Which one of the following imaging modalities is most sensitive for evaluation of extra-adrenal phaeochromocytoma.
Ans- C Ref- Preferred imaging modalities Patients who may be referred for imaging of the adrenal glands include those with new or worsening diabetes mellitus (owing to impaired glucose regulation) and those with hypertensive crisis after anesthesia, surgery, or treatment with medications. Imaging may also be performed in patients with a known history of multiple endocrine problems. Computed tomography (CT) scanning and magnetic resonance imaging (MRI) have higher sensitivity in detecting pheochromocytomas than nuclear medicine scanning with iodine-131 metaiodobenzylguanidine (131I-MIBG), although 131I-MIBG uptake is more specific. Some authors prefer to use MIBG uptake scanning as the initial screening modality because it enables whole-body imaging, making it useful for the detection of extra-adrenal tumors and metastatic deposits. Once an adrenal or extra-adrenal tumor is detected, CT scanning or MRI of the region may be performed for anatomic localization prior to surgical removal. If 131I-MIBG uptake is negative but the clinical findings suggest pheochromocytoma, CT scanning or MRI of the chest or abdomen may be performed, because the false-negative rate of MIBG scintigraphy is 10%. Luster et al investigated the specificity and sensitivity of (18)F-3,4-dihydroxyphenylalanine (DOPA) positron emission tomography (PET) scanning, CT scanning, and a combination of the 2 modalities in the identification and localization of adrenal and extra-adrenal pheochromocytomas. Nineteen lesions were detected by all 3 imaging methods, but only DOPA PET/CT scanning accurately characterized and localized them all, demonstrating, on a per-patient basis, a sensitivity of 100% and a specificity of 88%. A further study by Gaertner et al concluded the (18)F-LMI1195 is a promising tracer for tumor imaging. Saad et al found in a study of 23 patients with a history of pheochromocytoma/paraganglioma that (18)F-FDG PET/CT was a superior tool for the localization of recurrent tumors. Nonenhanced computed tomography (CT) scan in a 35-year-old woman with hypertension demonstrates a large, right-sided, inhomogeneous adrenal mass (white arrows) with a central area of low attenuation that represents hemorrhage or necrosis. The upper pole of the displaced right kidney can be seen (black arrow). Courtesy of Dr Ali Shirkhoda, William Beaumont Hospital, Michigan. View Media Gallery Axial gradient-recalled magnetic resonance angiogram in a 42-year-old woman with a 5-year history of hypertension who underwent magnetic resonance angiography for the assessment of renal arterial stenosis. Although the renal arteries were unremarkable, a 7.5-cm X 5-cm right adrenal mass was incidentally identified. Angiogram demonstrates a large, right-sided, inhomogeneous adrenal mass (arrows). Courtesy of Dr Ali Shirkhoda, William Beaumont Hospital, Michigan.
MRI
CT
DOPA PET scan
MIBG scan