroup analyses according to clinical tumor stage, histopathology and histological grade were also performed. Results Patient/breast/lesion-based sensitivities were 95%, 95%, and 92%, respectively, for dbPET, and 95%, 94%, and 88%, respectively, for WB-PET/CT. Mean±standard deviation SUVmax values of FDG-avid tumors were 13.0±9.7 on dbPET and 6.4±4.8 on WB-PET. T/B ratios were also significantly higher in dbPET than in WB-PET/CT (8.1±7.1 vs. 5.1±4.5). In the subgroup analysis, no significant differences in sensitivities between dbPET and WB-PET/CT were found. However, T/B ratios of dbPET were significantly higher than those of WB-PET/CT in cT1c, cT2, cT3, invasive cancer, invasive carcinoma of no special type, mucinous carcinoma and Grades 1–3. Conclusion No significant differences in sensitivities were identified between dbPET using an updated reconstruction mode and WB-PET/CT; however, T/B ratios of dbPET were significantly higher than those of WB-PET/CT, indicating higher tumor conspicuity on dbPET.

To compare the diagnostic performance of the kinetic parameter maximum slope (MS) in breast lesions obtained by ultrafast dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) of the contrast wash-in period with that of the washout index (WI) derived from standard DCE MRI and that of the Breast Imaging Reporting and Data System (BI-RADS) category.In total, 138 contrast enhanced lesions (90 malignant, 48 benign) were evaluated. Ultrafast DCE MRI images were acquired using a k-space-weighted image contrast (KWIC), obtained 0-1 min after gadolinium injection (3.75 s/frame; 16 frames) and followed by standard DCE MRI (60 s/frame, 3 frames). MS was calculated for the KWIC time series as percentage relative enhancement per second (%/s). As a semi-quantitative parameter for the standard DCE MRI time series, WI was evaluated using the change in signal intensity between early and delayed phases. The diagnostic performance (malignant/benign differentiation) of MS, WI, and BI-RADS category was compared by ROC analysis using the area under the curve (AUC).The AUC of MS was as good as that of WI (0.81 vs. 0.79, respectively; P = 0.81), yet inferior to the BI-RADS category (0.81 vs. 0.96, respectively;0.001). MS tended to have higher sensitivity (91.1% [82/90]) compared with WI (87.8% [79/90]) with same specificity (62.5% [30/48]).MS obtained by ultrafast DCE MRI of the breast is a promising kinetic parameter in the differential diagnosis of malignant and benign breast lesions with decreased scanning time.

Purpose To evaluate the influence of heart rate (HR) on magnetic resonance coronary angiography (MRCA) image quality in diastolic and systolic phases. Materials and methods Twenty-seven healthy volunteers (9 men; 33 ± 9 years, HR 53–110 bpm), were evaluated with the electrocardiography and three-dimensional navigator-gating MRCA in a 1.5-T MR scanner (Avanto, Siemens) in diastolic and systolic phases (steady-state free precession; TR/TE/flip angle = 3.2 ms/1.6 ms/90°). The timing of scanning was individually adapted to the cardiac rest periods obtained in the prescanning, by visually identifying when the movement of right coronary artery was minimized during diastole and systole. Images of two phases were side-by-side compared on a four-point scale (from 1 = poor to 4 = excellent visibility; score of 3 or 4 as diagnostic). Results Of 13 subjects with HR ≤65 bpm (low HR group, mean 59.8 ± 4.9 bpm, range 53–65), the image quality scores were significantly better than that with higher heart rates (73.9 ± 9.0 bpm, range 68–110) in diastolic MRCA. The image quality was significantly improved during systole in high HR group. Overall, 91.3% of low HR group had MRCA image of diagnostic quality acquired at diastole, while 88.3% of high HR group had diagnostic images at systole by segmental analysis (p = NS). Conclusions MRCA at systole offered superior quality in patients with high heart rates.

To evaluate inter-observer agreement and the predictive value of tumor size measurements using MRI for breast cancer under neoadjuvant chemotherapy (NAC) by comparing the measurements of the longest diameters (LD), total enhanced volumes (TEV) and washout volumes (WOV).Thirty-seven female breast cancer patients were prospectively enrolled from August 2008 to October 2010. Two of these patients had locally advanced disease. MRI examinations were acquired within 2 weeks before and after NAC. Interim scans were also conducted in 30 patients. Tumor resection was undertaken within 2 weeks after the cessation of NAC. MRI images were independently measured for LD, TEV and WOV by two experienced radiologists. Inter-observer agreement was evaluated using concordance correlation coefficients (CCCs). Tumor sizes after NAC were evaluated relative to their initial sizes for early prediction of a pathological complete response (pCR).The CCCs were 0.93 (CI: 0.90-0.95) for LD, 0.98 (CI: 0.97-0.98) for TEV and 0.99 (CI: 0.991-0.996) for WOV. All measurements had high inter-observer agreement, but the CCCs were significantly increased in the aforementioned order (P0.0001). WOV measured after the completion of chemotherapy had significant discriminating ability (P=0.0056) when evaluated using receiver operating characteristic analysis, and was found to be superior to LD (P=0.045). The average WOV size was significantly smaller in pCR cases than in non-pCR cases (P=0.016).Computer-aided detection-generated tumor volumes had significantly higher inter-observer concordance than conventional LD measurements. WOV measurements had the highest concordance, and WOV could better predict pCR after NAC at smaller tumor sizes.

To evaluate visualization of the whole-heart coronary arteries accelerated with parallel imaging (PI) applied in two-dimension (2D) in comparison with one-dimension (1D).Seventeen healthy subjects were studied with a 1.5-T scanner equipped with a whole body phased array coil system and 16-channel receivers. Using 16 coil elements, whole-heart coronary magnetic resonance angiography (CMRA) was acquired in two conditions of 1D-PI and 2D-PI. The former scan was accelerated in phase direction by factor of 2 and the latter in phase and slice directions by factors of 2.5 and 2, respectively. Visualized length of right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) was measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was also measured. The CMRA quality was assessed in segment-wise with a five-point scale.The average scan time decreased to 5.3+/-2.2 min in 2D-PI from 11.6+/-3.5 min in 1D-PI, reducing the scan time to 45%. The visualized length, SNR, and CNR in average were smaller for images of 2D-PI compared with those of 1D-PI, however, statistically significant results were observed only in RCA (P0.05). Score reduction of 2D-PI image quality was limited to 0.34 in average, and only two out of fifteen segments (#2, 6) showed significant score deterioration (P0.05).Compared with the relatively limited degree of image degradation, 2D-PI offered a large reduction of the acquisition time, which is of large benefit in clinical situations.