Serial quantitative 99mTc DTPA imaging in CMV-associated renal allograft dysfunction

Two cases of cytomegalovirus associated renal allograft dysfunction were monitored by serial 99mTc DTPA imaging and cytomegalovirus specific fluorescent antibody tests. One case of primary cytomegalovirus disease associated with pneumonitis, hepatitis and pyrexia occurred 25 days after transplantation. The second case, due to cytomegalovirus reactivation/reinfection had fewer symptoms and occurred 78 days following transplantation. 99mTc DTPA perfusion index at the height of the cytomegalovirus associated illness remained unaltered in both cases, and did not suggest the presence of acute rejection. This non-reactive response was associated with a rapid return of graft function. The combined use of these rapid diagnostic tests during suspected rejection episodes may be useful in indicating cytomegalovirus associated allograft dysfunction and preventing the addition of further potentially harmful immunosuppressants.     

Captopril-enhanced 99mTc DTPA Scintigraphy in the Detection of Renal-artery Stenosis

The value of captopril-enhanced ^99mTc DTPA scintigraphy as ascreening test for renovascular disease was prospectively studiedin 44 hypertensive patients suspected to have renal-artery stenosis.Renal impairment (plasma creatinine >130umol/l) was presentin 29 patients. At angiography 13 patients had unilateral stenosis,two bilateral stenosis, and 29 patients had no renovasculardisease. Captopril induced a fall in split renal function inthe kidney ipsilateral to the stenosis in all patients withunilateral disease (mean 52 ± 23% to 44 ± 21%of total renal function; P <0.001). A positive captoprilscintigram (defined as a fall of 5% or more in split renal function)had a sensitivity of 85% and a specificity of 72% in the detectionof unilateral renal-artery stenosis. Captopril-enhanced ^99mTcDTPA scintigraphy is a promising non-invasive screening testfor the detection of renal-artery stenosis.     

Simultaneous measurement of extracellular fluid distribution and renal function with a single injection of 99mTc DTPA

BACKGROUND.: The initial rate of renal uptake of ^99mTc DTPA is equal to theproduct of injected dose and the glomerular filtration rate(GFR):plasma volume (PV) ratio, whilst later the plasma clearancerate constant is equal to the GFR:extracellular fluid volume(ECF) ratio. Expressing GFR in terms of body fluid volumes hasseveral attractions, and techniques for measuring it in thisform may be useful. METHODS.: GFR/PV was determined from a Patlak plot in 82 studies in 47patients undergoing routine gamma-camera ^99mTc DTPA renographyand compared with GFR/ECV, determined from the terminal slopeof the plasma clearance curve. RESULTS.: GFR/PV (y) correlated significantly with GFR/ECV (x): y= 3.2.x+5.3 ml/min/l (r=0.82, n=82, P<0.001). The ratio, GFR/PV:GFR/ECVis ECV/PV, which (x) correlated significantly with a regionalestimate (y) of ECV/PV (rECV/rPV) derived from a Patlak plotapplied to a subrenal ROI: y= 0.47x+1.14 (r=0.61, n=52, P<0.001).The initial rate constant of disappearance of ^99mTc DTPA fromthe blood, determined from a ROI over the left ventricle, reflectstracer clearance from plasma to interstitial fluid plus GFR/PV.Subtraction of GFR/PV yields a rate constant which reflectsextrarenal ^99mTc DTPA clearance, Z, as a fraction of PV. A regionalestimate of ^99mTc DTPA clearance from plasma to interstitialfluid, rZ, was derived from the Patlak plot applied to the subrenalROI and expressed in relation to rPV. Z/PV (y) correlated significantlywith rZ/rPV (x): y=2.2x+0.02 min^–1 (r=0.56, n=52, P<0.001).The distribution of ECF between plasma and interstitial fluidwas related to extrarenal ^99mTc DTPA clearance. Thus rZ/rPVcorrelated significantly with ECV/PV (r=0.55, n=52, P<0.001)and Z/PV correlated significantly with rECV/rPV (r=0.6, n=52,P<0.001). There was no correlation between renal functionand extrarenal ^99mTc DTPA clearance or distribution of ECF. CONCLUSIONS.: GFR can be measured in terms of PV and ECF volume from a singleinjection of ^99mTc DTPA. ECV/PV, rECV/rPV, and variables representingthe clearance of ^99mTc DTPA across the microvasculature canbe measured at the same time.     

99mTc DTPA scintigraphy compared with intravenous urography in the follow-up of posterior urethral valves

Twenty-seven patients with posterior urethral valves with varying degrees of renal function underwent both intravenous urography (IVU) and DTPA scan during their follow-up. Although the IVU was successful in excluding obstruction in 31 kidneys, the DTPA scan was successful in 43 kidneys. In addition, the DTPA scan provides quantifiable renal function, exposes the child to a lower radiation dose and has no morbidity compared with an IVU. It is recommended that the DTPA scan should replace the IVU for long-term follow-up and that the latter should be reserved for certain problems.     

99mTc DTPA diuretic renography in the evaluation of surgery in chronic schistosomal and non-schistosomal obstructive uropathy

The selection of patients with chronic obstructive uropathy for surgery is difficult because of problems in identifying true obstruction in a grossly dilated urinary tract. This is especially so in schistosomal (bilharzial) obstructive uropathy. A prospective study of 90 patients (68 with chronic schistosomal and 22 with non-bilharzial obstructive uropathy) was carried out. All patients underwent pre-operative and post-operative radionuclide 99mTc DTPA diuretic renography (RDR). The aims were to assess the value of RDR in the pre- and post-operative management of these patients and whether it could predict the outcome of surgery. Distinctive renogram patterns were identified in patients who required surgical management. These were found useful in monitoring the results and in predicting the outcome of surgery.     

Transfer of 99mTc DTPA and bronchoalveolar lavage findings in patients with asymptomatic extrinsic allergic alveolitis.

An investigation was performed to determine whether symptom free patients with previously diagnosed extrinsic allergic alveolitis had signs of inflammation in the lung. Pulmonary clearance of inhaled technetium-99m labelled diethylene triamine penta-acetic acid (DTPA) was measured in seven patients with a history of extrinsic allergic alveolitis but with no symptoms at the time of the study and in 12 control subjects. Monoexponential clearance curves were obtained in all 12 control subjects. In contrast, lung clearance was abnormal in five of the seven patients: biexponential clearance curves were noted in four and an abnormally rapid monoexponential curve in one. Bronchoalveolar lavage was performed in all patients. Fluid from the second and third aliquots showed increased concentrations of albumin and urea in fluids from the patients, suggesting increased plasma leakage through the alveolocapillary membranes. More eosinophils and more eosinophil cationic protein were also found in the lavage fluid from the patients. The trend towards increased numbers of eosinophils in patients with abnormal lung clearance of DTPA suggests that this may be due to a continuing inflammatory reaction. Lung inflammation was also suggested by the fact that less leukotriene B4 was secreted by cultured alveolar macrophages obtained from patients than by control macrophages. It is concluded that symptom free patients with previous extrinsic allergic alveolitis have continuing alveolar disease as shown by lung clearance and lavage findings.     

Tc-99m DTPA scans in renal allograft rejection and cyclosporine nephrotoxicity

Renal allograft dysfunction arising from rejection or cyclosporine (CsA) nephrotoxicity can currently only be distinguished reliably by allograft biopsy. We have assessed Technetium (Tc)-99m diethylamine pentacetic acid (DTPA) scanning in 30 CsA-treated patients with allograft dysfunction. Scintigrams were performed during 20 biopsy-proved episodes of rejection and during 14 episodes of CsA nephrotoxicity. These results were compared with the scintigrams of 15 allografts showing stable function. Quantitative indices expressing allograft perfusion (flow index) and function (uptake index) derived from the DTPA scintigrams showed no significant differences between the groups of patients with rejection, CsA nephrotoxicity, or stable or improving function. Similarly, the flow and uptake indices of individual allografts obtained during periods of stable or improving function and then during episodes of dysfunction due to rejection or CsA nephrotoxicity did not significantly change. We conclude that Tc-99m DTPA scintigrams are of limited value in the management of allograft dysfunction in patients immunosuppressed with CsA.     

Pelviureteric junction obstruction. The value of a post-micturition view in 99mTc DTPA diuretic renography

Eighty-one 99mTc DTPA renograms were performed in 31 children who had previously undergone pyeloplasty for pelviureteric junction obstruction (PUJ). A post-micturition image following a diuretic stimulus excluded obstruction in 50% of the patients in whom the frusemide T75 was abnormally prolonged beyond 10 min. Evaluating the 99mTc DTPA renogram and the response to a diuretic without both changing the patient's position and ensuring an empty bladder may lead to incorrect diagnosis of PUJ obstruction.     

Clearance of 99mTc DTPA from guinea pig nasal, tracheobronchial, and bronchoalveolar airways.

Technetium-99m labelled diethylenetriamine penta-acetate (99mTc-DTPA) was used to compare small solute absorption (clearance) from nasal, tracheobronchial, and bronchoalveolar airways in anaesthetised guinea pigs. 99mTc DTPA dissolved in saline was superfused through nasal and orolaryngeal catheters on to nasal and tracheobronchial airways; a small particle aerosol of nebulised 99mTc DTPA was delivered to the bronchoalveolar airways through a tracheostomy. Radioactivity over the appropriate region was then determined with a gamma camera. Mucociliary transport of 99mTc DTPA appeared not to contribute to the disappearance of 99mTc DTPA. Time-activity curves were obtained and half life values calculated by fitting a monoexponential equation to the experimental data. A progressive reduction in 99mTc DTPA was recorded from the nasal and tracheobronchial airways and from the bronchoalveolar airway, suggesting that absorption was occurring. The disappearance of 99mTc DTPA was fastest from the bronchoalveolar region, which also had the largest mucosal surface. The similar shape of the retention curves for the nasal and tracheobronchial regions suggests that the characteristics of nasal absorption of 99mTc DTPA could prove applicable to the tracheobronchial region. It is proposed that the present methods are suited for comparing the pharmacology of small solute absorption across nasal, tracheobronchial, and bronchoalveolar airway mucosa.     

Urinothorax demonstrated on 99mTc ethylene dicysteine renal scintigraphy.

Case A 35-year-old Asian male presented with complaints of fever,right-sided pleuritic chest pain and shortness of breath of7 days’ duration, 1 month after a right percutaneous nephrolithotomy(PCNL) by supracostal puncture. On examination, the patientwas pale and tachypnaeic with pulse 120/min and blood pressure150/100 mm Hg. He had stony dullness with decreased     

Indicators of acute rejection on Tc-99m DTPA renal scintigraphy

INTRODUCTION: Specific criteria for diagnosing an acute rejection episode (ARE) are not present on renal scintigraphy. However, a deterioration in renal function observed on serial imaging is suggestive of an ARE during the early posttransplantation period. In this study, we evaluated Tc-99m DTPA renal scintigraphy findings among patients with renal allograft dysfunction. The aim was to define criteria for ARE on a single imaging study alone. MATERIALS AND METHODS: This study included 82 patients with renal allograft dysfunction, each of whom had a specific biopsy-proven pathology. From the background-corrected Tc-99m DTPA renal time-activity curves, the following parameters were computed: the ratio of counts at peak perfusion to that at plateau (P:PL) and the ratio of counts at peak perfusion to that at peak uptake (P:U). The images were inspected visually for excretion patterns and other morphological changes. RESULTS: A specific renogram pattern, that is an increase in perfusion to uptake ratio together with a nearly flat uptake curve and preserved peak/plateau pattern, was observed in 67% of low-grade AREs. In contrast, a flat uptake curve usually occurred together with a loss of peak/plateau pattern in a high-grade ARE. The findings that were highly specific for ARE on visual inspection were little or no collecting system activity, pelvic hypoactivity, and indistinctness of the corticomedullary junction. CONCLUSIONS: Our results indicate that in low-grade ARE, there is decreased filtration relative to perfusion as evidenced by a decrease in the perfusion-to-uptake ratio with loss of a peak/plateau pattern. A hypoactive pelvis with little activity in the collecting systems may be due to edema in the renal interstitium and pelvicalyceal structures.     

99mTc DTPA scanning with diuretic washout. Is it useful in the investigation of obstruction in the presence of gross renal tract dilatation?

Diuretic-enhanced 99mTc DTPA renal scanning aims to determine whether or not a kidney is obstructed. In the presence of gross renal tract dilatation the validity of this technique is questioned. Twenty-eight patients (51 kidneys) with the prune belly syndrome, characterised by gross dilatation and tortuosity of the ureters, were studied. These patients underwent diuretic 99mTc DTPA scanning at the time of diagnosis and at yearly intervals thereafter. Long-term clinical follow-up (3 years) with serial serum creatinine was available in all children. In all cases renal function remained stable and on this basis urinary tract obstruction was excluded. Analysis of the first 99mTc DTPA scan included differential function, whole kidney mean transit time (WKMTT) and the time taken for tracer activity to fall to 75% of peak activity after diuretic stimulus (T75). Using the 99mTc DTPA scan, obstruction can be excluded if the WKMTT is less than 5 min or, in the presence of a prolonged WKMTT, if the diuretic stimulus results in a T75 of less than 5 min. A T75 of between 5 and 10 min is considered equivocal and a T75 exceeding 10 min means that obstruction cannot be excluded. 99mTc DTPA scanning, using these criteria for diagnosis, provided false positive information in 22 kidneys (43%). There were no false negatives. 99mTc DTPA scanning with diuretic washout, using WKMTT and T75 criteria, is not appropriate for the detection of renal tract obstruction in the presence of marked upper renal tract dilatation, since the false positive rate of 43% is unacceptably high.     

Failure of aerosolised 99mTc DTPA clearance to predict outcome in patients with adult respiratory distress syndrome.

The rate of clearance of technetium-99m labelled diethylene triamine pentacetic acid (99mTc DTPA) was measured in 32 patients with adult respiratory distress syndrome to determine if a more rapid clearance rate, possibly reflecting a more severe abnormality of pulmonary function, was associated with a reduced likelihood of recovery from pulmonary failure. Although the mean rate of clearance from lung to blood (T1/2LB) of 99mTc DTPA was more rapid in the patients (T1/2LB = 29 (SEM 3.2) min than in 42 normal subjects (T1/2LB = 59 (1.8)min), there was no difference between the clearance rate in the 18 patients who recovered from respiratory failure (T1/2LB = 31 (5) min) and the 14 who died (T1/2LB = 27 (4) min). Additionally, not all patients studied had abnormally rapid clearance rates. In 12 of the 32 patients the T1/2 fell within the range for normal individuals; this was found more commonly in patients who were predisposed to develop adult respiratory distress syndrome by pancreatitis or massive blood transfusion. These data suggest that a single measurement of 99mTc DTPA clearance in patients with established respiratory failure and adult respiratory distress syndrome is of no value in assessing the likelihood of recovery from this condition.     

Acute pyelonephritis and renal scarring in Kuwaiti children: a follow-up study using 99mTc DMSA renal scintigraphy

The aim of this study was to determine the prevalence of renal scarring in a group of Kuwaiti Arab children with their first documented acute pyelonephritis (APN). Eighty-two Kuwaiti Arab children (10 males and 72 females) who had abnormal ^99mTc DMSA renal scan findings of acute pyelonephritis were prospectively studied with the same imaging modality 6 months after treatment to identify those who developed renal scarring. A micturition cystourethrogram (MCUG) was performed for all of the children 1 month after diagnosis. Children were divided into 3 age groups (<2 years, 2–5 years and above 5 years). The follow-up DMSA renal scans 6 months after diagnosis revealed normalization of renal changes in 56% (46 patients), much improvement with residual renal abnormality in 6% (5 patients), and persistent parenchymal defects in 38% (31 patients). Vesicoureteric reflux (VUR) was found in 32% of children (26/82) and the majority were between grade I and III. Thirteen of those with VUR (50%) developed renal scars on follow-up. Fifty-three percent of the scarred kidneys (19/36) were drained by non-refluxing ureters. In this study, children older than 2 years had less VUR yet were more susceptible to APN and to the development of renal scars. Girls were more prone to developing APN and renal scarring than boys. This work shows that APN is a serious cause for renal scarring in our patients, particularly if associated with other risk factors such as recurrent infections and the female sex.