CT detection of fat retention in the bladder after partial nephrectomy

Imaging of Perirenal and Intrarenal Lymphatic Vessels: Anatomy-based Approach

The lymphatic system (or lymphatics) consists of lymphoid organs and lymphatic vessels. Despite the numerous previously published studies describing conditions related to perirenal and intrarenal lymphoid organs in the radiology literature, the radiologic findings of conditions related to intrarenal and perirenal lymphatic vessels have been scarcely reported. In the renal cortex, interlobular lymphatic capillaries do not have valves; therefore, lymph can travel along the primary route toward the hilum, as well as toward the capsular lymphatic plexus. These two lymphatic pathways can be opacified by contrast medium via pyelolymphatic backflow at CT urography, which reflects urinary contrast agent leakage into perirenal lymphatic vessels via forniceal rupture. Pyelolymphatic backflow toward the renal hilum should be distinguished from urinary leakage due to urinary injury. Delayed subcapsular contrast material retention via pyelolymphatic backflow, appearing as hyperattenuating subcapsular foci on CT images, mimics other subcapsular cystic diseases. In contrast to renal parapelvic cysts originating from the renal parenchyma, renal peripelvic cysts are known to be of lymphatic origin. Congenital renal lymphangiectasia is mainly seen in children and assessed and followed up at imaging. Several lymphatic conditions, including lymphatic leakage as an early complication and acquired renal lymphangiectasia as a late complication, are sometimes identified at imaging follow-up of kidney transplant. Lymphangiographic contrast material accumulation in the renal hilar lymphatic vessels is characteristic of chylo-urinary fistula. Chyluria appears as a fat-layering fluid-fluid level in the urinary bladder or upper urinary tract. Recognition of the anatomic pathway of tumor spread via lymphatic vessels at imaging is of clinical importance for accurate management at oncologic imaging. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

CT features of feline lipiduria and renal cortical lipid deposition

Objectives

The aims of this study were to document the presence and prevalence of feline lipiduria and renal lipid deposition on CT, and to search for associations between the presence of lipiduria and sex, urinary tract abnormalities and urolithiasis.

Methods

The CT examinations of 252 cats were reviewed for the presence of an antigravitational hypodense bubble in the urinary bladder with density values between −180 Hounsfield units (HU) and −20 HU. To identify associations between lipiduria and sex, urinary tract abnormalities and urolithiasis, Fisher’s exact test was used. Renal cortical density measurement was performed in all cats. The Mann−Whitney test was performed to compare renal cortical density between lipiduric and unaffected cats.

Results

A total of 27 domestic cats (10.7%) had CT evidence of lipiduria. Lipiduric cats had a significantly lower renal cortical density than unaffected cats (P <0.01). Male neutered cats had a significantly higher frequency of lipiduria and lower renal cortical density compared with female neutered cats (P <0.01). There was no significant difference between the groups regarding renal, ureteral or urethral abnormalities.

Conclusions and relevance

Lipiduria is a common physiological phenomenon in cats that can be detected on routine CT examinations. Decreased renal cortical density is associated with lipiduria. This may aid in the diagnosis of feline lipiduria and help to differentiate its presence from other pathological depositions and excretions.

Trans-urethral resection of bladder tumor (TURBT) and radiofrequency ablation of renal tumor: Rare etiologies of chyluria

Chyluria is a rare entity which is caused by abnormal communication between the lymphatic system and the urinary tract, which allows the passage of chyle into the urine. Whenever symptomatic, chyluria presents with lower urinary tract symptoms such as dysuria and hematuria. Multiple imaging modalities can aid in diagnosis such as lymphoscintigraphy, retrograde pyelography, CT scan of the abdomen and pelvis, and magnetic resonance imaging. Numerous etiologies are associated with chyluria among which are surgical interventions. Partial and radical nephrectomy have been reported in a number of symptomatic and asymptomatic cases, while radiofrequency ablation of renal tumors has been very rarely reported.

Herein, we report 2 cases of chyluria; one caused by trans-urethral resection of a bladder tumor and another by radiofrequency ablation of a renal oncocytoma. Fat-fluid level in the urinary bladder was seen on both precontrast and postcontrast images of CT scan of the abdomen and pelvis. Cystoscopy demonstrated no evidence of any abnormality of the urinary bladder.

Unipedal Diagnostic Lymphangiography Followed by Sequential CT Examinations in Patients With Idiopathic Chyluria: A Retrospective Study

OBJECTIVE

The objective of our study was to investigate the clinical value of diagnostic lymphangiography followed by sequential CT examinations in patients with idiopathic chyluria.

MATERIALS AND METHODS

Thirty-six patients with idiopathic chyluria underwent unipedal diagnostic lymphangiography and then underwent sequential CT examinations. The examinations were reviewed separately by two radiologists. Abnormal distribution of contrast medium, lymphourinary leakages, and retrograde flow were noted, and the range and distribution of lymphatic vessel lesions were recorded. The stage of idiopathic chyluria based on CT findings and the stage based on clinical findings were compared. Therapeutic management and follow-up were recorded. Statistical analyses were performed.

RESULTS

Compared with CT studies performed after lymphangiography, diagnostic lymphangiography showed a unique capability to depict lymphourinary leakages in three patients. Lymphourinary fistulas and abnormal dilated lymphatic vessels were found in and around kidney in all patients. CT depicted retrograde flow of lymph fluid in 47.2% of patients. The consistency in staging chyluria based on CT findings and clinical findings was fair (κ = 0.455). Twenty-nine patients underwent conservative therapy, and seven underwent surgery. Surgical therapy was superior to conservative management (no recurrence, 85.7% of patients who underwent surgery vs 62.1% of patients who underwent conservative therapy; p = 0.025).

CONCLUSION

From assessing the drainage of contrast medium on unipedal diagnostic lymphangiography and the redistribution of contrast medium on sequential CT examinations, it is possible to detect the existence of lymphourinary fistulas, the precise location of lymphatic anomalies, the distribution of collateral lymphatic vessels, and hydrodynamic pressure abnormality in the lymph circulation in patients with idiopathic chyluria. CT staging of chyluria provides additional information that can be used to guide therapeutic management.