Perirenal fat stranding on CT: is there an association with bladder outlet obstruction?

Abstract

Objective: To determine the association between perirenal fat stranding (PFS) on CT and bladder outlet obstruction (BOO). Methods: CT scans from 122 patients who had undergone urodynamic study for lower urinary tract symptoms (LUTS) were registered after exclusion of patients with renal or retroperitoneal disease. Images were independently reviewed by two radiologists and compared with those of 244 age-and sex-matched control patients without LUTS. The PFS severity was scored on a fourpoint scale, and the interobserver agreement was assessed with kappa statistics. The severity score and incidence was compared between the groups, and the association with baseline characteristics was analyzed. For the LUTS group, an association between PFS severity and urodynamic and laboratory data was evaluated.Results: PFS was more frequent and more severe in the LUTS group than in the control group (p-value , 0.001); its presence was significantly associated with male gender and older age (p-value , 0.001). PFS was predominantly bilateral in both groups (80.1-93.2%). In the LUTS group, PFS severity scores were significantly correlated with the maximum flow rate, maximum detrusor pressure and estimated glomerular filtration rate (p-value , 0.001). Interobserver agreements were excellent for PFS presence (k 5 0.883) and severity (k 5 0.816). Conclusion: Severe PFS was observed in older, male patients with LUTS. PFS severity was associated with the degree of BOO and impaired renal function. Advances in knowledge: Recognition of PFS on the CT scan may warrant further evaluation of BOO and appropriate management to prevent renal impairment. INTRODUCTIONBladder outlet obstruction (BOO) is a common cause of lower urinary tract symptoms (LUTS) in males, and benign prostatic hyperplasia (BPH) is mainly attributable to BOO in male patients. Multiple mechanisms leading to increased pressure in the urinary bladder and the renal collecting system have been proposed to explain the association between chronic BOO and renal function impairment.1 Renal function impairment secondary to BOO is preventable if cases are recognized early, but it is often difficult to identify patients at risk of renal failure. Urodynamic study is the gold standard for the diagnosis of BOO.2 However, because of its invasiveness, its use for screening purposes is inappropriate.

Oral Therapy for Aerococcus urinae Bacteremia and Thoracic Spondylodiscitis of Presumed Urinary Origin

“…A correlation with urinary outflow obstruction may be an important clue in cases like this one. 25,26 Furthermore, whether the urinary tract truly was the source of the patient' s bacteremia is clouded by the differing antimicrobial susceptibility patterns of the A urinae blood and urine isolates. The simplest explanation for this discordance may be that all the isolates shared a common initial origin but adapted to different environments in the host (perhaps over time) or laboratory, producing phenotypic variation.…”

Prognostic impact of perirenal fat stranding on oncologic outcomes in ureteral urothelial carcinoma

“…Most of the current research regarding secondary signs on CT scans involves the identification of ureteral stones [ 28 29 30 ]. PRFS is defined as linear or curvilinear softtissue attenuation without vascular connection distributed in the perirenal space [ 13 ]. The kidneys are suspended in the perirenal space by the reticular bridging septa connecting the renal capsule to the Gerota's fascia.…”

“…In particular, a meticulous understanding of the various signs identified on preoperative computed tomography (CT) imaging can help surgeons in counseling patients with ureteral UC. Especially, perirenal fat stranding (PRFS), defined as linear or curvilinear soft-tissue attenuation in the perirenal area, has been previously investigated as a secondary sign of ureteral obstruction on CT findings in diverse renal diseases by numerous studies [ 11 13 ]. We hypothesized that PRFS could develop by extravasated urine or lymphatics caused by ureteral obstruction, which could worsen the prognosis of ureteral UC.…”

Assessment of Patient-Related Operative Complexity During Partial Nephrectomy: Comparison of Two Tailored Methods for Measurement of Posterior Perinephric Fat Thickness on Preoperative CT

“…Perinephric fat stranding has been reported as the determinant for predicting operative complexity in the MAP score along with PPFT (8), and the underlying pathophysiology of perinephric "sticky fat" has been thought to be inflammation, desmoplasia, idiopathic fibrosis, or autoimmune response (20). However, from a radiological perspective, the cause of perinephric fat stranding varies from acute to chronic, with a wide spectrum of conditions including acute ureteral obstruction, pyelonephritis, bladder outlet obstruction, postoperative change, acute pancreatitis, and metastasis (21)(22)(23)(24). Moreover, in a histopathologic comparison of patients with or without APF, Dariane et al (17) demonstrated no significant difference in inflammatory infiltration or fibrosis in the perinephric tissue but only significantly larger adipocytes in patients with APF and concluded that the histology of adhesive perinephric fat was unclear.…”