MRI evaluation of acute renal trauma

We describe the MR findings in a patient with acute renal injury after blunt abdominal trauma associated with perinephric hematoma and urinoma. Both CT and MR findings are described. Active urine extravasation into a perinephric urinoma is demonstrated by serial post-contrast imaging with CT and MRI showing progressively increased attenuation/signal intensity fluid in communication with the collecting system, commencing 2 minutes after contrast administration.     

Renal angiomyolipoma: comparison of MRI and CT results for diagnosis

The aim of this study was to compare the potentials of MRI and CT for characterising renal angiomyolipomas. MRI and CT examinations of 13 adult patients with renal angiomyolipoma were reviewed. Pathological correlation was available for ten patients who underwent nephrectomy or tumourectomy. Negative CT density numbers were demonstrated in 10 cases. MRI depicted high signal intensity areas suggesting fat in 11 cases. A haemorrhagic component was by both CT and MRI in 4 cases and was confirmed by surgery. Fat suppression imaging was performed in 3 cases and confirmed the presence of fat. We conclude that identification of angiomyolipomas can be achieved by MRI, but compared with CT, MRI is more expensive and less available. Therefore MRI should be performed when CT results are equivocal and when direct multiplanar images are necessary for a precise tumour localisation of multiple angiomyolipomas. Correspondence to: M. F. Bellin     

Cystic renal tumors: US and CT findings

Cystic renal tumors represent a variety of lesions in which both solid and liquid components coexist. These lesions may be either benign or malignant and include the multilocular cystic nephroma (MCN), the renal cell carcinoma (RCC), and the papillary adenocarcinoma (PAC). The MCN is a rare neoplasm formed of multiple loculated cystic masses divided by septa. The tumor is benign, although there are some rare reports of malignant cases. The RCC and the PAC may appear with cystic patterns. This is rather uncommon for the RCC, which inside has a unilocular or multilocular cystic appearance, if the necrotic component is large. PAC is an infrequent renal tumor, which has a greater tendency to appear as a large mass with a unilocular large cystic space. The ultrasonography (US) and computed tomographic (CT) features of 27 cystic tumors are presented. Both US and CT allowed the recognition of the cystic components, the septa, and the vegetations. The two imaging techniques made it possible to distinguish the tumors into “unilocular” and “multilocular” masses: the former correspond to RCC and PAC, the latter to MCN and RCC. CT added some information on calcified or partially calcified tumors. CT more than US enabled the differentiation between the malignant RCC and the benign MCN for which conservative surgery may be indicated. The two techniques did not allow the differentiation between RCC and PAC, which has different prognostic behavior.     

Ablation of Symptomatic Cysts Using Absolute Ethanol in 11 Patients with Autosomal-Dominant Polycystic Kidney Disease

Objective

To evaluate the effects of cyst ablation with absolute ethanol in autosomal-dominant polycystic kidney disease (ADPKD) patients with symptomatic cysts.

Materials and Methods

Using absolute ethanol, cyst ablation was performed in 11 patients with documented ADPKD who suffered cyst pain refractory to medical treatment. An ethanol solution was instilled into the largest symptomatic cysts through a catheter. We assessed the therapeutic efficacy of the procedure by tracking subjective pain relief during a 3 to 24-month follow-up period after ablation.

Results

At follow-up, we found that the duration of subjective pain relief was 12 to 24 months in seven patients, 4 to11 months in one, and less than 3 months in three.

Conclusion

Selective ablation of a symptomatic cyst may be a valid option in managing chronic pain caused by one or a few large cysts in ADPKD patients.     

Comparison of CT-guided sclerotherapy with using 95% ethanol and 20% hypertonic saline for managing simple renal cyst.

OBJECTIVE: We wanted to compare the efficacies of 95% ethanol and 20% hypertonic saline (HS) sclerotherapies that were performed in a single session under CT guidance for the management of simple renal cysts. MATERIALS AND METHODS: A prospective series of 74 consecutive patients (average age: 57.6 +/- 8.1 years) with simple renal cysts were enrolled in this study. They were randomized into two groups and 95% ethanol or 20% HS, respectively, corresponding to 25% of the aspiration volume, was injected. Treatment success was determined six months later with follow-up clinical evaluation and performing ultrasonography. RESULTS: The sclerotherapy was accepted as technically successful without major complications in all except two patients who were excluded because of a communication between the simple renal cyst and the pelvicalyceal collecting system. Thirty-six patients in the ethanol group received sclerotherapy with 95% ethanol and 36 patients in the HS group underwent sclerotherapy with 20% HS. The complete regression ratio of the ethanol group was significantly higher (94% versus 72%, respectively) than that of the HS group. There was one patient with partial regression in each group. The failure ratio of the ethanol group was significantly lower (3% versus 25%, respectively) than that of the HS group. CONCLUSION: Ethanol sclerotherapy under CT guidance is a successful and safe procedure and it can be used for the treatment of simple renal cysts. Sclerotherapy with 95% ethanol is more effective than 20% HS sclerotherapy. Sclerotherapy with HS may be an option for patients preferring to undergo a less painful treatment procedure.     

Complications of renal extracorporeal shock wave lithotripsy reviewed

Renal extracorporeal shock wave lithotripsy (ESWL) is a noninvasive and effective method for the treatment of a variety of urinary tract calculi with significantly lower morbidity than both surgical procedures for stone removal (pyelolithotomy/ureterolithotomy) and percutaneous nephrostolithotomy. Though significant, severe complications are rare, ESWL therapy can result in a wide spectrum of tissue injury. This article serves to review the currently known complications of ESWL, which radiologists may encounter, providing an understanding of the potential effects of shock waves on body organs and the resultant functional and morphologic changes that may result.     

CT and US Findings of Multilocular Cystic Renal Cell Carcinoma

Objective

Multilocular cystic renal cell carcinoma (MCRCC) is a recently described variety of renal cell carcinoma with characteristic pathologic and clinical features. The purpose of this study was to analyze the imaging findings of MCRCCs.

Materials and Methods

Ten adult patients with pathologically proven unilateral MCRCC who underwent renal US and CT were included in this study. The radiologic findings were retrospectively evaluated for cystic content, wall, septum, nodularity, calcification and solid portion by three radiologists who established a consensus. Imaging and postnephrectomy pathologic findings were compared.

Results

All patients were adults (six males and four females) and their ages ranged from 33 to 68 years (mean, 46). On US and CT images, all tumors appeared as well-defined multilocular cystic masses composed of serous or complicated fluid. In all patients, unenhanced CT scans revealed hypodense cystic portions, and in four tumors, due to the presence of hemorrhage or gelatinous fluid, some hyperdense areas were also noted. In no tumor was an expansile solid nodule seen in the thin septa, and in only one was there dystrophic calcification in a septum. Small areas of solid portion constituting less than 10% of the entire lesion were found in six of the ten tumors, and these areas were slightly enhanced on enhanced CT scans. In all patients, imaging and pathologic findings correlated closely.

Conclusion

On US and CT images, MCRCC appeared as a well-defined multilocular cystic mass with serous, proteinaceous or hemorrhagic fluid, with no expansile solid nodules in the thin septa, and sometimes with small slightly enhanced solid areas. Where radiologic examinations demonstrate a cystic renal mass of this kind in adult males, MCRCC should be included in the differential diagnosis.     

Pitfalls in the ultrasound diagnosis of upper urinary tract obstruction

Evaluation for possible obstruction of the upper urinary tract with ultrasound can be complicated by pitfalls. Representative examples of pitfalls are reviewed and illustrated in this essay. Since both overdiagnosis and underdiagnosis of urinary obstruction can lead to grave consequences, one must be aware of these pitfalls when performing and interpreting renal ultrasound studies.     

Large egg-shell-like calcified cyst in a case of renal cell carcinoma

A serendipitous case is reported of a large egg-shell-like calsified renal mass woithout irregularities covering a solid nodule suggestive of a renal cell carcinoma on CT. This was confirmed after radical nephrectomy. Correspondence to: R. Oyen     

Spontaneous gas formation in a sterile renal cell carcinoma

Sterile gas formation is a common sequela of therapeutic transcatheter embolization of tumors. We report a patient who spontaneously developed gas collections within an uninfected renal cell carcinoma with a computed tomographic appearance very similar to that seen following embolization. Possible mechanisms for sterile gas formation are discussed.     

Cystic renal masses: Usefulness of the bosniak classification

To determine the usefulness of the Bosniak classification of cystic renal masses, the computed tomographic (CT) and ultrasound findings of 16 pathologically proven cystic renal masses were retrospectively reviewed. All imaging studies were reviewed and categorized utilizing the Bosniak classification without knowledge of the final pathologic diagnosis. There were no category I lesions (classical simple cyst), four category II (minimally complicated), seven category III lesions (more complicated), and five category IV lesions (probable malignant). All category II lesions were benign, all category IV lesions were malignant. Of the seven category III lesions, three were benign and four were malignant. We conclude that the Bosniak classification is extremely useful in the management of cystic renal masses. The opinions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the Uniformed Services University of the Health Sciences, the Department of Defense, or the United States Navy     

MR imaging of adult wilms’ tumor: Correlation with US,CT, and pathology

The magnetic resonance (MR) features of an adult nephroblastoma are presented. The MR appearance is correlated with ultrasound (US), computed tomographic (CT) and pathology. The tumor appeared heterogeneous with calcifications and areas of necrosis and hemorrhage. MR correctly staged the tumor.     

Angiomyolipoma arising in the renal sinus: A difficult radiologic diagnosis

We report a case of angiomyolipoma (AML) occurring in the renal sinus evaluated by intravenous urography (IVU), renal ultrasound (US), angiography, and computed tomography (CT). Imaging features of this lesion are identical to AMLs elsewhere, but preoperative diagnosis was complicated by the unusual occurrence of the tumor in this location in a patient with abdominal pain. Accurate preoperative diagnosis will allow tumorectomy or conservative management.     

Percutaneous intervention in the solitary kidney

The solitary kidney, either after nephrectomy or on a congential basis, may be impaired by infection, stones, obstruction, and trauma. Because of the possibility of further renal compromise by damage of the remaining nephron units, there is reluctance to utilize percutaneous techniques in cases of solitary kidney, and surgery is often used as an alternative. We report 15 cases of solitary kidney in which interventional radiologic techniques (i.e., percutaneous nephrostomy, ureteral stenting, ureteral dilatation, and stone extraction) were attempted for the preservation of renal function, either as a permanent solution or as a temporizing maneuver prior to definitive therapy. In each case, these goals were achieved and there were no complications.     

Percutaneous nephrostomy in pyonephrosis

A series of 76 pyonephrotic kidneys in 73 patients were drained by percutaneous nephrostomy (PN) tube and examined to evaluate the contribution of this technique to the treatment of pyonephrosis. In 71 patients, clinical symptoms disappeared 24–48 h after the procedure. Two patients died from sepsis subsequent to anuria and underlying malignancy. Once the acute phase had remitted, interventional procedures were carried out in 39 cases, and constituted the definitive therapy in 36. In 32 cases, elective surgery was the definitive therapy, including the 3 cases not resolved after interventional procedures. Three patients in whom the obstruction cleared spontaneously following PN needed no additional treatment. Major complications included 6 cases of sepsis, all of which resolved satisfactorily with proper medical therapy.     

0.5 T MRI of small renal masses: value of T2-weighted and Gd-DOTA-enhanced images

We compared the value of T2-weighted and Gd-DOTA-enhanced T1-weighted images for the detection and characterisation of 33 small renal masses (14 clear cell carcinomas, 6 angiomyolipomas, 3 angiomyomas, 4 adenomas, 3 papillary carcinomas, 3 oncocytomas, 1 haemorrhagic cyst). Dynamic enhanced MRI was performed to study the tumoral vascular supply (19 cases). MRI depicted all the masses more than 1 cm in diameter, but missed all the lesions less than 1 cm (4 false-negative). The results of T2-weighted images and Gd-DOTA-enhanced images were similar as regards detection; however, Gd-DOTA-enhanced images depicted more clearly the tumours smaller than 2 cm (11 cases). MRI enabled the characterisation of only 3 masses (2 angiomyolipomas, 1 haemorrhagic cyst). New MRI features are described for oncocytomas (low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, early and marked enhancement on dynamic enhanced MRI). Dynamic enhanced MRI did not contribute to the differentiation of benign from malignant tumours. Correspondence to: O. Hélénon     

Hypoechoic renal pyramids: Sonographic visualization in older children and young adults

The frequency and degree of visualization of medullary pyramids in a normal population, aged 10–29 years, was analyzed. Hypoechoic pyramids were visualized in 42% of right kidneys in subjects aged 10–18 years and in 27% of subjects aged 19–29 years. Prominently hypoechoic pyramids, mimicking the appearance of neonatal kidneys, were seen in an additional 34% of subjects aged 10–18 years and in 16% aged 19–29 years. Prominent pyramids were present in 50% of subjects with renal cortical echogenicity (RCE) equal to liver, but also in 21% of subjects with RCE less than liver. Our study expands the age at which prominently hypoechoic medullary pyramids can be considered a normal finding. This may relate to recent improvements in ultrasound technology.     

Duplex doppler ultrasound in determination of renal artery stenosis

Twenty-six cases of renal artery stenosis were evaluated with Doppler ultrasound using the pulsatile flow index (PFI). To establish normal values, the PFI in 60 renal arteries in 30 healthy volunteers was obtained. Normal values by PFI ranged between 0.48 and 0.71 (mean ± SD: 0.6 ± 0.06). In renal artery stenosis the PFI range was 0.72–0.79. The normal upper limit was 0.71. The PFI failed in three patients; however, an ultrasound examination showed secondary renal disease (two patients with stenosis on both sides with a shrunken kidney on one side, and one patient with hypernephroma on the opposite side). The PFI was normal (14 of 14 patients) in patients without angiographic evidence of stenosis or after successful dilatation.     

Renal changes from extracorporeal shock-wave lithotripsy: evaluation using Doppler sonography

In this study, duplex Doppler sonography was used to evaluate flow changes within renal intraparenchymal vessels induced by extracorporeal shock-wave lithotripsy (ESWL). We have examined 20 patients with caliceal stones before, 1 h and 24 h after ESWL. Doppler waveforms were obtained both from arteries located near the stone and at least at 3 cm from it, and resistive index (RI) measured. A statistically significant increase of the RI (0.079 ± 0.039 mean increase; P < 0.001) was detected 1 h after ESWL in vessels located near the stone. After 24 h, RI tended to normalize (0.056 ± 0.037 mean decrease; P < 0.001). The residual difference (0.022 ± 0.043; P = 0.399) between mean RI values obtained near the stone before and 24 h after ESWL was mainly due to persistent elevated RI values in three patients with ESWL induced hydronephrosis. No significant RI changes were recognized in intraparenchymal vessels located far from the stone. In all patients, Doppler alterations were not associated with morphologic changes of renal parenchyma. Correspondence to: L. E. Derchi     

MR findings in diffuse renal parenchymal disease

This study evaluates the MR appearance of the kidney in diffuse renal parenchymal diseases, using precontrast, and immediate and delayed postgadolinium chelate (Gd), spoiled gradient echo (SGE), and pre- and post-Gd, T1-weighted, fat-suppressed spin-echo MR images to determine if characteristic findings exist for various types of renal disease. One hundred twenty one patients with renal disease underwent MRI. Underlying diagnoses included: (a) glomerular disease (GD), (b) tubulointerstitial disease (TID), (c) microvascular disease (MVD), (d) ischemic nephropathy (INP), (e) obstructive nephropathy (ON), (f) infectious renal disease (IRD), (g) sickle cell disease (SCD), (h) renal cortical necrosis (CN), and (i) renal insufficiency of unknown etiology (UE). MR examinations of 22 patients with normal kidneys (NK) were evaluated as a control group. The presence of corticomedullary differentiation (CMD) demonstrated strong inverse correlation with serum creatinine concentration (SCr) (r=? .568, P <.001). Mean thickness of the renal cortex was 8.4 and 7.8 mm in patients with NK and Gd, respectively. The mean cortical thickness in patients with MVD, TID/Chemo, INP, and ON was 5.2, 5.6, 5.5, and 4.3 mm, respectively, significantly thinner than the renal cortex in the NK and GD groups (P <.01). Irregularity of the renal cortex was more frequent in MVD (60.9%), IRD (62.5%), ON (55.6%), and TID/other (53.8%) than in GD (3.8%) and NK (0%) (P < .01). Diffuse high SI of the entire medulla on delayed postcontrast images was observed in 25(20.7%) of the patients with renal disease and none of the NK group. Although no pathognomonic features were found, certain findings were observed that may correlate with the etiology of the kidney disease and, therefore, assist in the differential diagnosis of renal parenchymal disease.