The value of susceptibility weighted imaging in evaluating ischemia-reperfusion injury of the rabbit kidney / 中华放射学杂志

Objective To explore the value of susceptibility weighted imaging (SWI) in the quantitative analysis of ischemia-reperfusion injury (IRI) of the rabbit kidneys . Methods Thirty New Zealand white rabbits were randomly assigned to IRI group (n=24, operation with clamping) and Sham group (n=6, operation without clamping). Left renal ischemia-reperfusion was performed by occlusion (calmping) of the left renal arterial for 60 minutes, followed by reperfusion. All the rabbits underwent MRI including T2WI and SWI before and 0.5 h, 12 h, 24 h and 48 h after the establishments of models . Three rabbits in IRI group were randomly sacrificed 0.5 h, 12 h, and 24 h after the establishment of model. The rest of the rabbits in IRI group and 6 rabbits in sham group were sacrificed for pathological examination 48 h after the establishment of model All specimen were cut into slices and stained with hematoxylin-eosin (HE). Region of interest ( ROI) was manually created by outlining the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex, then relative signal-to-noise ratio of the kidney (rSNR) to muscle in SWI sequence was recorded. and compared with histopathologic features. One-way ANOVA was performed to compare difference of rSNR to muscle in respective location at 5 time-points between Sham group and IRI group, and the differences between groups were tested using repetitive measure analysis of variance, repetitive measure analysis of variance was performed to compare difference of rSNR to muscle in respective location at respective time-points between Sham group and IRI group. Results rSNR value in the inner medulla 0.5 h, 12 h, 24 h and 48 h after the establishments of models were 0.28 ± 0.04, 0.98 ± 0.14, 0.69 ± 0.07, 0.57±0.06, 0.43±0.03, respectively (F=69.82,P<0.01), the inner stripe of outer medulla at the five time-points 0.08 ± 0.03, 0.57 ± 0.05, 0.32 ± 0.07, 0.16 ± 0.02, 0.04 ± 0.01, respectively(F=16.59,P<0.01), the outer stripe of outer medulla were 0.31 ± 0.04, 0.86 ± 0.09, 0.65 ± 0.07, 0.55 ± 0.06 0.43 ± 0.04(F=67.52,P<0.01), respectively,the cortex 0.05±0.01, 0.80±0.04, 0.68±0.07, 0.47±0.07, 0.36±0.08, respectively(F=118.96,P<0.01). The difference of the rSNR was statistically significant in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex at the five different time-points. The differences between two groups were significant (F=206.29, 14.25, 42.8, 39.12, P all<0.05). The pathological findings in Sham group included normalglomerular structure l, clear cavity of tubular, no interstitial hyperemia and edema. The pathological findings in IRI group demonstated, at 0.5 h after IRI, Bowman's capsule cavity expansion, glomerular shrinkage, swelling of renal tubular epithelial cells, vacuoles degeneration, the tube cavity expansion, interstitial edema and congestion ecta became slender, andat 12 h after IR, Bowman's capsule expansion became more obvious, foam degeneration of renal tubular epithelial cells, apoptosis, partial loss of the brush border of the proximal convoluted tubule, formation of protein cast, and a small amount of inflammatory cells appeared in the renal interstitium, swelling of endothelial cells of the vasa recta, congestion of small vessels, and at 24 and 48 h after IRI, more serious injury of renal tubular in the outer stripe of outer medulla , massive necrosis of renal tubular epithelial cells, apoptosis, parts of the renal tubular had the contour lines, and renal tubular outline, increment in inflammatory cells, red cell and protein cast. Conclusion rSNR of SWI in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex of the kidney varies with the degree of IRI over time, and is consistent with corresponding pathological feature, suggesting SWI is useful imaging tool to detect early damage of renal IRI quantitatively.

Evaluation of Renal Oxygenation Level Changes after Water Loading Using Susceptibility-Weighted Imaging and T2* Mapping

OBJECTIVE: To assess the feasibility of susceptibility-weighted imaging (SWI) while monitoring changes in renal oxygenation level after water loading. MATERIALS AND METHODS: Thirty-two volunteers (age, 28.0 +/- 2.2 years) were enrolled in this study. SWI and multi-echo gradient echo sequence-based T2* mapping were used to cover the kidney before and after water loading. Cortical and medullary parameters were measured using small regions of interest, and their relative changes due to water loading were calculated based on baseline and post-water loading data. An intraclass correlation coefficient analysis was used to assess inter-observer reliability of each parameter. A receiver operating characteristic curve analysis was conducted to compare the performance of the two methods for detecting renal oxygenation changes due to water loading. RESULTS: Both medullary phase and medullary T2* values increased after water loading (p 0.05). Interobserver reliability was excellent for the T2* values, good for SWI cortical phase values, and moderate for the SWI medullary phase values. The area under receiver operating characteristic curve of the SWI medullary phase values was 0.85 and was not different from the medullary T2* value (0.84). CONCLUSION: Susceptibility-weighted imaging enabled monitoring changes in the oxygenation level in the medulla after water loading, and may allow comparable feasibility to detect renal oxygenation level changes due to water loading compared with that of T2* mapping.

Imaging manifestations of mucinous tubular and spindle cell carcinoma of the kindey : a pilot study / 中华泌尿外科杂志

Objective To investigate the imaging characteristics of mucinous tubular and spindle cell carcinoma of the kindey (MTSCC-K).Methods Five cases of pathologically confirmed MTSCC-K were analyzed retrospectively.All patients underwent CT scanning,and 4 cases underwent conventional MR and diffusion weighted imaging (DWI) scanning.MR enhancement ratio for the tumor was calculated according to MR signal intensity of pre-and post-contrast in tumor and apparent diffusion coefficient (ADC) values of tumor and normal renal cortical.Results Two case located in the right kindey,and 3 cases located in the left kindey.The maximum diameter of lesions ranged from 3.2 cm to 7.1 cm.Five cases showed nearly round shape with clear borderline.Pseudocapsule was found in 4 cases,3 cases had necrosis and cystic,and 1 case had calcification.There were no hemorrhage,fat and invasion of adjacent tissue.Isodensity or hypodense tumors were found on plain CT.Isointense or hyperintense tumors were found on plain T1WI,while isointense or mixed-signal tumors were found on plain T2WI.Slightly homogeneous or heterogeneous enhancement was observed on dynamic enhanced CT or MR,and the solid component of tumors showed hyperintense on DWI and hypointense on ADC.The mean CT value of tumor at the plain,cortical and nephrographic phase was 32.6 HU,46.5 HU and 66.5 HU,respectively.The mean ADC value of tumor and normal renal cortical was 1.23 × 10-3 mm2/s and 2.31 × 10-3 mm2/s,respectively.The mean MR percentage of enhancement value of tumor was 32.7％ and 104.9％,respectively.Conclusions The imaging characteristics of MTSCC-K include nearly round shape,pseudocapsule,clear borderline,necrosis,cystic and calcification.There is no invasion of adjacent tissue and seldom malignant appearances.Isodensity or hypodense can be observed on plain CT,isointense or hyperintense on plain T1WI,and a mild continuously enhancement on dynamic enhanced scanning.

The feasibility of susceptibility weighted imaging for assessing renal difference of healthy volunteers after water loading / 中华放射学杂志

Objective To probe the feasibility of susceptibility weighted imaging (SWI) for evaluation of renal blood oxygenation level of healthy volunteers after water loading.Methods SWI of 11 healthy volunteers,acquired before (group 1) and after water loading (group 2),were assessed retrospectively by two radiologists with more than 10 years abdominal work experience independently.In those images of the same section plane derived from two groups,the phase values in cortex ((φ)cor) and medulla ((φ)med),difference between the same vein and surrounding tissue on phase map (△(φ)) were measured using SPIN software package,and the oxygen extraction fraction changes (△OEF) was calculated.The (φ)cor,(φ)med and △(φ) between two groups were compared by paired t test.And the intraclass correlation coefficient (ICC)was used to evaluate the consistency between two radiologists.Results For the radiologist 1,the (φ)cor,(φ)med and △(φ) were (0.046 ±0.019),(-0.014 ±0.003) and (1.3 ±0.4) rad in group 1,and were (0.047 ±0.014),(-0.012 ±0.005) and (1.1 ±0.4) rad in group 2 respectively,and no significant change was found in (φ)cor and (φ)med after water loading (t =-0.589 and-0.206,P ＞ 0.05 in all),except of in △(φ) (t =2.400,P ＜ 0.01).For the radiologist 2,the (φ)cor,(φ)med and △△(φ) were (0.049 ± 0.011),(-0.012 ± 0.004)and (1.5 ±0.4) rad in Group 1,and were (0.046 ±0.017),(-0.011 ±0.003) and (1.3 ±0.2) rad in group 2 respectively,there was no significant change in (φ)cor and (φ)med after water loading (t =0.590 and -0.974,P ＞ 0.05 in all),except of in △(φ) (t =2.760,P ＜ 0.05).Between two radiologists,the ICC of (φ)cor,(φ)med and △(φ) were 0.623,0.472 and 0.328 in group 1 and 0.599,0.442 and 0.445 in group 2 respectively.△OEF decreased about (-4.2 ± 2.3) c％ and (-4.3 ± 2.8) c％ measured by two radiologists respectively,and the consistency is good between two radiologists (ICC =0.784).Conclusion SWI provides a novel method to assess indirectly the oxygenation level of kidney,△OEF is an indicator with suitable reliability.

Correlation between apparent diffusion coefficient value and pathological grading in pT1b clear cell renal cell carcinoma / 中华放射学杂志

Objective To evaluate the correlation of ADC values on 3.0 T MR with the pathological grades in pT1b clear cell renal cell carcinoma(CCRCC).Methods Conventional MR images,ADC values and Fuhrman pathological grading of pT1b CCRCC were performed in 30 patients.Grade Ⅰ and Ⅱ were defined as low-grade group; grade Ⅲ and IV were defined as high-grade group.The differences of ADC values among four different pathologic grades were compared with a one-way analysis of variance. The comparison of ADC values of two different grade groups was performed with t test,and the ROC curve was performed to evaluate the diagnostic efficacy of ADC value. Correlation between pathological gradings and ADC values was assessed with Spearman rank correlation analysis. Results ( 1 ) The mean ADC value of grading Ⅰ ( 10 patients ), Ⅱ ( 8 patients ),Ⅲ ( 7 patients ),IV ( 5 patients ) was ( 0.94 ± 0.11 ) ×10-3 mm2/s,(0.82 ±0.13) × 10-3 mm2/s,(0.68 ±0.09) × 10-3 mm2/s,(0.59 ±0.03) × 10-3 mm2/s,respectively.Significant differences of ADC values among the four grades were present (F =16.422,P =0.000 ).( 2 ) The mean ADC value of the low-grade group was significantly higher than that of the high-grade group(t =5.738,P =0.000).Sensitivity and specificity of diagnosing the low-grade group was 88.9％ and 83.3％ respectively.There was a negative correlation between pathological grading and ADC value ( r =-0.807,P ＜ 0.05). Conclusions The ADC values of pT1b CCRCC have close correlation with pathological gradings.They can be used to predict the degree of tumor malignancy preoperatively and guide surgical planning.