Mean Parenchymal Transit Time Research Articles

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< 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.

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.

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.

Predictive value of captopril transit renography in essential hypertension and diabetic nephropathy

Summary 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). The 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.

Clinical Evaluation of <sup>99m</sup>Tc Diaminocyclohexane, a Renal Tubular Agent with Cationic Transport: Results in Healthy Human Volunteers

As alternatives to anionically transported hippuran, structure distribution experiments on a series of 99mTc-labelled primary substituted ethylene diamine compounds led to selection of 99mTc diaminocyclohexane (DACH) for clinical evaluation, 99mTc DACH, a cation with the structure trans-[O2(DACH)2 99mTc]+ is prepared by mixing 50 mumol DACH, 1 mumol stannous tartrate and 500 MBq of 99mTc. Seven normal volunteers underwent renal imaging and clearance studies using 150 MBq of 99mTc DACH and 1 MBq of 125I hippuran simultaneously. The images with 99mTc DACH revealed good uptake and excretion. The mean +/- 2 SD values of parenchymal and whole-kidney transit time indices and mean parenchymal transit time were 46 +/- 33, 75 +/- 64 and 141 +/- 51 s, respectively, similar to mercaptoacetyl triglycine. The mean clearance of 99mTc DACH was found to be 163 ml/min (SD = 32). Following cationic blockade with 900 mg oral thiamine, significant reduction (p < 0.001) in DACH clearance was noted, but hippuran clearance remained unaltered. The results support the hypothesis that 99mTc DACH is transported cationically.

Quantitative static and dynamic renal scintigraphy with diuresis stimulation in renovascular hypertension.

The results of computer-assisted static and dynamic renal scintigraphy in 57 patients with renovascular hypertension (RVH) and 23 patients with essential hypertension (EH) are presented. The following parameters were quantified: renal size (RS), count density (CD), relative unilateral renal clearance (RRC), mean parenchymal transit time (PTT), difference of time-to-peak of activity (tmaxd) to stenosed minus non-stenosed side, effect of frusemide (FE) and renal parenchymal radionuclide retention (RI). Among 57 stenosed renal arteries we detected 54 (true-positive cases) and missed three (false-negative cases); among 23 patients with EH and no significant haemodynamic renal artery stenosis, we found 21 cases correctly negative and two patients falsely positive. These data yielded a sensitivity of 95% and a specificity of 92%. The quantification of renal radionuclide studies in renal artery stenoses minimizes false-positive results and increases their specificity. This study shows that, because of its sensitivity, quantitative renal scintigraphy reliably allows the assessment of the functional haemodynamic effects of a renovascular lesion (significant stenosis) in the diagnostic work-up and during follow-up after surgical reconstruction or percutaneous transluminal angioplasty (PTA). The evaluation of renal function is in general greatly supported by the quantitative parameters, yet particularly after medication with converting enzyme inhibitors and after intervention.