Captopril-enhanced scintigraphy using the method of the expected renogram: improved detection of patients with renin-dependent hypertension due to functionally significant renal artery stenosis

Purpose and design of study: Asymmetric-induced changes of the renogram under angiotensin-converting enzyme inhibition (ACE-I), i.e. lateralization, is probably the most distinctive finding for the detection of haemodynamically significant renal artery stenosis (RAS) in compensated kidney, since bilateral and symmetric patterns are non-specific. In the Consensus statement of diagnostic criteria of renovascular hypertension with captopril renography (Am J Hypertens 1991; 4: 749-755S) ACE-I-induced asymmetry of renograms for the left and right kidney was viewed as vitally important. However, detection of change in split function is a reliable parameter only when using a glomerular tracer, i.e. ^99mTc-DTPA. No indication regarding a more widely used tubular tracer such as ^99mTc-mercaptoacetyltriglycine (^99mTc-MAG3) has been given. Methods and results: the theoretical contralateral curve, called 'expected renogram', was calculated frame by frame from renal curves obtained under ACE-I and one of two baseline curves. The expected renogram was compared with the recorded ipsilateral curve. More than ±2 SD difference between expected and recorded renograms was assumed as suggestive of monolateral or bilateral RAS. Twenty-nine patients with angiographically proven RAS (bilateral in 12) and 20 patients without arteriographic evidence of stenosis were evaluated by post-captopril/baseline ^99mTc-MAG3 renography results obtained with the expected renogram analysis were compared with those obtained by standard criteria which included: improvement of peak time underbase-line conditions, wash-out (75%) time, and monolateral or bilateral residual cortical activity >10%, but asymmetrical, i.e. with >5% change in split function. Compared to the standard evaluation, the use of the expected renogram for the diagnosis of RAS improved the specificity from 70 to 95% (P<0.03) without loss of sensitivity (79.3%). Follow-up data after revascularization were available in 18 scintigraphically positive and six scintigraphically negative patients with RAS. The sensitivity of the expected renogram method referring to short-term (1 month) patient outcome following revascularization was 88.8%. The beneficial effects on blood pressure response persisted in 77% of these patients at 18 months. Notably, four of six scintigraphically negative patients with RAS did not show any short-term benefit from revascularization and the improvement in blood pressure values lasted for 18 months in only one case. Conclusions: The high specificity of the expected renogram method reduces the number of unnecessary invasive procedures. This is a critical point for a low-prevalence disease such as renovascular hypertension.     

Pathomechanisms and the diagnosis of arterial hypertension in pediatric renal allograft recipients

Arterial hypertension is common in pediatric renal allograft recipients. While the causes are multifactorial, including chronic graft rejection, immunosuppressive therapy, and renal vascular disorders, the effect of hypertension on renal allograft function is detrimental. As in adults, if not treated early and aggressively, hypertension may lead to cardiovascular damage and graft failure. Pathophysiological changes in the arteries and kidney after renal transplantation and the impact of receptor regulation have not been studied extensively in children. For identifying children with hypertension following renal transplantation casual blood pressure measurements do not accurately reflect average arterial blood pressure and circadian blood pressure rhythm. Ambulatory 24-h blood pressure monitoring should regularly be applied in transplant patients. The purpose of this review is to analyze pathophysiological aspects of risk factors for arterial hypertension and underline the importance of regular blood pressure monitoring and early therapeutic intervention.     

An experience of single dose captopril renal scintigraphy in the diagnosis and management of bilateral renovascular hypertension

A 41-year-old woman visited our hospital with chief complaint of hypertension which was refractory to multiple antihypertensive drugs. Her blood pressure was 200/140 mmHg and her plasma renin activity was as high as 3.1 ng/ml/hr. Angiography revealed bilateral renal artery stenosis. To determine the laterality of the kidney which were responsible for her hypertension, the 99mTc-DTPA renal scintigraphy with captopril was performed. The estimated GFR of the right kidney was lowered than that of the control, while there was no change in the left kidney. Subsequently Percutaneous Transluminal Angioplasty (PTA) was performed to the right kidney. Postoperatively blood pressure remained elevated as well as serum renin level. 99mTc-DTPA scintigraphy with captopril was repeated and revealed no decrease in the GFR of the right kidney this time, but significant reduction in the GFR of the left kidney. After the second PTA to the left kidney, her blood pressure was finally normalized. Postoperatively GFR of both kidneys was not affected by captopril on renal scintigraphy, and currently she has remained normotensive without medication. 99mTc-DTPA scintigraphy with captopril appears to be a useful method to diagnose the laterality and to evaluate in clinical response to therapeutic intervention.     

Gallium-67 scintigraphy in the diagnosis of renal cortical abscess

Clinical and radiologic diagnosis of a renal cortical abscess is difficult. A plain x-ray of the kidneys, ureters and bladder, an excretory urogram with nephrotomography, nephrosonography and renal angiography may not be helpful in the diagnosis. A case is presented of bilateral polycystic kidneys with a renal cortical abscess of the lower pole of the left kidney. An abscess could not be localized by the routine radiologic procedures. Gallium-67 scintigraphy demonstrated a renal cortical abscess of the left kidney, which was treated successfully by operation.     

Gallium67 scintigraphy in the diagnosis of acute renal disease

67Ga scintigraphy was performed in 44 patients with various biopsy proven forms of renal disease and in a further 64 patients, some with clinically diagnosed renal disease and some with non-renal disorders. Renal uptake of gallium at 48 hours was graded by two blinded observers and by tissue ratios determined by computer. All 11 patients with biopsy proven acute drug-induced interstitial nephritis demonstrated intense, diffuse, bilateral renal 67Ga uptake, a phenomenon observed in only five of the other 30 patients with biopsy proven renal disease and in four of the 64 patients with clinical diagnoses only. No patient with acute tubular necrosis demonstrated significant renal gallium uptake. It is suggested that 67Ga scintigraphy is an excellent screening test for the presence of acute interstitial nephritis and helps to identify which patients with unexplained acute renal failure require renal biopsy.     

Yield of renal arteriography in the evaluation of pediatric hypertension

The prevalence of renovascular disease is estimated to be 3%–5% in pediatric patients with hypertension. The utility of non-invasive imaging tests has not been evaluated in children, and renal arteriography remains the diagnostic test of choice. However, there are no established guidelines for the application of this test and information is not available about the likelihood of detecting an abnormality if an arteriogram is performed in children with hypertension. Therefore, we reviewed the yield of renal arteriography in pediatric patients if the test was performed based on the following two criteria: (1) severe hypertension exceeding the 99th percentile for age and sex or (2) failure to control high blood pressure with one antihypertensive drug. During the period 1983–1998, 28 children (mean age 11.7 years) who satisfied one of the above criteria underwent renal arteriography to investigate hypertension. None of the patients were renal transplant recipients. The average duration of hypertension was 11 months and the peak blood pressure was 168/107 mmHg. The renal arteriogram was abnormal in 12 patients (43%). Unilateral renal artery stenosis was the most-common abnormality. When the patients were divided into two groups – those with an abnormal or normal test result – they did not differ in age, sex, or racial distribution. The peak systolic blood pressure was higher in children with an abnormal renal arteriogram (P<0.05). Among those undergoing the arteriogram on the basis of the first criterion, i.e., severe hypertension, 11 of 23 (48%) studies were abnormal. Five children had an arteriogram based on the second criterion – failure to control the blood pressure with one medication – and in 1 patient (20%) the test was abnormal. We conclude that the prevalence of renovascular disease in a population of hypertensive children subjected to renal arteriography is around 40%. Two clinical criteria – namely severe hypertension or failure to control hypertension effectively with one drug – are useful to guide the application of renal arteriography in children with hypertension. Received: 12 August 1999 / Revised: 24 November 1999 / Accepted: 28 November 1999     

Gamma camera scintigraphy in the diagnosis of lymphocele following renal transplantation

The symptoms and diagnosis of perirenal lymphocele following kidney transplantation are discussed. A case demonstrated by means of i.v. urography and gamma camera scintigraphy is reported. The value of the last mentioned method is stressed.     

Washout urography in the diagnosis of renal hypertension

Washout urography was used as a screening test for 100 hypertensive patients. Eleven patients had renal hypertension. These were 4 cases of unilateral renal artery stenosis, 6 cases of unilateral pyelonephritis and one case of bilateral pyelonephritis with atherosclerosis of the right renal artery. The increase in size of the affected kidneys after Lasix injection was much restricted relative to the normal contralateral kidneys. The test proved valuable for screening cases of renovascular hypertension and unilateral pyelonephritis.     

Single-dose captopril test and captopril renal scintigraphy in the evaluation of renovascular hypertension]

The effectiveness of single-dose captopril test (CP-T) and captopril renal scintigraphy with 99mTc-DTPA (CP-RG) in the diagnosis of renovascular hypertension (RVH) was evaluated in 27 patients with (Group I, 16 patients) or without (Group II, 11 patients) renal vascular disease. Group I consisted of RVH in 8 patients (bilateral in 3, unilateral in 5), arteriovenous malformation in 3, renal artery aneurysm in 4, including 2 with essential hypertension, and asymptomatic renal artery stenosis in 1. Group II consisted of 6 hypertensive patients (2 with essential hypertension and 4 with renal hypertension) and 5 normotensive patients. Sensitivity of CP-T and CP-RG in the diagnosis of RVH was 29% (2/7) and 86% (6/7), respectively, indicating the latter was more sensitive than the former. In 3 patients with bilateral RVH, positive response in CP-RG was observed only in the unilateral kidney. Specificity of CP-T and CP-RG was 86% (6/7) and 100% (5/5), respectively in Group I, 100% (8/8) and 83% (5/6), respectively in 16 hypertensive patients. CP-T and CP-RG before and after the treatment of RVH were evaluated in 4 patients. The change of positive response in CP-T and CP-RG into negative after percutaneous transluminal renal angioplasty (PTA) or surgery were found in 3, all followed by a fall in blood pressure, which was not observed in the other patient with positive response after PTA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gamma-camera scintigraphy in the diagnosis of graft ureter obstruction after renal allograft transplantation

Gamma-camera scintigraphy studies in five patients with graft ureter obstruction are presented. The isotope used was¹³¹I-hippuran^R. The diagnosis was suspected when an accumulation of activity in the pelvic region was seen, and it was in all five patients confirmed at surgery or intravenous urography.     

The role of partial nephrectomy in the treatment of pediatric renal hypertension

PURPOSE: From 5% to 25% of hypertension in children is renovascular compared with only 1% in adults. Although much attention is given to renovascular disease involving the main renal arteries, renin producing renal disease may also be intrarenal, involving abnormalities of the segmental vessels or renal parenchyma. We present our results of partial nephrectomy in this unique group of pediatric patients with hypertension in whom renin dependent hypertension involved only a segment of the kidney. MATERIALS AND METHODS: Six patients 10 months to 16 years old were referred for the evaluation of hypertension. Initial evaluations included computerized tomography, ultrasound, voiding cystourethrography and radionuclide renal scan. Renal arteriography with renal vein renin sampling was performed in 5 patients, of whom 4 underwent selective segmental renal vein sampling. Diagnoses included segmental hypoplasia (Ask-Upmark kidney), reflux associated scarring and renal arteriovenous malformation. RESULTS: In patients who underwent selective segmental renal vein sampling an increased renin level was present in the area of the renal lesion (mean 24.9 ng./ml. per hour, range 9.2 to 40.6) compared to the ipsilateral renal vein (15.6, 114 to 29.8). Three patients had evidence of contralateral suppression of renin secretion. All 6 patients underwent upper, lower or mid segment partial nephrectomy. All patients became immediately normotensive and remained so at a mean 10 years of followup. CONCLUSIONS: Partial nephrectomy provides an excellent nephron sparing cure for segmental renal hypertension. In the pediatric population selective segmental renal vein renin sampling is invaluable for locating the renin producing lesion. As in adults, contralateral renin suppression is predictive of surgical cure.     

Value of DTPA scintigraphy following furosemide injection in the diagnosis of obstruction in renal transplantation

Following development of dilatation on ultrasonography and/or intravenous pyelography in the course of follow-up after renal transplantation, a dilatation due to obstruction must be distinguished from dilatation without obstruction. DTPA scintigraphy is frequently used for the diagnosis of hydronephrosis caused by an anomaly of the pyeloureteric junction. In renal transplantation, this examination is used less frequently. The authors report a prospective study of Lasilix scintigraphy in the diagnosis of obstruction in 30 renal transplant. The results presenting with stasis of their transplant. The results were classified into 4 groups according to O'Reilly's classification and were compared with the course of the stasis. Lasilix scintigraphy demonstrated a specificity of 93% and a sensitivity of 63%. The role of stasis in the deterioration of the renal function of a transplant is difficult to evaluate. In cases of stasis with altered renal function, the authors propose the addition of study of the renal parenchyma by renal biopsy, which excludes rejection and Cyclosporin nephrotoxicity. When the renal biopsy is normal, the kidney should be drained by percutaneous nephrostomy which evaluates the capacity of recovery of renal function and determines the indication for antegrade dilatation or surgical repair.     

Pre- and postcaptopril renal scintigraphy as a screening test for renovascular hypertension in children

We studied the ability of pre- and postcaptopril renal scintigraphy to predict renovascular disease (RVD) in children. Retrospective review of medical notes and radiology reports of all hypertensive children who had had both pre- and postcaptopril renal scintigraphy with [^99mTc] dimercaptosuccinic acid (DMSA) and/or [^99mTc] mercaptoacetyltriglycine (MAG3) and digital subtraction angiography (DSA). 81 children aged 1–18 (median 10) years were studied with 62% (51) having a diagnosis of RVD. Main renal artery disease, intrarenal disease, and both main and intrarenal artery disease were present in 25, 14, and 12 patients respectively. The isotope study accurately diagnosed RVD, confirmed by DSA, in 47% (24 of 51) children, with eight false positive studies. The sensitivity, specificity, and positive and negative predictive values of the isotope study to predict RVD were 48%, 73%, 76%, and 51%, respectively. Pre- and postcaptopril renal scintigraphy was unable to predict RVD in children.     

False diagnosis of renal transplant urinary leakage on scintigraphy with mercaptoacetyltriglycine.

99mTechnetium-mercaptoacetyltriglycine (99mTc-MAG-3) has rapidly become the best isotope for transplant renal scintigraphy because of the excellent anatomical resolution. Because 99mTc-MAG-3 is also sequestered by the liver and excreted into the biliary system, images of the gallbladder and intestinal tract will appear in normal 99mTc-MAG-3 scans, especially on delayed scintigraphs. We describe the clinical interpretation of normal bowel images as urinary extravasation in a renal transplant recipient with a sudden decrease in renal function.     

Gallium scintigraphy in the diagnosis of osteomyelitis

The results in the use of Gallium-scintigraphy for diagnosis of osteomyelitis are reported. The examined cases all had individual problems and the Gallium-67 promised additional information about the nature of the underlying bone process. Because of the different mechanisms for Gallium to accumulate in pathological bone processes it is necessary to know exactly the individual problem of the case to keep the rate of wrong positive results low. Despite of such efforts one should be cautious in using this method in the diagnosis of chronic osteomyelitis.     

Longitudinal relations between obesity and hypertension following pediatric renal transplantation

Obesity and hypertension frequently complicate renal transplantation (RTxp). The objective was to assess relations among obesity, hypertension, and glucocorticoids in pediatric RTxp recipients. A retrospective cohort study was carried out in 141 RTxp recipients, 2–21 years of age, with ≥12 months of follow-up. Body mass index Z-score (BMI-Z), systolic and diastolic blood pressure Z-scores (SBP-Z and DBP-Z), and medications at 1, 3, 6, and 12 months and annually thereafter were recorded. Quasi-least squares regression analysis was used. The prevalence of obesity (BMI ≥ 95th percentile) increased from 13% at baseline to >30% from 3 months onward. Greater glucocorticoid exposure (mg/kg/day) was associated with greater increases in BMI-Z (p < 0.001). This association was greater in males, younger recipients, and those with lower baseline BMI-Z (all interactions p < 0.02). The prevalence of systolic hypertension (SBP ≥ 95th percentile) was 73% at 1 month and  ≥ 40% at all follow-up visits. Greater glucocorticoid exposure (p < 0.001) and increases in BMI-Z (p = 0.005) were independent determinants of SBP-Z over time. Cyclosporine (versus tacrolimus) was independently associated with greater SBP-Z and DBP-Z (p = 0.001). Sustained obesity and hypertension frequently complicated pediatric RTxp. Obesity was an independent determinant of systolic hypertension. Strategies are needed to prevent obesity and its impact on hypertension, cardiovascular disease, and allograft survival.