Abstract
Purpose
This study was performed to assess the feasibility, interobserver variability, sensitivity, specificity and diagnostic accuracy of raw data and postprocessed images from a low-field (0.5-T) magnetic resonance (MR) unit in evaluating vascular complications of kidney grafts.
Materials and methods
We enrolled 49 patients undergoing MR angiography (MRA) for a clinical suspicion of renal artery stenosis. The raw data, maximum intensity projections (MIP) and multiplanar reconstruction (MPR) image sets were evaluated independently. We calculated the number and degree of stenosis, and sensitivity, specificity and accuracy for MIP, MPR and raw data image sets, together with interobserver variability.
Results
Interobserver agreement was substantial. There were no differences among the MIP and MPR algorithms and raw data images for the detection of stenosis. Raw data images were more accurate in quantifying the severity of stenosis, with higher sensitivity (75% vs. 62.5%), equal specificity and higher diagnostic accuracy (75% vs. 71.43%).
Conclusions
Contrast-enhanced MRA, even with a low-field (0.5-T) unit, is a feasible, sensitive and accurate technique for the study of the renal arteries of the transplanted kidney.
Riassunto
Obiettivo
Valutare la fattibilità tecnica, la variabilità tra gli esaminatori, la specificità, la sensibilità e l’accuratezza diagnostica delle immagini partizionali e delle ricostruzioni, acquisite con un tomografo RM a basso campo (0,5 T) nelle complicanze vascolari del rene trapiantato.
Materiali e metodi
Abbiamo selezionato 49 pazienti sottoposti a tomografia RM per sospetta stenosi dell’arteria renale. Sono state valutate indipendentemente, le immagini partizionali, le proiezioni di massima intensità (MIP) e le ricostruzioni multiplanari (MPR). Abbiamo calcolato il numero e l’entità delle stenosi, la sensibilità, la specificità e l’accuratezza sia delle immagini partizionali che delle ricostruzioni, ed abbiamo valutato la concordanza tra i due radiologi che hanno esaminato ciascun caso.
Risultati
La concordanza inter-osservatore è risultata elevata. Non abbiamo riscontrato differenze nel riconoscimento della stenosi tra le ricostruzioni MIP e MPR e le immagini partizionali. Le immagini partizionali hanno dimostrato maggior affidabilità nel quantificare la severità della stenosi, con elevata sensibilità (75% vs. 62,5%), uguale specificità e maggior accuratezza diagnostica (75% vs 71,43%).
Conclusioni
L’angio-RM con contrasto iniettato con tecnica «a bolo di contrasto», per lo studio delle arterie renali dei reni trapiantati, è una metodica fattibile dal punto di vista pratico, sensibile e con un’ottima accuratezza diagnostica, anche con apparecchiatura RM a basso campo (0,5 T).
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Stecco, A., Oronzo, P., Armienti, F. et al. Contrast-bolus MR angiography of the transplanted kidney with a low-field (0.5-T) scanner: diagnostic accuracy, sensitivity and specificity of images and reconstructions in the evaluation of vascular complications. Radiol med 112, 1026–1035 (2007). https://doi.org/10.1007/s11547-007-0203-z
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DOI: https://doi.org/10.1007/s11547-007-0203-z