International Scientific Committee of Radionuclides in Nephrourology (ISCORN) consensus on renal transit time measurements.

This report is the conclusion of the international consensus committee on renal transit time (subcommittee of the International Scientific Committee of Radionuclides in Nephrourology) and provides recommendations on measurement, normal values, and analysis of clinical utility. Transit time is the time that a tracer remains within the kidney or within a part of the kidney (eg, parenchymal transit time). It can be obtained from a dynamic renogram and a vascular input acquired in standardized conditions by a deconvolution process. Alternatively to transit time measurement, simpler indices were proposed, such as time of maximum, normalized residual activity or renal output efficiency. Transit time has been mainly used in urinary obstruction, renal artery stenosis, or renovascular hypertension and renal transplant. Despite a large amount of published data on obstruction, only the value of normal transit is established. The value of delayed transit remains controversial, probably due to lack of a gold standard for obstruction. Transit time measurements are useful to diagnose renovascular hypertension, as are some of the simpler indices. The committee recommends further collaborative trials.

The management of differentiated thyroid cancer using 123I for imaging to assess the need for 131I therapy.

BACKGROUND: Follow-up of 131I whole-body scanning after 131I ablation is associated with potential stunning. Previous studies have suggested that, for scanning, 123I is more sensitive than 131I in identifying thyroid tissue, but its specificity when positive is less certain. AIM: The use of 123I as an imaging agent in place of serial 131I imaging has been evaluated in the surveillance and treatment of differentiated thyroid carcinoma. RESULTS: A total of 186 studies in 136 patients with differentiated thyroid carcinoma were evaluated after total or near total thyroidectomy followed by 131I ablation. In 125 studies 123I scanning was negative and no 131I therapy was given; four patients were positive on 123I scanning but for other reasons no 131I therapy was given. In 48/49 patients a positive 123I scan was followed by positive 131I therapeutic uptake. Only one patient failed to show positive uptake of I when first treated and she subsequently demonstrated uptake on a second therapy. CONCLUSION: High-dose 123I imaging is the correct predictor of the 131I post-therapy scan findings in most cases, at an administered activity that avoids stunning. As a diagnostic agent it is preferable to 131I in differentiated thyroid carcinoma.

Elimination of the influence of total renal function on renal output efficiency and normalized residual activity.

UNLABELLED: One of the potential limitations in the usefulness of both renal output efficiency (ROE) and normalized residual activity (NORA) is their residual dependence on total renal function. The purpose of this study was to present and examine a new quantitative method whereby the effects of this dependence may be removed. METHODS: The analytic method involves the determination of a retention function using an unconstrained matrix algorithm deconvolution technique followed by reconvolution with a chosen standard input function to yield a new secondary renal activity time (A/T) curve from which normalized values of ROE and NORA, denoted as N_ROE and N_NORA, respectively, can then be obtained using conventional definitions. The method has been applied in a series of 50 patient studies, which had been acquired using (99m)Tc-mercaptoacetyltriglycine (99(m)Tc-MAG3) and a standard F+18 furosemide protocol, with values of the ratio of plasma clearance to plasma volume (C/V) in the range 0.013-0.242 min(-1). RESULTS: Pre- and postnormalization values of NORA, calculated at 30 min after injection, showed a significant difference in mean values (paired t test; P < 0.001), with a maximum observed difference, DeltaNORA(30), of -4.82 (-482%) and with a SD on the paired differences, DeltaNORA(30), of 0.56 (56%) or 0.63 (63%) if background subtraction on the input function (BSIF) had been performed. In contrast, corresponding values of ROE showed a nonsignificant difference in means (P > 0.05) and a SD on the paired differences, DeltaROE(30), of 3.7% or 3.2% with and without BSIF, respectively. The normalized parameters N_ROE and N_NORA were found to be strongly linearly correlated (r = -0.99; P < 0.001), in agreement with theoretical predictions. CONCLUSION: These results suggest that renal function affects NORA significantly more than ROE. The effects can be corrected by our normalization technique, resulting in equivalent values of normalized ROE and normalized NORA.

Left ventricular function assessed by gated spet after an exercise-augmented adenosine infusion. Correlation with myocardial ischaemia.

BACKGROUND: Gated single photon emission tomography (SPET) may simultaneously assess perfusion and function of the myocardium. AIM: To evaluate the relationship between the presence of ischaemia during an adenosine stress test and the changes in left ventricular (LV) function obtained after stress and at rest with gated SPET by using adenosine same-day stress and rest protocol. METHODS: The study population consisted of twenty eight patients. The gated SPET acquisition was performed both after adenosine vasodilatation and at rest with a protocol as follows: 300 MBq of Tc-99m Myoview at stress, 700 MBq reinjection at rest and double head gamma camera. Global left ventricular ejection fraction (LVEF) and end-diastolic and end-systolic volumes (EDV, ESV) as well as the regional wall motion reversibility from post-stress and resting scan were analysed. RESULTS: Wall motion disturbances were present in the stress study in 15 patients with subsequent improvement in 14 cases on the rest scans. An independent evaluation of the perfusion data revealed significant reversible myocardial ischaemia in 18 patients and negative result in 10. There was a significant difference between EDV change in patients with or without ischaemia (p<0.02). The post-stress LVEF and ESV were significantly different from those measured at rest. Reversible regional wall motion impairment indicated the presence of significant reversible myocardial ischaemia with an 88% positive predictive value (70% and 75% for sensitivity and specificity, respectively). CONCLUSIONS: The post-stress LVEF with gated SPET may not reflect true resting measurements. The qualitative assessment of regional wall motion reversibility shows better correlation with the ischaemic scan pattern than the difference in the LVEF and may be helpful in assessing the significance of reversible myocardial ischaemia.

The comparison of two gated SPET protocols: adenosine Tc-99m tetrofosmin and treadmill exercise Tc-99m MIBI.

BACKGROUND: The effect of adenosine and exercise on gated SPET left ventricular ejection fraction (LVEF), end diastolic volume (EDV) and end systolic volume (ESV) has not been fully investigated. The aim of the study was to compare functional measurements obtained in one-day adenosine rest and two-day stress-rest protocols in relation to ischaemia. MATERIAL AND METHODS: Out of 226 consecutive patients examined with submaximal treadmill stress-rest 700 MBq Tc-99m MIBI, 26 were chosen to match those subjected to adenosine (140 micro g/kg/min) enhanced by a low level exercise protocol (300 MBq and 700 MBq Tc-99m tetrofosmin for stress and rest respectively). All images were acquired on a double head system and were gated using 8 frames, 25 s per frame. RESULTS: ED and ES volumes increased after adenosine but decreased after treadmill resulting in the post-stress LVEF being significantly greater than after adenosine, 60 +/- 11 v. 51 +/- 13% (p < 0.01). This was caused by the smaller post-stress ESV in the treadmill group 40 +/- 20 v. 51 +/- 34, p < 0.05. In non-ischaemic scans the LVEF was greater (61 +/- 8 v. 51 +/- 14, p < 0.01) and EDV and ESV smaller after both stress and rest. CONCLUSIONS: The adenosine test may have an opposite influence on the EDV and ESV in comparison to the submaximal treadmill test and therefore the left ventricular function measurements after adenosine infusion should be interpreted carefully and may not represent those acquired after physical exercise. In the gated SPET scans showing ischaemia the post-stress EDV and ESV may be greater and the LVEF lower than at rest.

[Clinical outcome of patients after transmyocardial laser revascularization alone and combined with coronary artery bypass grafting]. / Kliniczna ocena efektu przezsercowej rewaskularyzacji laserowej polaczonej lub niepolaczonej z pomostowaniem aortalno-wiencowym.

The aim of the study was to assess the effect of transmyocardial laser revascularization (TMLR) alone and in combination with coronary artery bypass grafting (CABG) on the angina score (CCS--Canadian Cardiovascular Society class), exercise tolerance and left ventricular function 6 months after the procedures. Sixty two patients were subjected to revascularization, 38 to sole TMLR procedure and 24 to combination CABG and TMLR (CABG/TMLR group). The angina score and exercise stress test together with radionuclide ventriculography were performed before and 6 months after the operation. The angina class and exercise tolerance were similar in both groups preoperatively. After the operation the improvement was seen in both groups with no statistical difference. The left ventricular ejection fraction were 61 +/- 8% and 54 +/- 8% (p < 0.05) before operation and after 6 months respectively. Transmyocardial laser revascularisation alone and in combination with coronary artery bypass grafting may relieve the angina and improve the exercise tolerance. However the left ventricular ejection fraction may drop significantly.

The prospective clinical and scintigraphic assessment of patients with preserved left ventricular systolic function after transmyocardial laser revascularisation.

AIM: To analyse the clinical outcome and myocardial perfusion and function after transmyocardial revascularisation (TMR) in patients with normal left ventricular function and multivessel coronary artery disease non-amenable for standard revascularisation. METHOD AND RESULTS: Twenty three severely symptomatic patients (CCS score median 4) with normal left ventricular systolic function but coronaries non-amenable for either PTCA or CABG were subjected to TMR. The angina score, left ventricular systolic and diastolic function in radionuclide ventriculography at rest, exercise tolerance and myocardial perfusion--Thallium-201 SPECT (adenosine stress 74 and 37 MBq under nitrate cover) were evaluated before and 3, 6, 12 months post-operatively. After an average of 40 +/- 12 (range 14-56) TMR channels angina score decreased significantly (p< 0.0001) and the exercise tolerance increased (from 6.0 +/- 4.5 to 9.1 +/- 4.6 after 6 months, p< 0.05) in 21 patients. During the follow up period two patients had a myocardial infarction and one committed suicide after 6 months. Ejection fraction dropped significantly only after 1 year post-TMR from 70 +/- 13 to 63 +/- 0.13%, p < 0.05. The overall perfusion improved initially in 14 patients with subsequent deterioration in time. The changes in segmental perfusion were not associated with the symptomatic improvement. CONCLUSION: Transmyocardial revascularisation in patients with normal ejection fraction may improve the angina class, exercise tolerance and overall but not segmental perfusion and does not show any immediate effect on left ventricular function.

Imaging with radiolabelled monoclonal antibody (MUJ591) to prostate-specific membrane antigen in staging of clinically localized prostatic carcinoma: comparison with clinical, surgical and histological staging.

OBJECTIVE: To evaluate the reliability of prostate scintigraphy using a radiolabelled antibody (MUJ591) raised against the external domain of prostate-specific membrane antigen (PSMA) in the staging of early prostate cancer. PATIENTS AND METHODS: This was a prospective study of 16 patients who had radical retropubic prostatectomies (median PSA 9.75 ng/mL). All patients underwent PSMA imaging using MUJ591 radiolabelled with (99m)Tc using a photo-reduction technique. RESULTS: The findings of prostate imaging and histology were identical in seven patients. Scans showed understaging and overstaging in six and three patients, respectively. CONCLUSIONS: PSMA scintigraphy using (99m)Tc-labelled MUJ591 identifies the presence of prostate cancer, but is not sensitive in delineating micro-invasion of the capsule, seminal vesicles or bladder neck. As in other studies it seems to be useful in detecting prostate bed recurrence and distant micrometastasis.

Infection imaging with radiopharmaceuticals in the 21st century

Infection continues to be a major cause of morbidity and mortality worldwide. Nuclear medicine has an important role in aiding the diagnosis of particularly deep-seated infections such as abscesses, osteomyelitis, septic arthritis, endocarditis, and infections of prosthetic devices. Established techniques such as radiolabelled leucocytes are sensitive and specific for inflammation but do not distinguish between infective and non-infective inflammation. The challenge for Nuclear medicine in infection imaging in the 21st century is to build on the recent trend towards the development of more infection specific radiopharmaceuticals, such as radiolabelled anti-infectives (e.g. 99mTc- ciprofloxacin). In addition to aiding early diagnosis of infection, through serial imaging these agents might prove very useful in monitoring the response to and determining the optimum duration of anti-infective therapy. This article reviews the current approach to infection imaging with radiopharmaceuticals and the future direction it might take