Inter-observer reproducibility of relative 99Tcm-DMSA uptake.

99Tcm-DMSA planar images of 49 randomly selected patients (10 adults, 39 children) were sent to 15 physicians at various centres in Belgium. They were asked to calculate, using their own routine program, the relative uptake (expressed as a percentage) of each kidney. The data were sent on disks formatted so that they could be read by all participants, using their own computer systems. For each scan, the inter-observer variability was expressed using the maximum difference and the standard deviation of left renal uptake. Left renal uptake measured by the 15 observers in the 49 patients was 29.0-72.0% (mean +/- s = 49.8 +/- 6.4%). The maximum differences in left renal uptake ranged between 1.7% and 12.0% (4.5 +/- 2.6%); however, the maximum difference did not exceed 8% in about 90% of the patients. The standard deviations of the individual left renal uptake were between 0.6 and 3.9 (1.3 +/- 0.8). The standard deviations were significantly higher in adults (mean standard deviation = 2.05) than in children (mean standard deviation = 1.12) (P < 0.001); this was probably related to the high background observed in three adults with severe renal impairment. Indeed there was a significant correlation (P < 0.001) between the standard deviation and both the signal-to-noise ratio and the degree of asymmetry between the right and left kidneys. The differences between right and left kidney uptake were systematically lower for some observers, suggesting an influence of the calculation programs.

A multicenter trial on interobserver reproducibility in reporting on 99mTc-DMSA planar scintigraphy: a Belgian survey.

UNLABELLED: Conflicting opinions have been expressed regarding reproducibility in 99mTc-dimercaptosuccinic acid (DMSA) planar renal image interpretation. The purpose of this investigation was to determine the level of interobserver variability among a large group of Belgian nuclear medicine physicians who evaluated a randomly selected series of DMSA planar scintigraphic examinations performed on children and adults. METHODS: All Belgian nuclear medicine centers (n = 82) were invited to participate in a reproducibility study on 99mTc-DMSA scintigraphy. 99mTc-DMSA scans obtained on 10 adults and 40 children were randomly selected from the databases of 2 hospitals. Those participating in this investigation (65 centers = 79%) received a series of computer disks containing 50 99mTc-DMSA studies. To avoid potential problems related to unfamiliar display, the disks were formatted to be interpretable using the participants' own computer systems. Each participant was then free to use his or her usual display (hard copies, contrast enhancement, color scale, gray scale, and so forth). For each kidney, the observers had to choose between the following answers: normal, abnormal, equivocal, and lack of quality. RESULTS: Forty-two responses were obtained from a wide variety of institutions and from observers with different levels of experience in interpreting 99mTc-DMSA scintigraphy. Altogether, the following data were obtained: 60.8% normal, 25.2% abnormal, 7.0% equivocal, and 3.2% lack of quality. The median percentage of agreement (overall reproducibility) for the 42 observers was 92%. When the results of all 42 observers were compared, the median agreements on normality and abnormality were 93.5% and 90.5%, respectively. In a small number (n = 4) of kidneys, reproducibility was poor and ranged from 51% to 70%. Except for 2 outliers, all observers had almost the same level of performance. CONCLUSION: A large number of Belgian nuclear medicine physicians participated in evaluating a large randomly selected sample of 99mTc-DMSA studies, and excellent interobserver agreement was found.

[Autonomous thyroid adenoma. Value of thallium scintigraphy and pathology]. / Adénome thyroïdien autonome. Apport de la scintigraphie au thallium et de l'histologie.

Clinical, biological, scintigraphic (99mTc, 123I, 201Tl) and histological data were reviewed in 90 patients operated for autonomous adenomas (hot nodules). Analysis of the data gave the following results: 74.4% of the nodules were solitary and 25.6% occurred in a multinodular goiter (MNG). Hyperthyroidism (FT3-, FT4-, TSH < 0.1) was present in 44% of solitary nodules and in 15% of MNG. 16.6% of patients were euthyroid, and 22.2% had a TSH < 0.1 and normal free hormones. The 201 Tl scintigraphy, performed instead of the administration of exogenous TSH, showed and uptake of Tl in the remainder of the thyroid. Four types of 201Tl uptake were observed in the pathological lobe: type 1: homogeneous uptake: type 2: heterogeneous uptake and hyperfixation in the nodule; type 3: faint uptake and hypofixation in the nodule; type 4: faint and very heterogeneous uptake. Histological analysis of the nodules showed 32.2% of follicular adenomas, 25.6% of MNG and 42.2% of colloid nodules. Among these lesions, 70% showed histological signs of hypermetabolism (resorption vesicles ...). Multivariate analysis of these data clearly demonstrates the need to redefine the clinical, biological, scintigraphic and histological concepts of autonomous adenomas. On the other hand, 91.6% of follicular adenomas show a type 2 Thallium uptake (22/24). On basis of these results, we prefer to operate these patients rather than to treat them by 131I or by percutaneous injection of ethanol.