Complications after Nephron-sparing Interventions for Renal Tumors: Imaging Findings and Management

The two primary nephron-sparing interventions for treating renal masses such as renal cell carcinoma are surgical partial nephrectomy (PN) and image-guided percutaneous thermal ablation. Nephron-sparing surgery, such as PN, has been the standard of care for treating many localized renal masses. Although uncommon, complications resulting from PN can range from asymptomatic and mild to symptomatic and life-threatening. These complications include vascular injuries such as hematoma, pseudoaneurysm, arteriovenous fistula, and/or renal ischemia; injury to the collecting system causing urinary leak; infection; and tumor recurrence. The incidence of complications after any nephron-sparing surgery depends on many factors, such as the proximity of the tumor to blood vessels or the collecting system, the skill or experience of the surgeon, and patient-specific factors. More recently, image-guided percutaneous renal ablation has emerged as a safe and effective treatment option for small renal tumors, with comparable oncologic outcomes to those of PN and a low incidence of major complications. Radiologists must be familiar with the imaging findings encountered after these surgical and image-guided procedures, especially those indicative of complications. The authors review cross-sectional imaging characteristics of complications after PN and image-guided thermal ablation of kidney tumors and highlight the respective management strategies, ranging from clinical observation to interventions such as angioembolization or repeat surgery. Work of the U.S. Government published under an exclusive license with the RSNA. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Quiz questions for this article are available in the Online Learning Center. See the invited commentary by Chung and Raman in this issue.

New imaging tools to measure nephron number in vivo: opportunities for developmental nephrology

The mammalian kidney is a complex organ, requiring the concerted function of up to millions of nephrons. The number of nephrons is constant after nephrogenesis during development, and nephron loss over a life span can lead to susceptibility to acute or chronic kidney disease. New technologies are under development to count individual nephrons in the kidney in vivo. This review outlines these technologies and highlights their relevance to studies of human renal development and disease.

Validity of surrogate measures for functional nephron mass

BACKGROUND

Transplanted nephron mass is an important determinant of long-term allograft survival, but accurate assessment before organ retrieval is challenging. Newer radiologic imaging techniques allow for better determination of total kidney and cortical volumes.

METHODS

Using volume measurements reconstructed from magnetic resonance or computed tomography imaging from living donor candidates, we characterized total kidney (n=312) and cortical volumes (n=236) according to sex, age, weight, height, body mass index (BMI), and body surface area (BSA).

RESULTS

The mean cortical volume was 204 mL (range 105-355 mL) with no significant differences between left and right cortical volumes. The degree to which existing anthropomorphic surrogates predict nephron mass was quantified, and a diligent attempt was made to derive a better surrogate model for nephron mass. Cortical volumes were strongly associated with sex and BSA, but not with weight, height, or BMI. Four prediction models for cortical volume constructed using combinations of age, sex, race, weight, and height were compared with models including either BSA or BMI.

CONCLUSIONS

Among existing surrogate measures, BSA was superior to BMI in predicting renal cortical volume. We were able to construct a statistically superior proxy for cortical volume, but whether relevant improvements in predictive accuracy could be gained needs further evaluation in a larger population.

[Augmented reality for image guided therapy (ARIGT) of kidney tumor during nephron sparing surgery (NSS): animal model and clinical approach]

INTRODUCTION

The main problem in nephron sparing surgery (NSS) is to preserve renal tumors oncological purity during the removal of the tumor with a margin of macroscopically unchanged kidney tissue while keeping the largest possible amount of normal parenchyma of the operated kidney. The development of imaging techniques, in particular IGT (Image Guided Therapy) allows precise imaging of the surgical field and, therefore, is essential in improving the effectiveness of NSS (increase of nephron sparing with the optimal radicality).

AIM

The aim of this study was to develop a method of the three-dimensional (3D) imaging of the kidney tumor and its lodge in the operated kidney using 3D laser scanner during NSS procedure. Additionally, the animal model of visualization was developed.

MATERIAL AND METHODS

The porcine kidney model was used to test the set built up with HD cameras and linear laser scanner connected to a laptop with graphic software (David Laser Scanner, Germany) showing the surface of the kidney and the lodge after removal the chunk of renal parenchyma. Additionally, the visualization and reconstruction was performed on animal porcine model. Moreover, 5 patients (3 women, 2 men) aged from 37 to 68 years (mean 56), diagnosed with kidney tumors in CT scans with a diameter of 3.7-6.9 cm (mean 4.9) were operated in our Department this year, scanning the surface during the treatment with the kidney tumor and kidney tumor after it is removed with a margin of renal tissue. In one case, the lodge of removed tumor was scanned. Dimensions in 3D reconstruction images of laser scans in the study of animal model and the images obtained intraoperatively were compared with the dimensions evaluated during preoperative CT scans, intraoperative measurements.

RESULTS

Three-dimensional imaging laser scanner operating field loge resected tumor and the tumor on the kidney of animal models and during NSS treatments for patients with kidney tumors is possible in real time with an accuracy of -2 mm do +9 mm (+/- 3 mm). The duration of data acquisition by laser scanner and obtain three-dimensional image of the operating field takes an average of 13 seconds +/- 2 seconds. Movements associated with breathing and heart rate did not affect on the quality of the reconstruction. The imposition of the scanned surface texture occurs in real time, allowing you to identify renal parenchymal structures such as renal cortex, pyramids, pyelo-calices complex.

CONCLUSIONS

Imaging control of NSS procedures is possible in animal models and in real time intraoperatively. The comparison of tumor size and the tumor lodge obtained in preoperative CT scans with the measurements during NSS procedure provide the surgeon to assess the extent of macroscopic estimation of the resection. This procedure helps the surgeon in obtaining oncological radicality with saving as much normal tissue kidney as possible. Performance of the imaging methods should be evaluated on a larger group of patients with kidney tumors eligible for NSS treatment.

Serum procalcitonin for prediction of renal parenchymal involvement in children with urinary tract infections: a meta-analysis of prospective clinical studies

OBJECTIVE

To determine by meta-analysis whether serum procalcitonin (PCT) is a useful marker of acute renal parenchymal involvement (RPI) in children with culture-proven urinary tract infection (UTI), as diagnosed by acute-phase DMSA (Tc-99m dimercaptosuccinic acid) renal scintigraphy.

STUDY DESIGN

We searched PubMed and the Cochrane Central Register of Controlled Trials for prospective studies involving children with culture-proven UTIs. Additional eligibility criteria were measurement of serum PCT at presentation and performance of DMSA scintigraphy within 14 days.

RESULTS

Overall, 10 studies eligible for inclusion, involving a total of 627 children, were identified. Half of these studies evaluated children with a first episode of UTI; 8 involved children with febrile UTIs. Using a cutoff value of 0.5 to 0.6 ng/mL, the pooled diagnostic odds ratio of serum PCT for UTI with RPI was 14.25 (95% confidence interval, 4.70 to 43.23). High statistical between-study heterogeneity that could mainly be attributed to 2 studies was observed. The remaining 8 studies uniformly favored PCT use.

CONCLUSIONS

In children with culture-proven UTI, a serum PCT value >0.5 ng/mL predicts reasonably well the presence of RPI, as evidenced by DMSA scintigraphy. PCT may aid in the identification of children with UTI, necessitating more intense evaluation and management.

Functional Significance of Using Tissue Adhesive Substance in Nephron-Sparing Surgery: Assessment by Quantitative SPECT of 99m Tc-Dimercaptosuccinic Acid Scintigraphy

OBJECTIVES

To compare changes in renal function following nephron-sparing surgery (NSS) using tissue adhesive only versus NSS using standard suturing technique, as measured by quantitative SPECT of 99m Tc-dimercaptosuccinic acid uptake by the kidney (QDMSA).

MATERIALS AND METHODS

QDMSA was done before and 3-6 mo after the operation in 32 patients who underwent standard suturing technique and in 24 patients in whom tissue adhesive sealant (19 with albumin glutaraldehyde tissue adhesive [BioGlue]; 5 with CoSeal) was used to close the parenchymal defect. Individual kidney uptake was measured and retrospectively compared between the two groups.

RESULTS

Average tumor diameter was 3.4cm (range: 2.2-6) in the suture group and 3.56 (range: 1.7-6) in the tissue sealant group. In the tissue sealant group following surgery, we observed an average individual renal function loss of 11.49% compared with the suture group in whom an average individual renal function loss of 20.36% (p = 0.02) was measured by 99m Tc-DMSA.

CONCLUSIONS

The use of tissue sealant to close the parenchymal defect during NSS demonstrated a statistically significant advantage in reducing functioning renal loss as measured by the absolute uptake of QDMSA. Further clinical studies are required to establish the role of tissue sealants in NSS.

Segmental disorders of the nephron: histopathological and imaging perspective

Recent advances in molecular genetics and immunocytochemistry have clarified the cell of origin in many renal disorders. Several renal disorders are thought to involve specific segments of the nephron. Renin-secreting tumours arise from juxtaglomerular cells. Clear cell and papillary renal cell carcinoma (RCC) recapitulate the epithelium of the proximal tubules. Oncocytoma and chromophobe RCC differentiate towards Type A and Type B intercalated cells of the cortical collecting duct, respectively. Medullary collecting ducts are the target sites for the development of autosomal recessive polycystic kidney disease, collecting duct carcinoma and medullary carcinoma. Renal papillae are susceptible to unique changes such as necrosis or papillitis. The purpose of our article is threefold: to illustrate the imaging findings of renal disorders that show segmental involvement of the nephron, to describe proximal and distal nephron disorders and to correlate imaging findings of some entities with histopathological features.

Visualization of three-dimensional nephron structure with microcomputed tomography

The three-dimensional architecture of nephrons in situ and their interrelationship with other nephrons are difficult to visualize by microscopic methods. The present study uses microcomputed X-ray tomography (micro-CT) to visualize intact nephrons in situ. Rat kidneys were perfusion-fixed with buffered formalin and their vasculature was subsequently perfused with radiopaque silicone. Cortical tissue was stained en bloc with osmium tetroxide, embedded in plastic, scanned, and reconstructed at voxel resolutions of 6, 2, and 1 microm. At 6 microm resolution, large blood vessels and glomeruli could be visualized but nephrons and their lumens were small and difficult to visualize. Optimal images were obtained using a synchrotron radiation source at 2 microm resolution where nephron components could be identified, correlated with histological sections, and traced. Proximal tubules had large diameters and opaque walls, whereas distal tubules, connecting tubules, and collecting ducts had smaller diameters and less opaque walls. Blood vessels could be distinguished from nephrons by the luminal presence of radiopaque silicone. Proximal tubules were three times longer than distal tubules. Proximal and distal tubules were tightly coiled in the outer cortex but were loosely coiled in the middle and inner cortex. The connecting tubules had the narrowest diameters of the tubules and converged to form arcades that paralleled the radial vessels as they extended to the outer cortex. These results illustrate a potential use of micro-CT to obtain three-dimensional information about nephron architecture and nephron interrelationships, which could be useful in evaluating experimental tubular hypertrophy, atrophy, and necrosis.

Multiphasic multidetector-row CT (MDCT) in detection and staging of transitional cell carcinomas of the upper urinary tract

The aim of this study was to evaluate the potential of multiphasic multidetector-row CT (MDCT) in the detection and staging of transitional cell carcinomas (TCC) of the upper urinary tract. We performed a retrospective chart review of 39 consecutive patients with 41 histologically verified TCC of the renal pelvis and/or the ureter. The urinary tract was examined using MDCT performing unenhanced and contrast-enhanced scans during the corticomedullary (CMP), nephrographic (NP) and pyelographic phase (PP). Tumors were staged according to the TNM classification. MDCT and histopathological findings were correlated. The attenuation of the lesions was documented in Hounsfield units (HU). In MDCT, all 41 TCC--including two multicentric TCC--were detected. TCC confined to the organ (stage 0a-II) was correctly staged in 28/29 tumors (96.6%). Stage III-IV tumors were correctly staged in 8/12 patients (66.6%). Overall, MDCT was accurate in predicting pathologic TNM stage in 36/41 upper urinary tract TCC (87.8%). There was no significant difference of mean attenuation of TCC between CMP, NP and PP (P > 0.05). MDCT with its high spatial and temporal resolution is an accurate tool for detection TCC of the upper urinary tract, with 87.8% accuracy in predicting its stage.

LAPAROSCOPIC PARTIAL NEPHRECTOMY FOR HILAR TUMORS

PURPOSE

Partial nephrectomy for hilar tumors represents a technical challenge not only for laparoscopic, but also for open surgeons. We report the technical feasibility and perioperative outcomes of laparoscopic partial nephrectomy (LPN) for hilar tumors.

MATERIALS AND METHODS

Between January 2001 and September 2004, 25 of 362 patients (6.9%) undergoing LPN for tumor, as performed by a single surgeon, had a hilar tumor. We defined hilar tumor as a tumor located in the renal hilum that was demonstrated to be in actual physical contact with the renal artery and/or renal vein on preoperative 3-dimensional computerized tomography. En bloc hilar clamping with cold excision of the tumor, including its delicate mobilization from the renal vessels, followed by sutured renal reconstruction was performed routinely.

RESULTS

Laparoscopic surgery was successful in all cases without any open conversions or operative re-interventions. Mean tumor size was 3.7 cm (range 1 to 10.3), 4 patients (16%) had a solitary kidney and the indication for LPN was imperative in 10 patients (40%). Pelvicaliceal repair was performed in 22 patients (88%), mean warm ischemia time was 36.4 minutes (range 27 to 48), mean blood loss was 231 cc (range 50 to 900), mean total operative time was 3.6 hours (range 2 to 5) and mean hospital stay was 3.5 days (range 1.5 to 6.7). Histopathology confirmed renal cell carcinoma in 17 patients (68%), of whom all had negative margins. In 2002 or earlier hemorrhagic complications occurred in 3 patients (12%). No kidney was lost for technical reasons.

CONCLUSIONS

LPN can be performed in select patients with a hilar tumor. The technical feasibility reported further extends the scope of LPN. To our knowledge the initial experience in the literature is reported.

Selective intra-arterial 3-dimensional computed tomography angiography for preoperative evaluation of nephron-sparing surgery

OBJECTIVE

To evaluate selective intra-arterial 3-dimensional computed tomography (3D-CT) angiography as a tool for the preoperative evaluation of nephron-sparing surgery (NSS).

METHODS

Twenty-three patients with renal cell carcinoma indicating NSS underwent selective intrarenal 3D-CT angiography. The time-lapse dual-phase technique was used for simultaneous vascular and urographic visualization. The 3D images were created by the shaded volume-rendering method. The CT attenuation of target structures was measured for quantitative evaluation. The 3D images were visually evaluated for the renal artery, vein, and collecting system using a grading system. Results were statistically analyzed.

RESULTS

The 3D-CT angiography depicted the intrarenal branches of the renal artery and vein and the whole collecting system in most patients. Visualization of the renal artery was significantly correlated to its CT attenuation. Visualization of the renal vein was correlated to its CT attenuation adjusted by the surrounding renal parenchyma.

CONCLUSION

Selective intra-arterial 3D-CT angiography allows the detailed visualization of intrarenal structures.

Differentiation between acute cyclosporine nephrotoxicity and acute tubular necrosis using enalaprilat renal scintigraphy in rats

RATIONALE AND OBJECTIVES

Acute cyclosporine (CsA) nephrotoxicity cannot be easily differentiated from other renal parenchymal complications, such as acute tubular necrosis (ATN), that cause renal function impairment at the early posttransplantation period. The purpose of this study was to differentiate acute CsA nephrotoxicity from ATN using enalaprilat renal scintigraphy in rats.

METHODS

Twenty-six rats were divided into 4 experimental groups: CsA group, who were treated with CsA (50 mg/kg/d) for 2 days; ATN group, who received clamping of both renal arteries for 45 minutes; vehicle group, who were treated with olive oil (1 mL/kg/d) for 2 days; and sham-operated group, who received the same surgical procedure as ATN group without clamping of renal arteries. The baseline study was performed with 300 microCi of technetium-99m diethylenetriaminepentaacetic acid and enalaprilat scintigraphy with 2 mCi of technetium-99m diethylenetriaminepentaacetic acid 5 minutes after intravenous enalaprilat injection (30 microg/kg). The changes of renogram grade and the renal function indices such as T(max), T(1/2), residual cortical activity, and mean transit time between 2 studies were analyzed. Immediately after renal scintigraphy, blood urea nitrogen and serum creatinine levels were measured and renal tissues stained by periodic acid Schiff reaction were examined in each group.

RESULTS

Blood urea nitrogen and serum creatinine levels in the CsA and ATN groups were higher than their control groups (P < 0.05). Histologic study revealed severe ischemic necrosis of tubular epithelium in ATN group, but the other groups remained with essentially normal morphology. After enalaprilat injection, renal function indices became improved in CsA group, whereas they deteriorated in ATN group. The renogram grade was decreased in CsA group and increased or unchanged in ATN group after enalaprilat injection. The T(max), residual cortical activity, and mean transit time ratio were statistically different between the 2 groups on enalaprilat study (P < 0.05).

CONCLUSIONS

These results suggest that enalaprilat renal scintigraphy could be used clinically in differentiating acute CsA nephrotoxicity from ATN after renal transplantation.

Nephron-sparing surgery in multiple bilateral angiomyolipomas

We report on a 17-year-old white woman with multiple bilateral renal angiomyolipomas (AMLs) in the absence of tuberous sclerosis. Multiple hyperdense lesions were detected in both kidneys by sonography. A computed tomography (CT) scan confirmed mainly fatty tissue. Sparing as much functional tissue as possible, eight AMLs of the right kidney were resected. The largest removed tumour measured 7 x 4 x 2.4 cm. Renal function was completely preserved. An AML is a benign, generally unilateral renal tumour. Treatment is necessary in cases of flank pain, spontaneous bleeding, obstruction by tumour growth and tumours exceeding 4 cm in diameter. Patients who present are often symptomatic due to pain, retroperitoneal bleeding or haematuria. An AML occurs either sporadically or in association with tuberous sclerosis. Bilateral or unilateral multiple AMLs are rare.

Is deconvolution applicable to renography?

The feasibility of deconvolution depends on many factors, but the technique cannot provide accurate results if the maximal transit time (MaxTT) is longer than the duration of the acquisition. This study evaluated whether, on the basis of a 20 min renogram, it is possible to predict in which cases the MaxTT will exceed 20 min. Renograms of various shapes were simulated by convolution of a plasma disappearance curve and various created retention functions with a mean transit time (MTT) ranging from 3 to 23 min. The values of MaxTT were then derived from the created curves and compared to three parameters of transit measured on the renograms: the time to reach the maximum of the curve (Tmax), the output efficiency at 20 min (OE20), and the normalized residual activity at 20 min (NORA20). The proportion of retention functions (n=390) with MaxTT>20 min increased with increasing Tmax (e.g. 9% for 6< or =Tmax<10 min, and 34% for 11< or =Tmax<15 min), increasing NORA20 (e.g. 20% for 1.4< or =NORA20<3.0, and 84% for 3.0< or =NORA20<5.0) and decreasing OE20 (19% for 50% <OE20< or =75%, and 76% for 25% <OE20< or =50%). Use of Tmax, OE20 and NORA20 doesn't allow the differentiation of cases with a MaxTT longer or shorter than 20 min. Deconvolution can paradoxically only be used in cases of normal transit.

Double-phase helical CT of small renal parenchymal neoplasms: correlation with pathologic findings and tumor angiogenesis

PURPOSE

To correlate the enhancement pattern of double-phase helical computed tomography (CT) of small renal parenchymal neoplasms with pathologic findings and tumor angiogenesis, and evaluate whether the enhancement pattern would be useful in differentiating the histomorphologic types of small renal parenchymal neoplasms.

MATERIALS AND METHODS

Double-phase helical CT (5 mm slice) of the corticomedullary phase (CMP) and late nephrographic phase (NP) was performed in 40 surgically resected renal neoplasms <3.5 cm. The patterns of CT attenuation value and homogeneity were correlated with the subtypes of neoplasms, microvessel density, and the existence of intratumoral necrosis or hemorrhage.

RESULTS

Clear cell renal cell carcinomas (RCC) (n = 29) showed a peak attenuation value in the CMP of >100 HU [Hounsfield units]. Chromophobe cell RCC (n = 2) showed a peak attenuation value in the CMP of <100 HU. Papillary RCC (n = 5) showed a gradual enhancement with the attenuation value in the CMP of <100 HU. However oncocytomas (n = 2) and metanephric adenomas (n = 2) also showed patterns similar to these subtypes of RCC. The degree of enhancement in the CMP correlated with microvessel density (r = 0.87). All tumors with an homogeneous enhancement pattern did not show necrosis or hemorrhage on histologic specimen.

CONCLUSION

The enhancement pattern in double-phase helical CT was different among the subtypes of RCC, and correlated with microvessel density or the existence of intratumoral necrosis or hemorrhage. However it did not differentiate between RCC and other solid tumors.

Familial juvenile nephronophthisis. An ultrasonographic follow-up of seven patients

PURPOSE

To evaluate progressive US changes in the kidneys of patients with familial juvenile nephronophthisis (NPH), an autosomal recessive progressive kidney disease with polyuria, polydipsia, anemia and growth retardation.

MATERIAL AND METHODS

The data from 29 US investigations of 5 boys and 2 girls comprised findings relating to kidney size, echogenicity of the kidney parenchyma, visualization of the corticomedullary junction, and the parameters of renal cysts.

RESULTS

In the early stages of NPH, when the serum creatinine values were between 134 and 370 micromol/l, the corticomedullary differentiation was weak in 6 patients, the echogenicity of the kidney parenchyma was equal to or greater than that of the liver in 5 patients, and 6 patients had developed renal cysts. The findings became more intensive with the progression of NPH. The size of the kidneys remained normal in 4 patients.

CONCLUSION

Renal US reveals characteristic changes already in the early stages of NPH and should therefore be an important part of the diagnostics of NPH because no specific diagnostic test is as yet available.

Nephron sparing surgery for de novo renal cell carcinoma in an allograft kidney: a case report

De novo renal cell carcinoma in a renal allograft is rare and has special implications in renal transplant recipients. We describe a patient with a renal allograft who developed a de novo renal cell carcinoma in the functioning renal allograft 258 months after transplantation. The patient underwent enucleation of the tumor because preoperative MRI showed it was well-encapsulated. A DNA banding study showed that the tumor originated from the donor. Indications for conservative renal surgery in renal cell carcinoma have been increasing. Accordingly, 1 option in the treatment of de novo renal cell carcinoma in a functioning renal allograft is enucleation as a method of nephron sparing surgery.

High-resolution ultrasonography in the differential diagnosis of cystic diseases of the kidney in infancy and childhood: preliminary experience

Autosomal recessive polycystic kidney disease, autosomal dominant polycystic disease, and glomerulocystic disease may all appear in the perinatal period as bilaterally enlarged echogenic kidneys. Current ultrasonographic equipment can better demonstrate the underlying pathologic state and assist in the differentiation of these conditions. The primary abnormality in autosomal recessive polycystic kidney disease is at the level of the collecting ducts, which are dilated and saccular. The nephrons remain normal. These dilated ectatic tubules are seen in their usual distribution as a radial array, with major ducts being perpendicular to the renal capsule, in both the renal cortex and the medulla. The peripheral renal cortex does not normally contain collecting ducts and remains unaffected in patients with mild disease. Autosomal dominant polycystic disease is characterized by cystic changes involving both the nephron and the collecting ducts. The nephron may become cystic at any point. Multiple discrete cysts of varying sizes are seen in both the renal cortex and the medulla in the severely affected infant. Subcapsular cysts are seen regularly. Glomerulocystic disease is an unusual sporadic condition characterized by the cystic dilation of the space of Bowman and the proximal convoluted tubule. On ultrasonographic examination tiny, isolated cysts, usually smaller than those occurring in autosomal dominant polycystic kidney disease, are seen in the echogenic renal cortex and may extend to the periphery of the kidney. No cysts are seen in the renal medulla. Correlation between pathologic findings and sonographic images is of value in correctly diagnosing these conditions.

Renal involvement in von Hippel-Lindau disease

Renal involvement in von Hippel-Lindau (VHL) disease has emerged as the most prevalent cause of death in this hereditary disorder. In a group of 43 VHL patients (23 unrelated families) with renal lesions we examined whether severity of renal disease is affected by parental inheritance and VHL subtype (1, without pheochromocytoma; 2, with pheochromocytoma). We also tested whether and how nephron-sparing surgery could be applied. Renal involvement comprised multiple cysts and bilateral and multifocal carcinomas (RCC) which were detected by screening in 38 patients, at 30.5 (14 to 62) years of age. The severity of the renal disease was similar in VHL type 1 (79% of the pedigrees) and 2 (21%). It was not influenced by the sex of the carrier. Twenty-nine patients were operated on at a mean age of 33.6 years: 21 patients (28 kidneys or 61% of all operated kidneys) underwent nephron-sparing surgery, 4 had complete ablation of involved kidneys and thus required dialysis, 3 had uninephrectomy and 1 had cyst fenestration. Vascular thrombosis was the most severe early complication. It occurred in 4 of 9 kidneys treated by ex vivo surgery. During a median follow-up of 29 months, local recurrence occurred in 5 of 21 (24%) patients treated by nephron-sparing surgery, whereas 2 developed metastasis. Chronic renal failure (creatinine > 120 mumol/liter) affected 11 patients; in 9 of them, it was due to sequelae of surgery. In conclusion, screening of RCC and nephron-sparing surgery are of value in VHL patients. However, indications of ex vivo surgery should be drastically restricted and renal sequelae are not uncommon. Renal followup is required because of the risk of recurrence.

Renal microradiography of experimental ureteral obstruction in the rabbit

Microradiography of nephrons in kidneys perfusion-fixed with glutaraldehyde permits examination of large numbers of nephrons. This technique was applied to rabbits between one and 14 days following unilateral ureteral ligation. Kidneys without ureteral occlusion served as controls. By two days after ureteral obstruction there was dilatation of the ducts of Bellini and papillary collecting ducts. At three to four days there was splaying and tortuosity of the loops of Henle. By eight to 10 days the proximal straight tubules were noted to be dilated and helically twisted. After two weeks of ureteral obstruction there was dilatation of Bowman's space with encroachment on the glomerular capillary tuft. At this time many proximal convoluted tubules began to show atrophic changes. These morphologic alterations may due in part to back pressure on the nephrons, with retrograde progression as the duration of urinary tract obstruction is increased. The distal convoluted tubule and the descending limb of the loop of Henle were not noted to be abnormal during the study.

A microradiographic study of nephrons in mercuric chloride-induced acute renal failure in the rabbit

Microradiography of nephrons was performed on glutaraldehyde-perfusion-fixed kidneys from rabbits injected with mercuric chloride. Kidneys were studied at intervals after injection of the toxin and compared with controls. All mercury-injected animals developed acute renal failure, determined by a rise in serum creatinine. At 6 hours, small filling defects were seen in proximal straight tubules, arising from the wall, and by 24 hours, widespread tubular obstruction was noted. By 12 hours, dilatation of Bowman's space and compression of the glomerular tuft were seen. At 18 hours, preferential channels in the glomerular capillary loops were found, and by 24 hours, there was paraglomerular shunting. No changes were noted in afferent or efferent arterioles. These findings may be related to the decreased glomerular filtration rate seen in acute nephrotoxic renal failure and suggest a role for tubular obstruction in the pathophysiology of this disorder.

Nuclear imaging supplementary to urography in obstructive uropathy

In 50 patients with obstructive uropathy, nuclear imaging supplementary to excretory urography did not improve the detection of obstruction or the determination of the site or etiology of the lesion. However, rapid sequential radionuclide images showed decreased renal perfusion in 64%, more frequently than did an obstructive nephrogram (40%); this finding appeared to occur with more severe degrees of obstruction. Functional impairment of the obstructed kidney was demonstrated more often with 131I Hippuran (o-iodohippurate sodium) (91%) than with 99mTc glucoheptonate (68%) or excretory urography (66%). Neither nuclear nor urographic studies could predict the degree of functional recovery of the kidney until the increased intrapelvic pressures was relieved.

Microangiography in the perfusion-fixed rabbit kidney: a single injection technique for the study of the nephron

Through the modification of a technique developed by Beeuwkes, microangiography, using barium sulfate, was performed on rabbit kidneys following perfusion fixation with gluteraldehyde. Gluteraldehyde is a rapid fixative which preserves tissues while creating few artifacts on the electron microscopic level. The vessels and tubules are preserved in an open-lumen state with sufficient hardness to resist the artifacts caused by high pressure renal artery injections. By injecting barium sulfate at high pressure through the renal artery it is postulated that microruptures are created in the glomerular tuft. This leads to opacification of the tubules and the demonstration of various anatomic configurations. Low pressure injections were used to selectively demonstrate the vascular anatomy. This method allows the demonstration of the vascular and tubular anatomy without specialized techniques. The mechanism of failure of opacification of the renal vein on conventional microangiography are discussed.