Quality control of 99Mo/99Tcm generators: results of a survey of the Radiopharmacy Working Group of the Italian Association of Nuclear Medicine (AIMN)

A multicentre survey of the quality control of 99Tcm generators has been completed: 245 generators from seven different commercial sources were tested over a period of 2 years. The results indicate that the mean pH of the eluates was 5.8 +/- 0.6; the aluminium contents were typically < 10 ppm; the radiochemical purity was 99.8 +/- 0.4% and the median 99Mo content was 3.8 x 10(-4) percent. The elution profiles gave a volume of 1.9 ml to obtain 50% of the total eluted activity and of 4.9 ml to obtain 95%. Other radionuclide impurities and heavy metal breakthrough were evaluated by graphite furnace absorption spectrometry and inductively coupled plasma mass spectrometry. National guidelines for the standardization of radiopharmacy procedures are currently being compiled.

Cardiac and pleuropulmonary AL amyloid imaging with technetium-99m labelled aprotinin

Antiproteases are known to be present in amyloid deposits. We evaluated the possibility of using an anti-serine protease (aprotinin) labelled with technetium-99m (TcA), usually employed as a cortical renal tracer, for the imaging of amyloid deposits. Because of the known high uptake of TcA by the kidneys, we limited our analysis to extra-abdominal amyloid localizations. We report the scintigraphic findings observed in 24 patients with light chain amyloidosis (AL) and one with a hereditary form who were known or suspected to have extra-abdominal involvement. Planar scans obtained 100min after i.v. TcA administration showed myocardial accumulation in 11 patients, pleuropulmonary accumulation in nine, pericardial accumulation in two and localization in the neck region (thyroid, salivary glands and tongue) in eight. TcA scintigraphy was negative in five patients without clinical or laboratory evidence of extra-abdominal involvement, as well as in 12 control group patients with cardiac and renal diseases. These preliminary results indicate TcA to be a low-cost, readily available radiopharmaceutical for imaging of extra-abdominal involvement in AL type amyloidosis.

Radioimmunoassisted follow-up and surgery vs traditional examinations and surgery after radical excision of colorectal cancer

The authors report their experience in the radioimmunodetection of recurrent colorectal cancer in comparison with traditional examinations. 485 patients were studied after radical surgery for colorectal cancer: 168 (Group 1) were studied with a radioimmunoassisted follow-up plan including: Immunoscintigraphy (IS), serum markers assays, Radioimmunoguided Endoscopy (RIGE), Intraoperative Radioimmuno-localization (IORIL) in case of reoperation; 317 (Group 2) underwent a protocol with traditional examinations. In 24 patients of Group 1 IS was performed even at the time of their admission for primary cancer. 7 patients underwent RIGE for primary cancer and 16 in the follow-up. IORIL was performed in 12 patients with primary cancer and in 16 in the course of reoperation. The radioimmunodiagnostic methods were performed after a single administration of the radiolabeled MAb (111In F(ab')2 a-CEA and 111In B72.3). The radioimmunoassisted follow-up plan detected a greater number of recurrences than traditional examinations (27% vs 13%). The rates of radical reoperation in Group 1 and 2 were 61% and 37% respectively. 33% of the patients of Group 2 were alive 24 months after radical reoperation vs 62.5% of the patients of Group 1. Immunoscintigraphy demonstrated a good sensitivity and specificity, mainly in the detection of pelvic recurrences (sens. 92%, spec. 84%). The radioimmunoassisted follow-up plan was well accepted by the patients. RIGE led to the detection of 3 periluminal recurrences of rectal cancer that traditional investigations failed to demonstrate and in 5 cases influenced the patients management. IORIL detected minimal tumor foci (2 mm.) where pre and intraoperative study were negative, while the histopathologic examination gave evidence of tumor. Considering that the costs of the radioimmunodiagnostic methods and of traditional examinations are very similar, we can conclude that the radioimmunoassisted follow-up plan has a favorable cost/benefit rate and a remarkable impact on the treatment of patients with colorectal cancer.

Cortical kidney scan evaluation in the follow-up of children with vesico-ureteric reflux

We present the results obtained in the follow-up of 66 children with vesico-ureteric reflux (VUR) of different grades (111 refluxing renal units, RU; the VUR being bilateral in 47 children), employing the renal cortical agent 99mTc-aprotinin (TcA). Together with the visual inspection of the scan, we adopted a quantitative approach, expressing the results as the split percent uptake of the injected dose. The detection of morphological anomalies was more frequent in the cases of more severe reflux. Scars were noted in 38 RU, with a higher prevalence in more severe grades, except for grade V where severe impairment was more frequent. With regard to the amount of functioning parenchyma, the probability of a significant loss of nephrons (expressed by a low uptake of TcA), rose with the grades, although the higher grades were not invariably associated with parenchymal failure. The abnormality detection rate is higher by about 2:1 with the TcA scan than with other diagnostic modalities such as i.v. pyelography or echography. No differences were found between RU with or without scars as regards evolution over time; only when the TcA uptake at presentation was lower than 10% was the normal development of the RU likely to be hindered. From these data it can be concluded that early diagnosis is the key factor in the management of these children with VUR; the morpho-functional assessment with TcA uptake is probably the most effective technique for the detection of parenchymal abnormalities. In addition, the test has a high prognostic value, an uptake lower than 10% indicating an unfavourable prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Radioimmunolocalization of pelvic recurrences from rectosigmoid cancer employing 111In anti-CEA F(ab')2

Thirty-two immunoscintigraphic studies have been performed in 26 patients previously operated upon for rectosigmoid cancer, for an early detection of pelvic recurrence, employing 111In anti-CEA, F(ab')2. The sensitivity was 1, specificity 0.76 and accuracy 0.84, leading to a positive predictive value of 0.69 and a negative value of 1. The combined use of a non-imaging surgical probe in 6 of the 10 patients who underwent second look surgery, detecting the 111In radioactivity used for RIS, improved diagnostic accuracy, ruling out the presence of tumors in 3 patients with false positive RIS.

The role of meta-iodo [131I]benzylguanidine (MIBG) in the diagnosis and follow-up of neuroblastoma

Fourteen scans employing the adrenergic blocking agent [131I]MIBG were performed on 10 children with neuroblastoma (NB) or ganglioneuroblastoma (GNB). The scans were negative in 5 cases, and 1 further case produced doubtful results in both the MIBG and CT scan tests. In 4 cases, very positive results were obtained with clear vision of the primary tumor and its metastases. In 1 case, which demonstrated partial differentiation of the outer part of the tumor mass toward GNB, a differentiated tumor specimen did not reveal significant uptake of the tracer. Half-lives of the tracer as measured by external detection in the period 24-48 h after injection were reduced after successful therapy. MIBG scanning appears to be a feasible indicator of NB adrenergic activity, and it can assume a primary role in the staging and follow-up of NB. Higher tumor uptake of the [131 I]MIBG and low background offer new perspectives in the radiometabolic treatment of MIBG.

Assessment of split renal function with 99mTc-aprotinin

The aim of this work is to correlate the net kidney uptake of 99mTc-aprotinin (TcA) in 103 subjects with separate effective renal plasma flow (ERPF) and some blood chemistry parameters at 90, 180, and 360 min postinjection both in the normal and diseased kidney. Correlations found with separate ERPFs are highly significant at any time (P less than 0.001). However, although the slope of the regression line is steeper at 180 min, r tends to deteriorate slightly with time postinjection and a higher intercept on the y axis; this pattern is more pronounced if diseased kidneys are considered separately. The following are probably related to the renal handling of TcA: Early scans better reflect blood flow to the kidney, while later scans are more related to the metabolism/excretion tubular mechanisms; correlations found with urea, creatinine, urea clearance, and creatinine clearance are highly significant at any time; in 20 additional patients with diseased kidneys, renal uptake measurements done 360 min postinjection first with TcA and then with DMSA showed better correlations with ERPF employing TcA. Our results indicate that TcA is a feasible indicator of split renal function even at 90 min postinjection when a scan is easily carried out on an outpatient basis.

99mTc-aprotinin: comparison with 99mTc-DMSA in normal and diseased kidneys

Aprotinin (A) and DMSA labelled with 99mTc were compared in patients with normal (NK, n = 12) and diseased kidneys (CRF, n = 13) by means of quantitative serial scans and measurements of blood clearance and urinary excretion. Serial scans only were obtained in additional 13 patients. Scan quality in the NK patients was essentially equal: faster blood clearances, reduced urinary excretions and higher fixations of A in the target compensated for the increased liver uptake. On the other hand, the scan quality in the CRF patients was definitely superior with A, allowing detection of residual functioning parenchyma also in severe kidney failure. Correlation between the net kidney uptake 6 hrs p.i. and the separate hippuran clearance rate was better with A than with DMSA, indicating the feasibility of A in evaluating relative renal function.

99mTc-Aprotinin: Comparison with 99mTc-DMSA in Normal and Diseased Kidneys

Aprotinin (A) and DMSA labelled with 99mTc were compared in patients with normal (NK, n = 12) and diseased kidneys (CRF, n = 13) by means of quantitative serial scans and measurements of blood clearance and urinary excretion. Serial scans only were obtained in additional 13 patients. Scan quality in the NK patients was essentially equal: faster blood clearances, reduced urinary excretions and higher fixations of A in the target compensated for the increased liver uptake. On the other hand, the scan quality in the CRF patients was definitely superior with A, allowing detection of residual functioning parenchyma also in severe kidney failure. Correlation between the net kidney uptake 6 hrs p.i. and the separate hippuran clearance rate was better with A than with DMSA, indicating the feasibility of A in evaluating relative renal function.