1 Serviço de Medicina Nuclear - Hospital Garcia de Orta, Faculdade de Ciências Médicas - Universidade Nova de Lisboa, Almada / Lisboa, PORTUGAL
2 Serviço de Cirurgia Pediátrica - Hospital Dona Estefânia/CHLC,Lisboa, PORTUGAL
3 Serviço de Medicina Nuclear - Hospital Garcia de Orta, Almada, PORTUGAL
4 Serviço de Pediatria - Hospital Garcia de Orta, Almada, PORTUGAL
5 Serviço de Cirurgia Pediátrica - Hospital Garcia de Orta, Almada, PORTUGAL
6 Unidade de Medicina Nuclear - Joaquim Chaves Saúde, Carnaxide,PORTUGAL
7 Unidade de Cuidados Intensivos Neonatais - Hospital Dona Estefânia/CHLC, Faculdade de Ciências Médicas - Universidade Nova de Lisboa, Lisboa, PORTUGAL
8 CHU Saint-Pierre, Brussels, BELGIUM
- EANM'14 - 27th Annual Congress of the European Association of Nuclear Medicine
Introduction: For the evaluation of renal drainage through Dynamic Renal Scintigraphy (DRS) several parameters have been described in the literature, such as: Normalized Residual Activity (NORA); Output Efficiency (OE); the time to reach a decay of 50%, either from the peak of the DRS or from the administration of a diuretic (T1/2); and the residual or post-void renal counts normalized to the maximum counts (PostVoid/Max). On a recent review paper it is mentioned that although T1/2 needs strict standardization in order to be accurate, this parameter and the PostVoid/Max should be used to interpret DRS and are more reliable if a region of interest (ROI) is restricted to retained activity in the collecting system (ROI-Coll) rather than in the whole kidney (ROI-WK).
Aim: Based on an occasional sample, we tried to do a preliminary analysis on the differences between using a Whole Kidney ROI and a Pelvic ROI, for the calculation of renal drainage parameters. Population and Methods: We analysed 26 renal units from 15 DRS performed to 10 children (4 males and 6 females; median age at the DRS of 13[96;6] months). The DRSs were performed with 99mTc-MAG3 and the activities administered according to the EANM Paediatric Dosage Card. We evaluated the differences between the results of PostVoid/Max and the time at which maximum counts were reached (TMax), using the two types of ROIs (ROI-WK and ROI-Coll). Due to the small size of the samples and its asymmetrical distribution, for statistical analysis we used the non parametric Sign Test for related samples. We also considered the observer’s confidence on ROI definition.
Results: According to the tests results, there was a statistical evidence of a difference between the use of the two ROIs for PostVoid/Max (p=0,011) but not for TMax (p=0,078). Nevertheless, observers felt that it is much more difficult to draw a ROI around the collecting cavities than around the whole kidney, and that it is notpossible to be sure that it is an exclusive collecting system ROI, especially in serious hydronephrosis; there were also some serious doubts about the background ROI, in particular if it should always be the same. Comments: Although it seems that there is a difference between drainage parameters based on the whole kidney and the collecting system, we believe there should be caution on its interpretation.