Application of low field magnetic resonance imaging technique in measuring kidney volume of polycystic kidney disease rats in vivo / 第二军医大学学报

Objective To measure the renal volume of polycystic kidney disease rats using low field magnetic resonance imaging (MRI), and to explore its application value in the basic research of polycystic kidney disease. Methods Fifteen Han: SPRD rats with polycystic kidney disease of different ages were subjected to anesthesia, and the kidney volume was measured using low field MRI. The kidney profile was delineated by engineers and clinicians. The imaging method was T1-weighted imaging. The cross section of the kidney was imaged, and the kidney volume was calculated using image processing software. Pearson correlation analysis was used to analyze the correlation between the kidney volume measured by MRI and anatomical volume after dissection, kidney mass, the ratio of kidney mass to body mass, renal function indexes and cyst index. Results The kidney of Han: SPRD rats was clearly observed with low field MRI. The kidney volumes of 15 rats measured by MRI were 1.51, 1.77, 3.54, 6.45, 9.34, 9.38, 3.72, 9.51, 4.95, 5.31, 6.47, 7.01, 5.39, 5.08, and 7.31 cm3, respectively. The anatomical volumes after dissection were 1.50, 1.70, 2.90, 5.00, 7.00, 7.02, 2.50, 7.10, 4.70, 4.90, 6.50, 6.70, 4.20, 4.90, and 7.00 cm3, respectively. The renal volume measured by MRI was highly correlated with the anatomical volume after dissection, kidney mass and the ratio of kidney mass to body mass (goodness of fit [R2] was 0.903 1, 0.912 8 and 0.777 9, respectively), and was also positively correlated with serum creatinine, urea nitrogen and cyst index (correlation coefficients were 0.86, 0.85 and 0.61, respectively). Conclusion Low field MRI can be used to measure kidney volume of polycystic kidney disease rat models in vivo, providing a reference for the basic research of polycystic kidney disease.

Cyst infection in hospital-admitted autosomal dominant polycystic kidney disease patients is predominantly multifocal and associated with kidney and liver volume

Positron-emission tomography/computed tomography (PET/CT) has improved cyst infection (CI) management in autosomal dominant polycystic kidney disease (ADPKD). The determinants of kidney and/or liver involvement, however, remain uncertain. In this study, we evaluated clinical and imaging factors associated with CI in kidney (KCI) and liver (LCI) in ADPKD. A retrospective cohort study was performed in hospital-admitted ADPKD patients with suspected CI. Clinical, imaging and surgical data were analyzed. Features of infected cysts were evaluated by PET/CT. Total kidney (TKV) and liver (TLV) volumes were measured by CT-derived multiplanar reconstruction. CI was detected in 18 patients who experienced 24 episodes during an interval of 30 months (LCI in 12, KCI in 10 and concomitant infection in 2). Sensitivities of CT, magnetic resonance imaging and PET/CT were 25.0, 71.4, and 95.0%. Dysuria (P<0.05), positive urine culture (P<0.01), and previous hematuria (P<0.05) were associated with KCI. Weight loss (P<0.01) and increased C-reactive protein levels (P<0.05) were associated with LCI. PET/CT revealed that three or more infected cysts were present in 70% of the episodes. TKV was higher in kidney-affected than in LCI patients (AUC=0.91, P<0.05), with a cut-off of 2502 mL (72.7% sensitivity, 100.0% specificity). TLV was higher in liver-affected than in KCI patients (AUC=0.89, P<0.01) with a cut-off of 2815 mL (80.0% sensitivity, 87.5% specificity). A greater need for invasive procedures was observed in LCI (P<0.01), and the overall mortality was 20.8%. This study supports PET/CT as the most sensitive imaging method for diagnosis of cyst infection, confirms the multifocal nature of most hospital-admitted episodes, and reveals an association of kidney and liver volumes with this complication.

Need for a nomogram of renal sizes in the Indian population–findings from a single centre sonographic study.

Background & objectives: Renal size is an important parameter used in the diagnosis and follow up of renal diseases. However, while making decisions, clinicians must be aware of the dependence of these dimensions on the ethnicity of the individual, independent of anthropometric indices. There is no established nomogram for renal sizes in the Indian population. The aim of this study was to assess the applicability of oft-quoted ranges of normal renal sizes in our population. Methods: Renal dimensions including length, width and parenchymal thickness were sonographically measured in 140 individuals with no renal disease. Analysis was done for differences due to age, gender and laterality. The correlation of renal dimensions with anthropometric parameters like weight, height, body mass index (BMI) and body surface area (BSA) was analyzed. Results: The means of length, width and parenchymal thickness of all 280 kidneys of 140 patients were 9.65 ± 0.63, 4.5 ± 0.42 and 2.04 ± 0.2 cm, respectively. There was a significant difference in parenchymal thickness between the right and left kidneys, while there was no significant right-left difference in length or width. Gender-wise analysis showed significant differences between male and female renal breadths but not length and parenchymal thickness. Age group-wise analysis showed significant decrease in renal length and parenchymal thickness beyond the seventh decade. There was a moderate positive correlation of bilateral renal length with body weight and BSA, and a weak positive correlation with body height and BMI. Interpretation & conclusions: Renal sizes in our population are in contrast to commonly quoted normal values in literature. Conclusions about renal sizes need to be made with reference to nomograms and should not be based upon data from other populations. We also present formulae whereby to derive renal sizes from anthropometric indices in our population.