Sachiko Yuen

Breast carcinomas with strong high-signal intensity on T2-weighted MR images: pathological characteristics and differential diagnosis.

To investigate the histopathological characteristics of breast carcinomas with strong high‐signal intensity (SHi) on T2‐weighted (T2W) MR images (T2‐SHi), and discuss the differential diagnosis between T2‐SHi breast carcinomas and T2‐SHi fibroadenomas.

Fiber-Tracking Method Reveals Sensorimotor Pathway Involvement in Stroke Patients

BACKGROUND AND PURPOSE We tested the feasibility of a new MRI technique that provides visualization of the sensorimotor tracts in vivo in a group of stroke victims. SUMMARY OF REPORT Fourteen patients with small infarctions involving the white matter of the supratentorial brain were evaluated. Sensorimotor tracts on the lesional and contralesional sides were successfully depicted in all cases. The position of the sensorimotor tracts relative to the infarct was in good agreement with clinical symptoms. The overall sensitivity and specificity for sensorimotor tract involvement were 100% and 77%, respectively. CONCLUSIONS Our proposed fiber-tracking method was shown to be a clinically feasible technique that correlates well with clinical symptoms.

Effect of Intravenous Gadolinium-DTPA on Diffusion-Weighted Images Evaluation of Normal Brain and Infarcts

Background and Purpose— Diffusion-weighted imaging (DWI) is usually done before administration of intravenous contrast agents. Repetition of DWI is occasionally necessary after administration, but the effects of contrast material on DWI and apparent diffusion coefficient (ADC) values have not yet been fully examined. The present study assesses whether administration of gadolinium-based contrast material significantly affects DWI and ADC values. Methods— We examined DWI data from 39 patients (mean age, 67.9 years; range, 34 to 87 years) who were evaluated with a stroke protocol at our institute. All patients were scanned at the acute or subacute stages of infarct from 3 hours to 5 days after symptom onset. We obtained DWI images using single-shot echo-planar imaging with a b value of 1000 s/mm2. Patients were injected with 0.1 mmol gadopentetate dimeglumine per 1 kg body weight. We examined the signal-to-noise ratio of the normal brain and the infarct and evaluated the contrast-to-noise ratio of each lesion. In addition, we compared the ADC values calculated from the DWI images before and after administration of contrast. The statistical significance of differences between precontrast and postcontrast administration was determined by use of a paired t test. Results— The signal-to-noise and contrast-to-noise ratios of the DW images were not significantly different before and after administration of contrast agent. The ADC values were slightly lower after administration of contrast agent for both normal brain (P =0.0011) and infarcts (P =0.038). The estimated differences in the ADC values were ≈1.3% and 3.5% for normal brain and infarcts, respectively. Conclusions— The lack of a significant difference between the signal-to-noise and contrast-to-noise ratios of DW images before and after administration of contrast agent indicates the feasibility of postcontrast DWI.

Microperfusion-induced elevation of ADC is suppressed after contrast in breast carcinoma

To investigate the effect of gadolinium (Gd)‐DTPA on the apparent diffusion coefficient (ADC) of breast carcinoma and to analyze the relationship between pre/postcontrast ADC and the degree of contrast enhancement.

MR Imaging of Ventral Thalamic Nuclei

BACKGROUND AND PURPOSE: The Vim and VPL are important target regions of the thalamus for DBS. Our aim was to clarify the anatomic locations of the ventral thalamic nuclei, including the Vim and VPL, on MR imaging. MATERIALS AND METHODS: Ten healthy adult volunteers underwent MR imaging by using a 1.5T whole-body scanner. The subjects included 5 men and 5 women, ranging in age from 23 to 38 years, with a mean age of 28 years. The subjects were imaged with STIR sequences (TR/TE/TI = 3200 ms/15 ms/120 ms) and DTI with a single-shot echo-planar imaging technique (TR/TE = 6000 ms/88 ms, b-value = 2000 s/mm2). Tractography of the CTC and spinothalamic pathway was used to identify the thalamic nuclei. Tractography of the PT was used as a reference, and the results were superimposed on the STIR image, FA map, and color-coded vector map. RESULTS: The Vim, VPL, and PT were all in close contact at the level through the ventral thalamus. The Vim was bounded laterally by the PT and medially by the IML. The VPL was bounded anteriorly by the Vim, laterally by the internal capsule, and medially by the IML. The posterior boundary of the VPL was defined by a band of low FA that divided the VPL from the pulvinar. CONCLUSIONS: The ventral thalamic nuclei can be identified on MR imaging by using reference structures such as the PT and the IML.

Comparison of FDG PET and MRI for evaluating the tumor extent of breast cancer and the impact of FDG PET on the systemic staging and prognosis of patients who are candidates for breast-conserving therapy

BackgroundFDG PET has not yet found a role in the clinical evaluation of the tumor extent of breast cancer. FDG PET has been reported to be useful for evaluating the prognoses of breast cancer patients with more accuracy than conventional imaging modalities. The purpose of this study was to compare the accuracy of FDG PET and MRI for the preoperative assessment of the tumor extent of breast cancer, for evaluating the impact of FDG PET on systemic staging, and also for predicting the prognosis of patients who are candidates for breast-conserving therapy.MethodsThe study was a prospective series of 23 breasts with breast cancer that underwent both FDG PET and MRI before surgery. Systemic staging with FDG PET was also performed. The correlation between the results of these examinations and histological findings was thus examined. The maximum standardized uptake value (SUVmax) of the tumors was investigated in association with the patient prognoses.ResultsWhen evaluating the local tumor extent, the accuracy of FDG PET (43.5%) was significantly lower than that of MRI (91%) (P < 0.001). The sensitivity, specificity, and accuracy of FDG PET regarding the nodal status were 60, 94, and 87%, respectively. No patients demonstrated any distant metastasis, whereas FDG PET gave a false positive in one patient. The mean follow-up period was 61 months. The SUVmax value of the worse prognosis patient group was significantly higher than that of the good prognosis patient group (P = 0.032).ConclusionsFDG PET is not a breast imaging modality for evaluating the local tumor extent, but it is useful for predicting the prognoses of patients who are candidates for breast-conserving therapy.

Neoadjuvant chemotherapy for breast cancer: correlation between the baseline MR imaging findings and responses to therapy

Objective:To retrospectively evaluate the magnetic resonance (MR) imaging findings of breast cancer before neoadjuvant chemotherapy (NAC) and to compare findings of chemosensitive breast cancer with those of chemoresistant breast cancer.Methods:The MR imaging findings before NAC in 120 women undergoing NAC were reviewed. The MR imaging findings were compared with the pathological findings and responses.Results:A complete response (pCR) and marked response were achieved in 12 and 35% of 120 breast cancers in 120 women respectively. Breast cancers with a pCR or marked response were classified as chemosensitive breast cancer. The remaining 64 breast cancers (53%) were classified as chemoresistant breast cancer. Large tumour size, a lesion without mass effect, and very high intratumoural signal intensity on T2-weighted MR images were significantly associated with chemoresistant breast cancer. Lesions with mass effect and washout enhancement pattern were significantly associated with chemosensitive breast cancer. Areas with very high intratumoural signal intensity on T2-weighted images corresponded pathologically to areas of intratumoural necrosis.Conclusion:Several MR imaging features of breast cancer before NAC can help predict the efficacy of NAC.

The role of breast MR imaging in pre-operative determination of invasive disease for ductal carcinoma in situ diagnosed by needle biopsy

ObjectivesTo evaluate whether magnetic resonance (MR) imaging features can predict the presence of occult invasion in cases of biopsy-proven pure ductal carcinoma in situ (DCIS).MethodsWe retrospectively reviewed 92 biopsy-proven pure DCIS in 92 women who underwent MR imaging. The following MR imaging findings were compared between confirmed DCIS and invasive breast cancer (IBC): lesion size, type, morphological and kinetic assessments by ACR BI-RADS MRI, and findings of fat-suppressed T2-weighted (FS-T2W) imaging.ResultsSixty-eight of 92 (74%) were non-mass-like enhancements (NMLE) and 24 were mass lesions on MR imaging. Twenty-one of 68 (31%) NMLE and 13 of 24 (54%) mass lesions were confirmed as IBC. In NMLE lesions, large lesions (P = 0.007) and higher signal intensities (SI) on FS-T2W images (P = 0.032) were significantly associated with IBC. Lesion size remained a significant independent predictor of invasion in multivariate analysis (P = 0.032), and combined with FS-T2W SIs showed slightly higher observer performances (area under the curve, AUC, 0.71) than lesion size alone (AUC 0.68). There were no useful findings that enabled the differentiation of mass-type lesions.ConclusionsBreast MR imaging is potentially useful to predict the presence of occult invasion in biopsy-proven DCIS with NMLE.Key PointsMR mammography permits more precise lesion assessment including ductal carcinoma in situA correct diagnosis of occult invasion before treatment is important for cliniciansThis study showed the potential of MR mammography to diagnose occult invasionTreatment and/or aggressive biopsy can be given with greater confidenceMR mammography can lead to more appropriate management of patients

Moyamoya patients exhibit higher brain temperatures than normal controls.

The balance between heat production (metabolism) and heat removal (blood flow) helps in keeping the temperature of the brain constant. In patients with moyamoya disease, this balance may be disturbed. The purpose of this study was to assess the thermal pathophysiology of the brain in patients with moyamoya disease. The study included 12 consecutive patients with moyamoya disease and 10 controls. Temperature was measured by image postprocessing of diffusion-weighted images. Our noninvasive thermometry showed that the ventricular temperature of moyamoya disease patients was higher than that of normal controls. The mean temperature difference of 1.1°C between the two groups was significant. Patients with moyamoya disease tend to have elevated ventricular temperatures, which may represent a mismatch between cerebral metabolism and perfusion.

CT-based evaluation of axillary sentinel lymph node status in breast cancer: value of added contrast-enhanced study

Purpose: To evaluate the diagnostic reliability of CT-based sentinel lymph node (SLN) size criteria for selecting the candidates for direct axillary dissection without SLN biopsy and to determine the value of added contrast-enhanced study. Material and Methods: Breast cancer patients (n=107) underwent triple phasic (1-min, 3-min, 8-min) contrast-enhanced 5 mm-computed tomography (CT) of the breasts and axillae. In the CT image, the most inferior lymph node in the axilla was designated the SLN. Axillary status was judged based on SLN size criteria. CT density, enhancement rate, and peak enhancement time of each SLN were correlated with histopathological results. Results: SLN size criteria demonstrated a sensitivity of 76% and a positive predictive value of 95% in predicting SLN metastasis. The density values at each scanning time-point were significantly different for metastatic and non-metastatic SLN. However, their enhancement rates differed significantly only at 1 min. Their peak enhancement occurred primarily at 1 min. The use of contrast-enhancement criteria improved the predictive sensitivity, but failed to decrease the false-positive rate of the SLN size criteria. Conclusion: The enhancement rate at 1 min proved to be the most useful parameter in contrast-enhanced CT studies; however, it failed in improving the accuracy of the SLN size criteria.