Parenchymal Transit Time Research Articles

The physiological basis of renal nuclear medicine.

Renal physiology underpins renal nuclear medicine, both academic and clinical. Clearance, an important concept in renal physiology, comprises tissue uptake rate of tracer (tissue clearance), disappearance rate from plasma (plasma clearance), appearance rate in urine (urinary clearance) and disappearance rate from tissue. In clinical research, steady-state plasma clearances of para-amino-hippurate and inulin have been widely used to measure renal blood flow (RBF) and glomerular filtration rate (GFR), respectively. Routinely, GFR is measured at non-steady state as plasma clearance of a filtration agent, such as technetium-99m diethylenetriaminepentaacetic acid. Scaled to three-dimensional whole body metrics rather than body surface area, GFR in women is higher than in men but declines faster with age. Age-related decline is predominantly from nephron loss. Tubular function determines parenchymal transit time, which is important in renography, and the route of uptake of technetium-99m dimercaptosuccinic acid, which is via filtration. Resistance to flow is defined according to the pressure-flow relationship but in renography, only transit time can be measured, which, being equal to urine flow divided by collecting system volume, introduces further uncertainty because the volume is also unmeasurable. Tubuloglomerular feedback governs RBF and GFR, is regulated by the macula densa, mediated by adenosine and renin, and can be manipulated with proximal tubular sodium-glucose cotransporter-2 inhibitors. Other determinants of renal haemodynamics include prostaglandins, nitric oxide and dopamine, while protein meal and amino acid infusion are used to measure renal functional reserve. In conclusion, for measuring renal responses to exogenous agents, steady-state para-amino-hippurate and inulin clearances should be replaced with rubidium-82 and gallium-68 EDTA for measuring RBF and GFR.

Renal cortical transit time in the evaluation of prenatally detected presumed pelvi ureteric junction like obstruction: A systematic review.

Introduction:Differentiating nonobstructive from obstructive dilatation of the kidney is a clinical dilemma in prenatally detected hydronephrosis. Many radionuclide renogram parameters have been used to differentiate obstructed from non-obstructed units, including cortical transit time (CTT). We evaluate the role of CTT in identifying obstruction through a systematic review.Methods:A literature search of the MEDLINE, MEDLINE In-Process, and MEDLINE Epub Ahead of Print, EMBASE, Google scholar, Pub Med, and Cochrane Library was done using key words – radionuclide renogram, CTT, parenchymal transit time, cortical transit, renography to identify articles on the subject. The identified articles were assessed for appropriateness and reviewed.Results:The initial search yielded a total of 1583 articles, after adding the articles from references and applying the inclusion and exclusion criteria a total of 28 articles were selected. CTT showed good inter observer agreement in identifying obstruction. The use of CTT as a single parameter for determining the need for surgery and to identify those kidneys which will have functional improvement after surgery has been evaluated and has been found to be useful. CTT is best used in conjunction with ultrasonography to make clinical decisions.Conclusion:The commonly used visual method of estimating the CTT, is a promising parameter for the evaluation of prenatally detected pelviureteric junction obstruction. Further well-designed multicenter prospective studies are needed to establish it as the most specific parameter to differentiate obstructive from nonobstructive dilatation of the pelvicalyceal system.

Assessment of Renal Function Based on Dynamic Scintigraphy Parameters in the Diagnosis of Obstructive Uro/Nephropathy.

This study evaluates the usefulness of parameters allowing assessment of renal function in absolute values in dynamic renal scintigraphy (DRS) with 99mTc-ethylenedicysteine (99mTc-EC) uptake constant (K), mean transit time (MTT), and parenchymal transit time (PTT) in the diagnosis of obstructive uro/nephropathy. The study included 226 people: 20 healthy volunteers, for whom normative values of assessed parameters were determined, and 206 patients. Reproducibility of results obtained by two independent operators, specificity, correlation with estimated GFR (eGFR), and Cohen’s kappa were used to evaluate reliability of assessed parameters. Normative values were as follows: K ≥ 1.6, MTT ≤ 250 s, and PTT ≤ 225 s. Reproducibility of determination of K (rs = 0.99) and MTT (rs = 0.98) was significantly higher than that of PTT (rs = 0.95) (p = 0.001). Specificity was 100% for K, 81% for MTT, and 91% for PTT. Correlation of eGFR with K (rs = 0.89) was significantly higher than with PTT (rs = 0.53) and with split function (SF) (rs = 0.66) (p < 0.0001). Cohen’s kappa was κ = 0.89 for K, κ = 0.88 for MTT, and κ = 0.77 for PTT. In a group of patients where standard DRS parameters are unreliable (bilateral obstructive uro/nephropathy or single functioning kidney), the use of K (the most effective among assessed parameters) changed the classification of 23/79 kidneys (29%). K enables reproducible assessment of absolute, individual kidney function without modifying routine DRS protocol. Diagnostic value of MTT and PTT is limited.

Improved quantification of cerebral hemodynamics using individualized time thresholds for assessment of peak enhancement parameters derived from dynamic susceptibility contrast enhanced magnetic resonance imaging.

PurposeAssessment of cerebral ischemia often employs dynamic susceptibility contrast enhanced magnetic resonance imaging (DSC-MRI) with evaluation of various peak enhancement time parameters. All of these parameters use a single time threshold to judge the maximum tolerable peak enhancement delay that is supposed to reliably differentiate sufficient from critical perfusion. As the validity of this single threshold approach still remains unclear, in this study, (1) the definition of a threshold on an individual patient-basis, nevertheless (2) preserving the comparability of the data, was investigated.MethodsThe histogram of time-to-peak (TTP) values derived from DSC-MRI, the so-called TTP-distribution curve (TDC), was modeled using a double-Gaussian model in 61 patients without severe cerebrovascular disease. Particular model-based zf-scores were used to describe the arterial, parenchymal and venous bolus-transit phase as time intervals Ia,p,v. Their durations (delta Ia,p,v), were then considered as maximum TTP-delays of each phase.ResultsMean-R2 for the model-fit was 0.967. Based on the generic zf-scores the proposed bolus transit phases could be differentiated. The Ip-interval reliably depicted the parenchymal bolus-transit phase with durations of 3.4 s–10.1 s (median = 4.3s), where an increase with age was noted (∼30 ms/year).ConclusionIndividual threshold-adjustment seems rational since regular bolus-transit durations in brain parenchyma obtained from the TDC overlap considerably with recommended critical TTP-thresholds of 4 s–8 s. The parenchymal transit time derived from the proposed model may be utilized to individually correct TTP-thresholds, thereby potentially improving the detection of critical perfusion.

Delayed parenchymal transit time on 99Tcm-DTPA diuretic renography in predicting functional improvement of ureteropelvic junction obstruction after surgery

Objective To evaluate the usefulness of delayed parenchymal transit time (PTT) on 99TcmDTPA diuretic renography as a predictor for functional improvement after Anderson-Hynes dismembered pyeloplasty in patients with ureteropelvic junction obstruction (UPJO).Methods Forty-seven patients (37males,10 females,age (29.7± 10.8) years) with unilateral U PJO were retrospectively analyzed.All patients underwent 99Tcm-DTPA diuretic renography before and after the surgery.Patient age,sex,UPJO location,surgical methods,relative renal function (RRF) of the diseased kidney (uptake ratio of UPJO kidney to both kidneys),and PTT were recorded.Delayed PTT was defined as having one of the following criteria: (1) photopenic pelvis between the second and seventh frame; (2) relatively stable tracer distribution within the kidney between the second to ninth frame with nearly unchanged kidney shape and size; (3) ever increasing activity in the parenchyma; (4) slower clearance from the parenchyma into the pelvis since the second frame compared with the contralateral healthy kidney.The relationship between the above-mentioned factors and RRF improvement (RRFpvst-surgery,-RRFpre-sugery) was analyzed.Paired t test,Kruskal-Wallis and Mann-Whitney rank sum tests and Pearson correlation analysis were used.Results The average RRF of pre-and post-surgery was (40.70± 13.30) ％ and (44.96 ± 12.60) ％,respectively (t =4.19,P ＜ 0.01).RRF improvement between the delayed group (n=16) and normal timely PTT group (n=27) was significantly different: ((11.69±6.52) ％ vs (0.48±2.98) ％,Z=-5.13,P＜0.01).The assessment of delayed or normal PTT could not be determined in 4 patients.No statistically significant differences of RRF improvement were found between pre-surgery RRF ＜ 40％ and RRF ≥ 40％ groups,between left and right UPJO groups,between open surgery and laparoscope groups,between male and female patients (Z =-1.93 to 1.25,all P＞0.05).There was no significant correlation between RRF improvement and patient age (r =0.01,P＞0.05).Conclusion Delayed PTT on 99Tcm-DTPA diuretic renography might be the predictor for functional improvement post surgery in UPJO patients. Key words: Ureteral obstruction; Urologic surgical procedures; Glomerular filtration rate; Radionuclide imaging; DTPA

Diagnostic performance of IAEA software package for the analysis of scintigraphic renal dynamic studies: Preliminary results for semi-quantitative parameters of technetium-99m mercapto-acetyltriglycine renogram in healthy individuals

The aims of this study in healthy individuals were: a) to implement the International Atomic Energy Agency (IAEA) Software Package into analysis of technetium-99m mercapto-acetyltriglycine (99mTc MAG3) dynamic scintigraphy, b) to validate results of renogram parameters against their reference values, and c) to compare different renogram indices of kidney excretion in order to assess whether the clinical information provided by all of them is identical. Study population consisted of 20 healthy subjects who were evaluated by 99mTc MAG3 dynamic scintigraphy for kidney donation. The IAEA software was applied to process the studies. The parameters analyzed were: time to maximum activity (Tmax), time to half maximum (T1/2) of the curves, normalized residual activity at 20 minutes (NORA 20), output efficiency at 20 minutes (OE 20), residual activity (RA), elimination index (EI), whole kidney mean transit time (MTT), mean parenchymal transit time (MPTT) and relative kidney function (RF). Correspondence between OE 20, NORA 20, RA and EI was evaluated by Pearson correlation coefficient and linear regression analysis. The results for normal kidneys were presented as follows: Tmax: 3.4+0.7 min; T1/2:6.1+1.5min; NORA20:0.34+0.09;OE20: 93+2.2%; RA: 26+6.2%; EI: 2.2+0.4; MTT: 2.+0.4 min and MPTT: 1.7+0.4 min. Relative function for the left and right kidney was 52% and 48%+.4%, respectively. The excellent agreement was observed between the obtained values of renogram parameters and their reference values. Significant linear correlation between parameters of kidney excretion was obtained. The highest correlation was observed between NORA 20 and OE 20 (r=-0.936, p&lt; 0.01). In Conclusion, the IAEA Software gives reliable values of numerical parameters of kidney excretion. Results obtained for normal kidneys were almost identical with previously reported reference values for MAG3 parameters. Only the results for MTT and MPTT were systematically lower than the established normal values. NORA 20 highly corresponds with OE 20 and could replace the former parameter in the evaluation of kidney drainage. The preliminary results support the wide-spread use of IAEA software package in order to standardize the technique of dynamic renal scintigraphy.

533 Predictors of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction: clinical value of visually assessed renal parenchymal tracer transit time in 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renography?

533 Predictors of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction: clinical value of visually assessed renal parenchymal tracer transit time in 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renography?

Long-Term Functional Outcome of Renal Units after Laparoscopic Nephron-Sparing Surgery under Cold Ischemia

Renal-artery occlusion is used to control bleeding during laparoscopic nephronsparing surgery, but there are worries about ischemic damage. We compared the functional outcomes of kidneys treated under warm and cold ischemia. Twelve patients treated with warm ischemia and 14 treated with cold ischemia had renal function investigation 3 to 6 months postoperatively. Four and ten patients, respectively, also had preoperative studies. In patients treated with warm ischemia, two kidneys had evidence of possible damage, but the kidney with the longest ischemia (56 minutes) was normal. Among patients treated with cold ischemia, function was lost in one case. Parenchymal transit time was prolonged in five patients, but in four cases, this probably was attributable to performance of a contrast-enhanced CT scan the same day. In the fifth patient, an ischemic injury is possible. The parenchymal transit time is a good indicator of ischemic damage. Nephron-sparing surgery can lead to damage even if the ischemia time is short and cold ischemia is used. More data are needed on the factors determining such injury.

99mTechnetium-Mercaptoacetyltriglycine Scintigraphy With Full Bladder in Patients With Severe Bladder Dysfunction

We evaluated 99mtechnetium-mercaptoacetyltriglycine scintigraphy for detecting threshold bladder volume at which upper tract obstruction occurs in patients with bladder dysfunction. A total of 24 patients 19 to 74 years old with severe bladder dysfunction who underwent 99mtechnetium-mercaptoacetyltriglycine scintigraphy and videocystometrogram in a 4-year period were selected for retrospective study. 99mTechnetium-mercaptoacetyltriglycine scintigraphy was done with a full bladder with a mean instilled volume of more than 850 ml saline. In patients in whom an obstructed renal outflow pattern was observed saline was drained at a rate of 100 ml every 5 minutes while dynamic imaging was performed. If results were abnormal, the study was repeated with an empty bladder. Differential function, parenchymal transit time index and outflow efficiency were calculated. Of the 24 patients 15 had an obstructed outflow pattern with a full bladder, which was relieved at a bladder volume of less than 390 ml (median 300, range 250 to 600). Only 2 of these 15 patients had a normal vesical end filling pressure of less than 20 cm H2O. There was no obstruction in 9 patients, of whom 5 had increased vesical end filling pressures. Followup in patients who had normal tracer outflow on a full bladder showed no decrease in renal function, while a small decrease was seen in patients who had obstructed outflow on a full bladder. This novel, full bladder 99mtechnetium-mercaptoacetyltriglycine scintigraphic technique provides the ability to detect bladder volumes at which obstructive outflow patterns develop in patients with severe bladder dysfunction.

Nephron-Sparing Surgery for Renal Tumours: Acceleration and Facilitation of the Laparoscopic Technique

ObjectivePresent our surgical technique for and experience with laparoscopic partial nephrectomy (LPN) for renal tumours during warm ischaemia. MethodsTwenty-five patients underwent LPN during warm ischaemia via a transperitoneal four-trocar approach. Mean tumour size was 26.2±7.3mm (range: 11–39mm). Sixteen tumours were exophytic, 7 endophytic, and 2 central. The renal vessels were secured by an umbilical tape and occluded by a self-made Rumel tourniquet. Tumours were excised with a cold Endo-shear. The interstitial tissue and collecting system was closed using a running suture secured by two resorbable clips. Parenchymal edges were approximated using a running suture over a haemostatic bolster. The threads were secured by non-resorbable clips. During follow-up, renal function was evaluated by determination of serum creatinine, 99mTc-mercaptoacetyltriglycine scintigraphy, and parenchymal transit time. ResultsMean ischaemia time was 28.9±5.2min (range: 19–40min) and the mean blood loss was 177.4±285.5ml (range: 50–1500ml). No intraoperative complications occurred and no patient needed conversion to open surgery. Surgical margins were negative in all patients. One postoperative surgical-related perirenal haematoma occurred, which was treated conservatively (no transfusions required). None of the patients had a urinary leak. During a mean follow-up of 6.2 mo (range: 1–15 mo), none of the patients had local or port-site recurrence or distant metastasis. Parenchymal transit time was increased in 1 of 10 investigated patients (ischaemia time: 26min), indicating ischaemic parenchymal damage. ConclusionOur technical refinements for LPN during warm ischaemia have widened indications to more complex tumours. The use of clips rather than knot tying made the procedure easier and faster and allowed completion of the suturing during an acceptable warm ischaemia time. The self-made Rumel tourniquet is safe and efficient for vessel control and occlusion. These improvements increase feasibility so that LPN can be used by more laparoscopic urologic surgeons.

58: Does Warm Ischemia Time During Laparoscopic Surgery Detoriate Renal Function?-Results of Parenchymal Transit Time Measurement

You have accessJournal of UrologyModerated Poster, Saturday, May 20, 2006, 1:00 - 3:00 pm1 Apr 200658: Does Warm Ischemia Time During Laparoscopic Surgery Detoriate Renal Function?-Results of Parenchymal Transit Time Measurement Axel Haecker, N. Albquami, S. Jeschke, J. Ziegerhofer, S. Prammer, K. Leeb, and Gunter Janetschek Axel HaeckerAxel Haecker More articles by this author , N. AlbquamiN. Albquami More articles by this author , S. JeschkeS. Jeschke More articles by this author , J. ZiegerhoferJ. Ziegerhofer More articles by this author , S. PrammerS. Prammer More articles by this author , K. LeebK. Leeb More articles by this author , and Gunter JanetschekGunter Janetschek More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(18)32325-5AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "58: Does Warm Ischemia Time During Laparoscopic Surgery Detoriate Renal Function?-Results of Parenchymal Transit Time Measurement." The Journal of Urology, 175(4S), p. 20 © 2016 by American Urological AssociationFiguresReferencesRelatedDetails Volume 175Issue 4SApril 2006Page: 20 Advertisement Copyright & Permissions© 2016 by American Urological AssociationMetricsAuthor Information Axel Haecker More articles by this author N. Albquami More articles by this author S. Jeschke More articles by this author J. Ziegerhofer More articles by this author S. Prammer More articles by this author K. Leeb More articles by this author Gunter Janetschek More articles by this author Expand All Advertisement PDF downloadLoading ...

Diagnosis of kidney transplant obstruction using Mag3 diuretic renography.

Kidney transplant obstruction (KTO) following renal transplantation remains an important reversible cause of allograft dysfunction, requiring prompt diagnosis to prevent long-term graft damage. Although ultrasound can accurately diagnose renal transplant hydronephrosis, it cannot be used to assess its functional significance. We prospectively assessed the utility of technetium-99m mercaptoacetyltriglycine (Tc99m MAG3) diuretic renography for the diagnosis of allograft KTO, using standard visual and quantitative parameters, as well as calculated renal output efficiency (OE), which has been postulated to improve diagnostic yield. From a cohort of 45 renal transplant patients, two subgroups were formed. The first group of transplant recipients (n = 21) with stable function and no obstruction was used to derive normal values for Tc99m MAG3 scans. A second group of transplant recipients with acute renal dysfunction in whom KTO was clinically suspected was used to test the diagnostic utility of these derived values (n = 43 scans). KTO was diagnosed independently of the MAG3 scans by a fall in the serum creatinine in response to renal pelvis urinary drainage. OE in 12 renal allografts with KTO was significantly reduced compared with 31 Tc99m MAG3 scans without KTO (59.6 +/- 18.9 vs. 81.6 +/- 5.4%, p < 0.001). In KTO, the mean time of isotope appearance in the bladder (time to bladder [TTB]) was extended compared with unobstructed allografts (7.9 +/- 4.1 vs. 3.6 +/- 1.5 min, p < 0.001). Measurement of OE significantly improved the accuracy of diuretic MAG3 renography in the diagnosis of renal allograft KTO, especially when supplemented by the TTB, parenchymal transit time and shape of the renogram curve. Ureteric obstruction of the kidney transplant can be diagnosed with an OE reduced to < 75% (sensitivity 92%, specificity 87%) and confirmed by isotope hold-up in the pelvicalyceal system. A normal or slowly declining renogram curve effectively excluded KTO (sensitivity of 96%, negative predictive value of 84%). A parenchymal transit time of > 5 min and a TTB of > 7 min both yielded a sensitvity of 92% and a specificity of 81%. In conclusion, MAG3 renography is a clinically useful investigation for the diagnosis of KTO.

Endoluminal repair of abdominal aortic aneurysm causes more perioperative renal dysfunction than open repair

Abstract Background In this prospective case–control study the aim was to compare perioperative renal function in well matched patients undergoing open repair (OR) (group 1) or endoluminal repair (ER) (group 2) of an abdominal aortic aneurysm (AAA) and preoperative renal function in other patients undergoing ER (group 3) with function 1–3 years after surgery. Methods Of 73 patients undergoing AAA repair, 45 were recruited to the study as follows: 14 patients (median age 77 years, 12 men) to group 1, 14 patients (median age 76 years, 11 men) to group 2 and 17 patients (median age 76 years, 14 men) to group 3. Serum creatinine, creatinine clearance and/or glomerular filtration rate (GFR) were measured coupled with 99mTc-radiolabelled mercaptoacetyltriglycine (MAG3) renal studies. From the MAG3 renal scans, perfusion, split renal function, mean parenchymal transit time (MPTTI) and outflow pattern were assessed. Groups 1 and 2 underwent scintigraphic evaluation before, and 8 days after operation. Group 3 was assessed before operation and 1–3 years later. Results Fifteen of 31 patients undergoing ER had preoperative renal dysfunction (GFR less than 50 ml min−1) compared with two of 14 who had OR. Ten patients from groups 2 and 3 developed severe renal dysfunction. Of these, two died, one required haemodialysis (graft deployed over the renals), two were dialysis-free but developed worsening renal function and five regained their previous renal function. In four patients who had ER, differential function improved, in one with retroperitoneal fibrosis it deteriorated and in nine it was unchanged. See Table below. Conclusion ER is associated with a greater degree of perioperative renal dysfunction than OR. In the absence of technical problems with endograft deployment, renal function in ER in the long term is not adversely affected.

Improved automatic separation of renal parenchyma and pelvis in dynamic renal scintigraphy using fuzzy regions of interest

The aim of the study was to examine the physiological relevance of factors produced by a modified procedure for factor analysis of dynamic renal studies. Factor analysis has been applied locally to subsets of dynamic renal data which were well defined in both space and time domains. Optimised factor images resulting from different subsets were used as fuzzy regions of interest (ROIs) for the extraction of time-activity curves corresponding to renal parenchyma, renal pelvis, vascular and spatially homogeneous background. The original procedure employed the factor images of renal parenchyma and pelvis resulting from an analysis of the interval between the peaks of parenchymal and pelvic curves. In an attempt to improve the separation of renal parenchyma and pelvis, new fuzzy ROIs were used. They correspond to the factor image of renal uptake obtained from the analysis of the early phase of the study, and to the factor image of the renal pelvis obtained from the outflow phase. The curves generated with the new fuzzy ROIs were compared with those of the original procedure and tested for the presence of known artefacts inconsistent with the expected physiological behaviour. Unlike with the original procedure, no such artefacts were found. The most striking difference was that the pelvic factor curves did not start from zero time of the study but exhibited a physiologically correct initial horizontal zero segment the length of which correlated closely with the minimum parenchymal transit time (r=0.79, n=46, P<0.001). The new method permits easy and reliable application of factor analysis to dynamic renal studies. Problems which remain to be solved are user-independent identification of the optimum factors and suboptimal performance of the method under extreme conditions. Our results provide additional evidence that factor analysis can extract physiologically relevant information quantitatively from dynamic scintigraphic data.

Tc-99m DTPA renal scintigraphy using deconvolution analysis with six functional images of the mean time to evaluate acute pyelonephritis.

In 38 children with proved P-fimbriated Escherichia coli acute pyelonephritis, Tc-99m DTPA dynamic renal scintigraphy in the zoom mode using deconvolution analysis was performed, and the results were compared with those of Tc-99m DMSA scans. From the dynamic study, six functional images of the mean time were generated. Each functional image was analyzed separately to search for focal areas of increased mean time within the kidney contour, especially over the kidney parenchyma. Time-activity curves from these areas were generated and analyzed. Tc-99m DMSA scintigraphy showed generalized or focal decreased uptake in 32 (41.8%) kidneys, and deconvolution analysis of Tc-99m DTPA scintigraphy revealed pathologic renographic curves in 58 (77.6%) kidneys. Prolonged whole-kidney and normal renal parenchymal transit times (dilatation without obstruction) were found in 38 (50%) kidneys, whereas prolonged whole-kidney and renal parenchymal transit times (dilatation with obstruction) were observed in 20 (27.6%) kidneys. Separate analysis of each of the six functional images of the mean time showed focal areas of increased mean time in the kidney parenchyma of 11 kidneys. In five cases, time-activity curves from these areas showed a sharp increase of activity on the descending part of the curve, which might reflect the return of urine from the collecting system into kidney cortex (i.e., intrarenal reflux). These results showed that in a urinary tract with acute pyelonephritis, urodynamic changes may lead to obstructive nephropathy and intrarenal reflux. Tc-99m DTPA renal scintigraphy in the zoom mode using deconvolution analysis with six functional images of the mean time has proved to be a valuable method to evaluate acute pyelonephritis, thus allowing dynamic and morphologic analysis of the urinary tract at the same time.

PYELOLITHOTOMY IMPROVES WHILE EXTRACORPOREAL LITHOTRIPSY IMPAIRS KIDNEY FUNCTION

Extracorporeal shock wave lithotripsy (ESWL) causes acute depression of kidney function, which chronically returns to baseline levels. This sequala could indicate chronic regression of acute lesions or a balance between lesions and relief of obstruction. We compared changes in kidney function 1 week and 3 months after ESWL and pyelolithotomy. A group of 17 women and 13 men 28 to 71 years old with 0.6 to 3 cm. stones received 1,800 to 3,200 shock waves by an electromagnetic lithotriptor. Another group of 21 women and 9 men 35 to 76 years old with 2.5 to 3.8 cm. stones underwent Gil-Vernet intra-sinus pyelolithotomy. Split renal plasma flow, glomerular filtration rate and mean parenchymal transit times of nonreabsorbable filtrate solutes were measured by dual gamma camera renography, and plasma clearances of 99mtechnetium diethylenetriaminepentaacetic acid and 131orthoiodohippurate acid. ESWL caused acute deterioration and chronic restoration of baseline parameters of the treated kidney, and small but sometimes irreversible damage to plasma flow to the untreated kidney, especially in obese patients. In contrast, pyelolithotomy acutely and chronically improved function of the treated kidney, and normalized parenchymal transit times of radiotracers. ESWL does not achieve substantial improvements in kidney function, which can be achieved by other methods of stone removal.

Relative renal uptake and transit time measurements using functional factor images and fuzzy regions of interest

The aim of the study was a quantitative comparison of relative renal uptake and both the whole-kidney and the parenchymal transit time derived from factor analysis of image sequences and provided by standard clinical procedues. In order to extract the stable, well-interpretable factors, factor analysis was performed locally in the problem-specific time and spatial windows and the resulting factor images either evaluated directly as functional images or used as fuzzy regions of interest (ROIs) for the subsequent extraction of time-activity curves from the analysed data. The values of relative renal uptake of the left kidney measured in the functional factor images, which demonstrate the initial accumulation of activity in renal parenchyma (mean 51.0%), did not differ significantly from the values obtained by a standard method (mean 51.5%, r = 0.98, P<0.001). Whole-kidney transit time calculated using fuzzy ROI curves correlated well with the reference values (r = 0.84, P<0.001); however, both its mean value (336.5 s) and the standard deviation (151.5 s) were substantially greater than those of the values provided by a standard procedure (262.8+/-86.9 s). Parenchymal transit time calculated using ROI curves correlated better with the transit time through a wider corticomedullary region rather than through a narrow cortical region, which is decisive in a differential diagnosis of renal disorders. In general, values of transit times provided by factor analysis correlated well with those provided by reference methods but with a shift towards the higher numerical values. This may have been a consequence of a greater extent of the automatically extracted fuzzy ROIs, or of occasionally delayed accumulation in the upper calyces. Results of the study provide quantitative evidence that the factor analysis of dynamic data, even without the introduction of prior physiological information, may yield clinically relevant information. However, some basic requirements, such as sufficiently high sampling frequency and count rate, adaption of the method to a specific clinical task, and proper selection of time and spatial windows for locally performed analysis, have to be fullfilled if the method is to be successfully applied clinically.

Steady-state captopril renography: continuous monitoring of the captopril-induced increase in 99m Tc-MAG 3 mean parenchymal transit time in renovascular hypertension

Steady-state captopril renography: continuous monitoring of the captopril-induced increase in 99m Tc-MAG 3 mean parenchymal transit time in renovascular hypertension

99Tcm-N,N-ethylenedicysteine scintigraphy in children with various renal disorders

We evaluated the clinical usefulness of 99Tcm-N,N-ethylenedicysteine (99Tcm-EC), a new renal tubular agent, in normal children and in children with various renal disorders and compared it with 99Tcm-mercaptoacetyltriglycine (99Tcm-MAG3). In a first group of children (Group 1), which included 15 patients and 4 normal children, both 99Tcm-EC and 99Tcm-MAG3 renal scintigraphy were performed within a period of 1-5 days. In a second group (Group 2), consisting of 12 patients, only 99Tcm-EC scintigraphy was performed. In the normal children, renograms, differential renal function (DRF) ratios and semi-quantitative parameters of the two agents were similar. For 99Tcm-EC and 99Tcm-MAG3, the mean (+/- S.D.) time to peak activity (Tmax) values were 3.2 +/- 0.5 and 3.1 +/- 0.4 min respectively, and the mean time from peak activity to 50% activity (T1/2) values were 6.3 +/- 0.5 and 6.4 +/- 0.4 min respectively. The mean parenchymal transit time index (PTTI) and mean whole-kidney transit time index (WKTTI) for 99Tcm-EC were 1.7 +/- 0.3 and 2.8 +/- 0.4 respectively, and for 99Tcm-MAG3 they were 1.8 +/- 0.2 and 3.0 +/- 0.3 min respectively. There were also no significant differences between these parameters for the two agents in children with various renal disorders, and the correlation coefficients (r) for DRF, Tmax, T1/2, PTTI and WKTTI were 0.99, 0.98, 0.94, 0.77 and 0.63 respectively. We conclude that 99Tcm-EC has excellent imaging characteristics in children, and even has some advantages over 99Tcm-MAG3. We suggest this agent can be used routinely with children.

Regional cerebral hypoperfusion in long-term Type 1 (insulin-dependent) diabetic patients

Captopril renography was utilized to assess the presence of angiotensin II dependent renovascular dysfunction in (1) 28 patients with mild to moderate essential hypertension (EH) with unimpaired renal function, and (2) 25 hypertensive patients with diabetic nephropathy (HDN). These studies were classified according to the diagnostic criteria outlined by the Working Party on Diagnostic Criteria of Renovascular Hypertension with Captopril Renography and the mean parenchymal transit time (MPTT) was used as an index for detecting the presence of angiotensin II dependent renal haemodynamic change. Patients with EH showed non-significant or non-specific alterations in the MPTT. Four patients in the HDN group showed a significant prolongation of MPTT in the presence of renin-angiotensin-aldosterone activation due to renal artery stenosis, and the other patients in this group showed a significant decrease in MPTT after captopril, consistent with increased blood flow and improved tubular transport function in the presence of microangiopathy only. We conclude that addition of MPTT to the standard diagnostic criteria of captopril renography may be helpful in predicting the beneficial or detrimental impact of angiotensin II inhibition treatment in HDN and in limiting the test protocol in EH to one post-captopril study.