Clinical impact of perinephric fat stranding detected on computed tomography in patients with acute pyelonephritis: a retrospective observational study

Perinephric fat stranding is associated with increased age and stone size but not with serum creatinine in patients with obstructing ureterolithiasis

Previous reports show increased severity of perinephric fat stranding (PFS) with elevated serum creatinine in obstructing ureterolithiasis. We sought to investigate this association with our institution's patient population.We reviewed charts of patients diagnosed with obstructive ureterolithiasis or nephrolithiasis in our emergency department between January and October 2018. Patient demographics, lab results, and computed tomography (CT) imaging were reviewed. A blinded radiologist reviewed all CTs and graded hydronephrosis and PFS. Subjects were stratified by degree of PFS and compared via paired t-test, chi-squared test, univariate analysis, and multivariate analysis.We identified 141 patients; 114 had no-mild (Group 1) PFS, while 27 had moderate-severe (Group 2) PFS. Group 1 had a mean age of 56 (SD = 16.1) and mean stone size of 7.3 mm (SD = 4.22); 77% of the cohort had symptoms under 24 h. Group 2 was older with a mean age of 65 (SD = 16.2, p = 0.01) and mean stone size of 10.1 mm (SD = 6.07, p < 0.01); 50% had symptoms less than 24 h (p = 0.01). PFS did not correlate with change in serum creatinine. Univariate and multivariate analysis showed increasing age increased the odds of moderate-severe PFS by 3.5% (OR = 1.035, p < 0.05) while increased stone size increased the odds of moderate-severe PFS by 13.7% (OR = 1.137, p = 0.01).Although increased PFS correlated with increased age and stone size, no correlation was found with presenting creatinine or change in creatinine. Degree of PFS is likely a poor predictor of renal disease severity in acute ureterolithiasis.

Prognostic value of preoperative radiographic perinephric fat features in renal cell carcinoma patients undergoing surgery

BACKGROUND

We aimed to assess the prognostic importance of perinephric fat features in images of patients with non-metastatic renal cell carcinoma (RCC) undergoing surgery.

METHODS

We enrolled RCC patients who underwent surgical treatment between 2011 and 2019. Two characteristics, including perinephric fat thickness and perinephric fat stranding, were evaluated using preoperative computed tomography or magnetic resonance images. The association between perinephric fat characteristics and disease progression was examined by Kaplan-Meier survival analysis and Cox regression model.

RESULTS

In a multivariate Cox proportional hazards model adjusting for tumor stage, intratumoral necrosis, and neutrophil-to-lymphocyte ratio, we found that patients in the thin perinephric fat group (<1 cm) had a poorer progression-free survival (PFS) compared to the thick perinephric fat group (≥1 cm) (HR 2.8; 95% CI 1.175-6.674, p = 0.02). Additionally, the fat stranding group had a poorer PFS than the non-stranding group (HR 3.852; 95% CI 1.082-13.704, p = 0.037). The non-stranding with thick perinephric fat group exhibits the highest cumulative PFS while the stranding with thin perinephric fat group has the lowest cumulative PFS. In receiver operating characteristic curve analysis, combing these two perinephric fat characteristics with tumor stage can achieve a better discriminatory power than tumor stage alone.

CONCLUSIONS

Our study indicates that the evaluation of image-based perinephric fat features is a simple, straightforward, reproducible tool for predicting RCC prognosis and may assist in preoperative risk stratification.

Early versus delayed ureterolithotripsy following obstructive acute pyelonephritis treatment

BACKGROUND AND OBJECTIVES

There is no recommendation on the timing of ureterolithotripsy after the treatment of obstructive acute pyelonephritis (APN). The effect of early and delayed ureterolithotripsy on postoperative urinary tract infection (UTI) and other complications was investigated.

METHODS

Patients who underwent ureterolithotripsy after obstructive APN treatment between February 2017 and August 2021 were divided into two groups, those operated during hospitalization and those operated within 3 months after discharge. Two groups were compared in terms of stone-free status, postoperative complications, postoperative UTI, and urosepsis rates.

RESULTS

Of the 91 patients included in the study, 68 were in the early ureterolithotripsy group, while 23 patients were in the delayed ureterolithotripsy group. The postoperative UTI rate was significantly higher in patients who underwent early ureterolithotripsy (29.4% vs 8.7%, p = 0.045). Patients with postoperative UTI had a higher moderate/severe perinephric fat stranding (PFS) on non-contrast CT at hospital admission (52.2% vs 29.4%, p = 0.048). Among the laboratory parameters, white blood cells were significantly higher in the group with postoperative UTI (21604.5 vs 14728.9, p = 0.042). In the multivariate analysis, early ureterolithotripsy and moderate/severe PFS were independent predictors for postoperative UTI. In the created model, the probability of postoperative UTI after ureterolitripsy after obstructive APN treatment was 3.5% in patients without risk factors, while this rate was 51.9% in patients with both risk factors.

CONCLUSION

There is no consensus on the timing of stone removal after treatment of obstructive APN. Early ureterolithoripsy and moderate/severe perinephric fat stranding on non-contrast CT are risk factors for postoperative UTI.

Post mortem computed tomography is highly sensitive for pyelonephritis. A radiologic-pathologic correlation series

Pyelonephritis is a potentially lethal disease occasionally encountered in the forensic setting. Post mortem computed tomography (PMCT) is an important investigative tool for the forensic pathologist. In particular, it may be used to document and screen disease prior to traditional autopsy methods. While the sensitivity and specificity of computed tomography for pyelonephritis is well studied in the antemortem clinical setting, the test characteristics of PMCT are not yet described in the forensic pathology literature. A series of all cases of fatal pyelonephritis identified at the Ontario Forensic Pathology Service, over the course of 1 year was studied. Radiologic, clinical and pathologic findings were reviewed. A fulsome autopsy, including histopathologic examination, was considered the gold standard for sensitivity and specificity calculations. A control group consisting of 16 cases without pyelonephritis (ex: opiate toxicity) in which both PMCT and histologic data were available by way of comparison. Sixteen cases of pyelonephritis were identified. Post mortem computed tomographical signs of pyelonephritis included asymmetric renal enlargement, perinephric fat stranding, and ectopic renal air. The most (57%) individually sensitive of these findings was perinephric fat stranding but sensitivity increased to 100% if any of the three signs were present. The control group analysis revealed the specificity of air asymmetry (81%), asymmetric renal enlargement (81%), and fat stranding (69%). PMCT findings may rule in a diagnosis of pyelonephritis, and should prompt the pathologist to grossly and microscopically examine the kidneys.