Characterization of Atypical Pheochromocytomas with Correlative MRI and Planar/Hybrid Radionuclide Imaging: A Preliminary Study

• Published in: Applied sciences 2021-10, Vol.11 (20), p.9666
• Main Authors: Galatola, Roberta, Attanasio, Ludovica, Romeo, Valeria, Mainolfi, Ciro, Klain, Michele, Simeoli, Chiara, Modica, Roberta, Guadagno, Elia, Aprea, Giovanni, Basso, Luca, Nicolai, Emanuele, Salvatore, Marco, Maurea, Simone
• Format: Article
• Language: English
• Subjects: Abdomen; atypical; Catecholamines; Computed tomography; cystic; Cysts; Degeneration; Deoxyglucose; Emission analysis; Evaluation; Hemorrhage; Histopathology; Iodine; Lesions; Magnetic resonance imaging; Medical imaging; MRI; Pheochromocytoma; Population; Positron emission; Positron emission tomography; Radioisotopes; radionuclide planar/hybrid imaging; Scanners; Scintigraphy; Tomography; Tumors
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app11209666

Pheochromocytomas may show atypical imaging findings leading to diagnostic pitfalls. We correlated the results of magnetic resonance imaging (MRI) with those of radionuclide studies in patients with pheochromocytomas. T2-weighted (-w), T1-w chemical-shift and T1-w dynamic contrast enhanced (DCE) MRI sequences were evaluated to assess tumor structure. 131Iodine metaiodobenzylguanidine (MIBG) scintigraphy, 18fluoro (F) deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) or FDG PET/MRI were evaluated for direct comparison. Of a total of 80 adrenal lesions in 73 patients, 20 in 18 patients were pheochromocytomas. More than half (55%) of the pheochromocytomas (n = 11) had the typical increased signal intensity on T2-w and T1-w DCE, while the remaining (n = 9) lesions showed atypical findings; of these nine latter atypical lesions, seven (35%) were cystic (two totally, three predominantly and two partially) and two (10%) were hemorrhagic on MRI. In these atypical lesions, MIBG scintigraphy (n = 5), FDG PET/CT (n = 6) or FDG PET/MRI (n = 2) showed inhomogeneous tracer uptake in the residual viable tissue providing tumor characterization; however, one predominantly cystic pheochromocytoma showed false negative MIBG scan. Our preliminary results show that cystic degeneration may be frequent in pheochromocytoma being so marked that only a thin rim of viable cells may residue to disclose the true nature of the tumor. MRI findings together with those of correlative planar/hybrid radionuclide images are helpful to characterize these atypical pheochromocytomas. In particular, tumor accumulation of MIBG and/or FDG is able to classify these lesions as not simple cysts; in detail, the presence of partial MIBG uptake allows the diagnosis of pheochromocytomas, while the presence of partial FDG uptake generically reflects the presence of viable solid tissue of such cystic tumors.