Renal Damages in Deoxycorticosterone Acetate-Salt Hypertensive Rats: Assessment with Diffusion Tensor Imaging and T2-mapping.

PURPOSE: This study aimed to investigate the feasibility of diffusion tensor imaging (DTI) and T2-mapping to assess temporal renal damage in deoxycorticosterone acetate-salt (DOCA-salt) hypertensive rats and compare the results with histopathologic and immunohistochemical findings. PROCEDURES: After baseline renal magnetic resonance imaging (MRI), 24 out of 30 uninephrectomized Sprague-Dawley rats with DOCA-salt-induced hypertension were divided equally into four groups. Group 1 had renal MRI at weeks 2, 4, 6, and 8, and groups 2, 3, and 4 had MRI at weeks 2, 4, and 6, respectively. The remaining 6 rats were used as sham controls. The renal cortex and outer and inner stripes of the outer medulla were examined over time using fractional anisotropy (FA), apparent diffusion coefficient (ADC), and T2-mapping, and the results were compared with baseline values. The degree of glomerular and tubular injury, endothelial cell thickening, hyaline arteriolosclerosis, macrophage infiltration, microcyst formation, and fibrosis in different zones at different time points in the DOCA-salt rats were compared with controls. RESULTS: Compared with baseline values, DOCA-salt rats demonstrated a significant decrease in renal cortical FA from week 4 to week 8 (0.244 ± 0.015 vs 0.172 ± 0.014-0.150 ± 0.016, P = 0.018-0.002), corresponding to significantly more glomerular damage, arteriolosclerosis, macrophage infiltration, and fibrosis. The DOCA-salt rats had significantly increased cortical ADC and T2 values at weeks 6 and 8 (1.778 ± 0.051 × 10-3 mm2/s vs 1.872 ± 0.058-1.917 ± 0.066 × 10-3 mm2/s; 93.7 ± 4.9 ms vs 98.0 ± 2.9-100.7 ± 4.0 ms, respectively, all P < 0.05), consistent with excessively fluid-filled microcysts (aquaporin-2+). Despite DOCA-salt rats harbored markedly increased fibrosis in outer and inner stripes of the outer medulla at weeks 6 and 8, only nonsignificant decreases in FA were observed in comparison with the controls suggesting that only limited microstructural changes were present. CONCLUSIONS: Renal cortical FA is useful for the early detection and monitoring of renal damage in DOCA-salt hypertensive rats.

Clustered microcalcifications of intermediate concern detected on digital mammography: ultrasound assessment.

To report our experience with targeted-ultrasound in assessing 142 cases with clustered microcalcifications of intermediate concern detected on digital mammography. All cases had histopathologically-proven microcalcifications within the biopsied or surgical specimens. There were 30%[43/142] breast cancers and 70%[99/142] benign lesions. Only 26%[37/142] of clustered microcalcifications were identified on targeted-ultrasound and other findings including negative study (n = 33), anechoic ducts or cysts (n = 70), dilated ducts with echogenic content (n = 13) and hypoechoic nodules (n = 26). There was no statistical difference of the frequency of negative ultrasound between benign and malignant microcalcifications (P = 0.071). However, only 7.1%[5/70] cases with anechoic ducts or cysts were proven to be breast cancer. The frequencies of depiction of dilated ducts with echogenic foci or hypoechoic nodules were significantly higher for malignant microcalcifications (P < 0.001). Ultrasound was significantly more sensitive for the identification of malignant cases but biopsy of clustered microcalcifications is still warranted when targeted-ultrasound revealed negative findings.

31P MR spectroscopic assessment of muscle in patients with myasthenia gravis before and after thymectomy: initial experience.

PURPOSE: To prospectively assess muscle metabolism in myasthenia gravis (MG) patients before and after thymectomy by using phosphorus 31 (31P) magnetic resonance (MR) spectroscopy. MATERIALS AND METHODS: With institutional review board approval and informed consent, resting and dynamic (31)P MR spectroscopy were performed in 14 healthy volunteers (five men, nine women; mean age, 33 years; range, 23-48 years) and 16 MG patients (six men, 10 women; mean age, 37 years; range 18-50 years) before and after thymectomy. Patients were stratified into groups according to the modified Osserman classification: mild-MG group (classes I-IIA) and moderate-to-severe-MG group (classes IIB-IV). Variables compared among the three groups (Kruskal-Wallis test) included the inorganic phosphate (P(i))-adenosine triphosphate (ATP) (P(i)/ATP) ratio, phosphocreatine (PCr)-ATP (PCr/ATP) ratio, P(i)/PCr ratio, muscle pH at resting and at end-exercise ( 31)P MR spectroscopy, rate constant for PCr recovery (k(PCr)), and maximum oxidative capacity (V(max)). These variables were also compared in MG patients before and after thymectomy (Wilcoxon signed rank test). RESULTS: There were no significant differences in resting P(i)/ATP, PCr/ATP, and P(i)/PCr ratios and resting muscle pH among the three groups (control group, 14; mild-MG group, nine; moderate-to-severe-MG group, seven). Comparison of the control group with the mild-MG group and comparison of the mild-MG group before thymectomy with the mild-MG group after thymectomy showed no significant differences in end-exercise P(i)/ATP, PCr/ATP, and P(i)/PCr ratios; end-exercise muscle pH; k(PCr); and V(max). Compared with the control and mild-MG groups, the moderate-to-severe-MG group had significantly higher end-exercise P(i)/ATP and P(i)/PCr ratios and significantly lower end-exercise muscle pH, k(PCr), and V(max) before thymectomy (P < or = .001), but these values showed significant restoration to normal after thymectomy (P = .018). CONCLUSION: Mild-MG group patients have muscle oxidative metabolism similar to that of healthy control subjects, whereas moderate-to-severe-MG group patients have impaired V(max) during exercise and a noticeable shift to glycolytic metabolism, but these abnormalities are reversible after thymectomy.