J. Bomanji

Clinical evaluation of technetium-99m infecton for the localisation of bacterial infection.

The aim of the study was to distinguish infection from inflammation in patients with suspected infection using technetium-99m Infecton. Ninety-nine patients (102 studies) referred for infection evaluation underwent imaging with 400 MBq99mTc-Infecton at 1 and 4 h. Most patients had appropriate microbiological tests and about half (56) had radiolabelled white cell scans as well. No adverse effects were noted in any patient. The clinical efficacy of99mTc-Infecton depended in part on whether imaging was undertaken during intibiotic therapy for infection or not. In consultation with the microbiologist, 5–14 days of appropriate and successful antibiotic therapy was considered adequate to classify some results as true-negatives. The figures for sensitivity and specificity of99mTc-Infecton for active or unsuccessfully treated infection were 83% and 91% respectively. It is concluded that99mTc-Infecton imaging contributed to the differential diagnosis of inflammation. It is being used as the first imaging modality when bacterial infection is suspected.

Clinical experience with 99mTc-MAG3, mercaptoacetyltriglycine, and a comparison with 99mTc-DTPA

The preparation, application and clinical usage of 99mTc-mercaptoacetyltriglycine, MAG3, a tubular secreted compound, is described in the first 225 patients in a phase III study. Image quality, relative renal function, and renal transit times were compared with a 4 fold greater administered activity of 99mTc-DTPA in 11 patients. Correlation coefficients of 0.94 for relative function, 0.83 for parenchymal transit time index and 0.82 for whole kidney transit time index were found. Frusemide responses were similar. 99mTc-MAG3 is an efficacious radiopharmaceutical for routine renal radionuclide studies, giving excellent image quality in patients with hypertension, poor renal function, obstructive nephropathy or a renal transplant.

Clinical evaluation of 99mTc 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.

Observations on the function of normal adrenomedullary tissue in patients with phaeochromocytomas and other paragangliomas

Abstract123I-MIBG is a norepinephrine analogue used for imaging phaeochromocytomas and other paragangliomas. In this study 7 normal volunteers and 31 subjects with high or borderline high plasma catecholamine and urinary metanephrine and VMA levels were investigated. In the normals the uptake by the adrenal medulla was in the range of 0.01%–0.21% of the injected dose at 22 h. In 22 subjects there was no evidence for any paraganglioma, with the uptake by the adrenal medulla in the range of 0.01%–0.22% of the injected dose at 22 h. In nine patients there was evidence of a paraganglioma on imaging which was confirmed on surgery. The uptake by the tumours was in the order of 0.001%–0.14% of the injected dose per gram of tumour tissue. In all nine cases the non-tumorous adrenal medulla could be visualized; the uptake in the adrenals was in the range of 0.01%–0.21% of the injected dose. This study shows that in the presence of elevated plasma catecholamines of tumour origin the unaffected adrenal medullary tissue retains the capacity for 123I-MIBG uptake. In the two cases also studied by adrenal venous sampling, catecholamine release was also within the normal range.

Volume-dependent intracavernous hemodilution during pharmacologically induced penile erections.

The change in the cavernous hematocrit following induction of pharmacological erection by an intracavernous injection of papaverine hydrochloride was documented in normal controls and patients with impotence. Blood samples taken from the penile cavernosa showed a significantly lower hematocrit compared to the systemic venous blood in all normal subjects. The decrease in the cavernous hematocrit was attributable to dilution of the cavernous blood pool by the injected volume of the drug, since this was not observed in erections produced by visual sexual stimulation. It appears that a restriction of the cavernous venous outflow in response to papaverine injection causes sequestration of the diluted blood in the cavernous compartment. The degree of cavernous hemodilution was found to aid in the differential diagnosis and was especially valuable in differentiating patients with arteriogenic impotence from those with venous leakage.

The effect of ramipril. A new angiotensin-converting enzyme inhibitor on cortical nephron flow and effective renal plasma flow in patients with essential hypertension

A placebo-controlled study of Ramipril on total and intrarenal flow distribution was carried out in 7 patients with essential hypertension. Cortical nephron flow was measured using radiolabelled tubular secreted radiopharmaceuticals 123I orthoidohippurate or 99mTc mercaptoacetyl triglycine by the transit time distribution technique. Both systolic and diastolic blood pressure were reduced significantly by Ramipril without significant changes in an index of cardiac output or in effective renal plasma flow. Cortical nephron flow increased from 207 +/- 7 to 257 +/- 21 ml/min (mean +/- SEM) p less than 0.05 and the percentage of flow to cortical nephrons increased by 6% (p = 0.05). Ramipril corrects the reduced cortical nephron flow found in essential hypertension.

Radionuclide Evaluation Pre- and Postextracorporeal Shock Wave Lithotripsy for Renal Calculi

Forty-two patients were evaluated pre- and postextracorporeal shock wave lithotripsy (ESWL) using [99mTc]DTPA renography. A quantitative evaluation showed that the relative renal function decreased 2-3 days post-ESWL on the treated side, and the parenchymal transit time index (PTTI) increased 2-3 days post-ESWL (p less than 0.001) on the treated side and returned to the pretreatment level by 3 wk post-ESWL. The untreated side showed an increase in PTTI 2-3 days post-ESWL (p less than 0.01), which returned to normal by 3 wk post-ESWL. A significantly greater increase in PTTI was seen in patients who received greater than 1,000 shocks as compared with those who received less than 1,000 shocks. Five patients developed obstructing uropathy post-ESWL, when stone fragments caused ureteric obstruction.