Mitsuhiro Tozaki

1H MR spectroscopy and diffusion-weighted imaging of the breast: are they useful tools for characterizing breast lesions before biopsy?

OBJECTIVE The objective of our study was to determine whether proton ((1)H) MR spectroscopy (MRS) and diffusion-weighted imaging might be useful tools for characterizing breast lesions before biopsy. MATERIALS AND METHODS Single-voxel (1)H MRS and diffusion-weighted imaging were performed in 171 suspicious or highly suspicious lesions. Using the residual water signal as a reference (4.7 ppm), a choline peak at 3.22-3.23 ppm was defined as malignant. If a high-signal-intensity lesion was detected in high-b-value (b = 1,500 s/mm(2)) images, that lesion was defined as positive for malignancy. Among the patients with positive results on diffusion-weighted imaging, the apparent diffusion coefficient (ADC) values of the mass or focus were calculated from two different gradient factors (b(1) = 500 s/mm(2) and b(2) = 1,500 s/mm(2)). RESULTS The diagnostic sensitivity and specificity of (1)H MRS were 44% (40/91) and 85% (68/80), respectively (p < 0.001). If (1)H MRS was applied for mass lesions larger than 15 mm, the diagnostic sensitivity and specificity were 82% (28/34) and 69% (11/16), respectively. Of the high-b-value images, 24 benign lesions and eight nonmass ductal carcinoma in situ were visually negative. With the use of a cutoff ADC value of 1.13 x 10(-3) mm(2)/s, a specificity of 67% (43/64) and sensitivity of 97% (61/63) was obtained on diffusion-weighted imaging. CONCLUSION (1)H MRS was useful for characterizing breast lesions measuring 15 mm or larger, and diffusion-weighted imaging was useful for characterizing lesions of any size. However, these two techniques still have potential pitfalls in relation to the diagnosis of nonmass breast lesions.

Preliminary study of ultrasonographic tissue quantification of the breast using the acoustic radiation force impulse (ARFI) technology

PURPOSE To investigate the shear wave velocity of normal breast tissue and breast lesion using acoustic radiation force impulse (ARFI) technology. MATERIALS AND METHODS This retrospective study was conducted with the approval of the institutional review board. Shear wave velocity was measured using a linear array transducer with a bandwidth of 4-9 MHz and Virtual Touch tissue quantification (Siemens Medical Solutions, Mountain View, CA, USA) in 50 patients. First, the values of the shear wave velocity were determined in the normal tissues. Then, the changes in the shear wave velocity while applying external compression on the breast were determined. For the differential diagnosis of breast lesions, the shear wave velocities of 30 mass lesions (13 benign and 17 malignant lesions) classified as BI-RADS category 4 were measured. RESULTS The mean shear wave velocities in the subcutaneous fat and the mammary gland parenchyma were 2.66 m/s and 3.03 m/s, respectively (p=0.0006). The mean shear wave velocity measured while applying external compression was 3.33 m/s for subcutaneous fat (p<0.0001), and 3.84 m/s for the mammary gland parenchyma (p<0.0001). In 4 of malignant cases, the shear wave velocity was not indicated (displayed as X.XX; unmeasurable state). The mean shear wave velocity of the 13 malignant lesions (4.49 m/s) was higher than that of benign lesions (2.68 m/s) (p<0.01). CONCLUSIONS ARFI tissue quantification is thought to be a potentially promising ultrasound technique for the diagnosis of breast lesions, but further investigation is required to identify the most appropriate method of measurement.

High-Spatial-Resolution MRI of Non-Masslike Breast Lesions: Interpretation Model Based on BI-RADS MRI Descriptors

OBJECTIVE The purpose of this study was to assess an interpretation model based on BI-RADS MRI descriptors and high-spatial-resolution MR images in lesions showing non-masslike enhancement. MATERIALS AND METHODS Retrospective review was performed of 30 consecutive lesions showing non-masslike enhancement. MRI was performed on a 1.5-T scanner using the volumetric interpolated breath-hold examination sequence. The distribution patterns were classified into three categories: single quadrant/solitary lesion (linear), single quadrant/grouped lesion (focal, regional, segmental), and multiquadrant lesion (multiple regions, diffuse). The presence of a ductal pattern was assessed in the enhancing lesions after the tumor distribution had been decided. In addition to the BI-RADS MRI descriptors, the presence of clustered ring enhancement was also assessed in heterogeneous enhancing lesions. RESULTS The most frequent morphologic finding among the benign lesions was a linear pattern (50%) followed by homogeneous internal enhancement (42%), whereas a segmental pattern (56%) (p = 0.003), heterogeneous internal enhancement (44%), and clustered ring enhancement (44%) (p = 0.01) were the most frequent findings in malignant lesions. The features with the highest positive predictive value for carcinoma were a segmental distribution (100%), a clustered ring enhancement (100%), and a clumped internal architecture (88%). Using this interpretation model, the positive predictive value for carcinoma was 94%. CONCLUSION A combination of BI-RADS MRI descriptors and clustered ring enhancement criteria is useful for the differential diagnosis of lesions showing non-masslike enhancement.

Pattern classification of ShearWaveTM Elastography images for differential diagnosis between benign and malignant solid breast masses

Background ShearWaveTM Elastography (SWE) provides a quantitative measurement of tissue stiffness and may improve characterization of breast masses. However, the significance of Youngs modulus measurements and appropriate SWE evaluation criteria has not been established yet. Purpose To assess the usefulness of the pattern classification and Youngs modulus measurements in the differential diagnosis between benign and malignant solid breast masses. Material and Methods Ninety-six patients (age range 18–84 years, mean 54 years) with 100 solid breast masses who underwent tissue sampling after a US examination were analyzed. We tried to create a visual pattern classification based on the SWE images. After classifying the visual patterns, the Youngs modulus of the lesions was measured in every case. Results It was possible to classify the images into four patterns by the visual evaluation: no findings (coded blue homogeneously; Pattern 1), vertical stripe pattern artifacts (Pattern 2), a localized colored area at the margin of the lesion (Pattern 3), and heterogeneously colored areas in the interior of the lesion (Pattern 4). There were 17 Pattern 1 lesions, 14 Pattern 2 lesions, 20 Pattern 3 lesions, and 49 Pattern 4 lesions. When Patterns 1 and 2 were assumed to be benign, and Patterns 3 and 4 were assumed to be malignant, the sensitivity and specificity were 91.3% (63/69) and 80.6% (25/31), respectively. The mean Youngs modulus measurements of the benign and the malignant lesions were 42 kPa and 146 kPa, respectively (P < 0.0001). No significant differences were found between benign and malignant lesions in Pattern 3. In Pattern 4, however, the Youngs modulus of the benign lesions (50 kPa) was lower than the smallest Youngs modulus of malignant lesions (61 kPa). Conclusion The visual pattern classification and adding Youngs modulus measurements may improve characterization of solid breast masses.

Breast MRI Using the VIBE Sequence: Clustered Ring Enhancement in the Differential Diagnosis of Lesions Showing Non-Masslike Enhancement

OBJECTIVE The purpose of this study was to assess the frequency of a finding in which minute ring enhancements are clustered (defined as clustered ring enhancement) in lesions showing non-masslike enhancement and to evaluate the clinical usefulness of this sign, in addition to that of the BI-RADS MRI descriptors, in the differentiation between benign and malignant lesions. MATERIALS AND METHODS Retrospective review was performed of 61 consecutive lesions showing non-masslike enhancement. MRI was performed on a 1.5-T system using the volumetric interpolated breath-hold examination (VIBE) sequence. The kinetic parameter was visually assessed as follows: washout, plateau, and persistent. RESULTS The most frequent morphologic finding among the malignant lesions was heterogeneous internal enhancement (69%) (p = 0.003), followed in frequency by segmental distribution (54%) (p < 0.001); whereas, stippled internal enhancement was the most frequent finding in benign lesions (50%) (p < 0.001). The presence of clustered ring enhancement was found in 63% of the malignant lesions and only 4% of the benign lesions (p < 0.001). The features with the highest positive predictive value for malignancy were a segmental distribution (100%), clustered ring enhancement (96%), and a washout pattern (94%). The specificity of clustered ring enhancement was 96% (25/26). In cases showing focal and regional enhancement, the combination of clumped internal architecture and clustered ring enhancement showed a statistically significant association with malignant lesions (p < 0.001). CONCLUSION Clustered ring enhancement is thought to be a useful sign to differentiate between benign and malignant lesions, in addition to the BI-RADS MRI descriptors.

Predicting pathological response to neoadjuvant chemotherapy in breast cancer with quantitative 1H MR spectroscopy using the external standard method.

To assess the efficacy of quantitative 1H MR spectroscopy (MRS) using the external standard method to predict the pathological response to neoadjuvant chemotherapy with an anthracycline‐based regimen in breast cancer patients.

Optimal scanning technique to cover the whole breast using an automated breast volume scanner

PurposeThe aim of this study was to assess the scanning technique for covering the whole breast using a commercially available automated breast ultrasonography (US) system.Materials and methodsA total of 40 patients in the supine position underwent automated breast US (ABVS: Siemens Medical Solutions, Mountain View, CA, USA) and hand-held US. The scanning included sequential scans in the upper-outer, lower-outer, lower-inner, and upper-inner regions. After scanning all four segments of each breast using ABVS, hand-held US was performed in all the patients. The detectability of the lesions using the ABVS technique compared with that using the handheld US was evaluated. The average scanning time was compared between any two of the three examiners with various lengths of experience in breast US.ResultsIn all, 61 lesions were detected by hand-held US. The average size of the lesions was 7.7 mm (range 2.5–26.0 mm). The number of detected lesions by ABVS was consistent with those found by hand-held US in each patient. The average total scanning time for each examiner using ABVS was 10.9, 11.1, and 11.5 min, respectively. No significant difference was found in the total scanning time between any two of the three examiners.ConclusionThe four-scans technique for the major segments of the breast is thought to be an operator-independent, feasible method for performing automated breast US.

Monitoring of early response to neoadjuvant chemotherapy in breast cancer with 1H MR spectroscopy: Comparison to sequential 2-[18F]-fluorodeoxyglucose positron emission tomography

To assess the efficacy of 1H MR spectroscopy (MRS) to evaluate early responses to neoadjuvant chemotherapy in breast cancer patients, as compared to that of the standardized uptake value (SUV) in 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET).

Breast-conserving surgery after chemotherapy: value of MDCT for determining tumor distribution and shrinkage pattern.

OBJECTIVE For this study, we investigated the usefulness of MDCT in assessing the extent of residual breast cancer after neoadjuvant chemotherapy. To ensure the success of breast-conserving surgery, we evaluated the usefulness of determining the tumor distribution before neoadjuvant chemotherapy and the shrinkage pattern after neoadjuvant chemotherapy. SUBJECTS AND METHODS MDCT before and after neoadjuvant chemotherapy was performed in 46 consecutive patients with 47 locally advanced breast cancers. The distribution pattern of contrast enhancement on MDCT before neoadjuvant chemotherapy was classified into five categories: solitary lesion, grouped lesion (localized lesion with linear, spotty, or linear and spotty enhancement), separated lesion (multiple foci of contrast enhancement), mixed lesion (grouped lesion with multiple foci), and replaced lesion (diffuse contrast enhancement in whole quadrants). RESULTS There was agreement between the MDCT assessment and pathologic findings in 44 (94%) of the 47 tumors. In the partial response group with nonreplaced lesions, MDCT revealed three shrinkage patterns: pattern 1a, concentric shrinkage without surrounding lesions; pattern 1b, concentric shrinkage with surrounding lesions; and pattern 2, shrinkage with residual multinodular lesions. Breast-conserving surgery was performed successfully in 14 patients including complete response cases that were detected on the basis of MDCT findings and partial response cases that were detected on the basis of observation of pattern 1 shrinkage. In all five patients with pattern 2 shrinkage, CT underestimated the residual tumor extent by more than 2 cm. CONCLUSION MDCT classification of tumor distribution before neoadjuvant chemotherapy and of shrinkage patterns after neoadjuvant chemotherapy is important in the preoperative evaluation of patients undergoing breast-conserving surgery.

Preliminary study of early response to neoadjuvant chemotherapy after the first cycle in breast cancer: comparison of 1H magnetic resonance spectroscopy with diffusion magnetic resonance imaging

PurposeThe aim of this study was to assess the efficacy of single-voxel 1H magnetic resonance spectroscopy (MRS) at 1.5 T to evaluate early responses to neoadjuvant chemotherapy after the first treatment in breast cancer patients and to compare it to measurements of apparent diffusion coefficient (ADC) values derived from diffusion-weighted magnetic resonance imaging (MRI).Materials and methodsNine patients with breast cancer who were scheduled to receive neoadjuvant chemotherapy were recruited. MR examination after the first cycle was scheduled for a few days before the administration of the second dose.ResultsTwo patients were excluded from the study because their regimen was changed after the first cycle. MRS before chemotherapy demonstrated the presence of choline (Cho) at 3.22–3.23 ppm in six cases and at 3.27 ppm in one case. Diffusion-weighted MRI before chemotherapy demonstrated a localized high-signal lesion in all cases. The change of the integral value of Cho after the first cycle of chemotherapy showed a positive correlation with the change in lesion size (r = 0.91, P = 0.01), whereas no correlation was observed between the change of ADC values after the first cycle and the change in lesion size (r = 0.45, P = 0.32).ConclusionMRS after the first cycle may be more sensitive to diffusion-weighted MRI to predict the pathological response.