Clinical Significance of Quantitative 123I-MIBG SPECT/CT Analysis of Pheochromocytoma and Paraganglioma.
OBJECTIVE
This retrospective study compared the diagnostic performances of quantitative versus visual analyses of I-MIBG scintigraphy in patients with suspected pheochromocytoma and paraganglioma (PPGL).


METHODS
SPECT images were obtained 6 and/or 24 h after MIBG injection from 68 patients with clinically suspected PPGL, with attenuation correction by low-dose unenhanced CT. Planar images were also obtained at each time point. SUVs of retroperitoneal tumors, including PPGLs, and physiological uptake by normal organs were measured using the SPECT images. The diagnostic performance of the quantitative assessment in differentiating PPGLs from other lesions or normal adrenal glands was assessed using receiver operating characteristic analysis. The planar scans and 6-h and 24-h SPECT/CT images were also assessed visually.


RESULTS
PPGLs showed a significantly higher SUVmax (mean ± SD = 9.97 ± 3.86) than other retroperitoneal lesions (3.85 ± 1.51) or normal adrenal glands (3.91 ± 1.20). At an optimal cut-off of 6.57, the sensitivity, specificity, and accuracy of the quantitative assessment for 6-h SPECT/CT in differentiating PPGLs was 78.6%, 96.3%, and 92.6%, respectively; the area under the curve was 0.878. The diagnostic performance did not significantly differ between the quantitative and visual analyses, but the specificity of the former tended to be higher at 6 h (96.3% vs. 90.7%) and at 24 h (91.2% vs. 82.4%).


CONCLUSIONS
The specificity, but not the sensitivity, of the quantitative approach was higher than that of visual assessment in differentiating PPGLs from other retroperitoneal pathologies and from physiological uptake in the normal adrenal gland.
From the Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Ryusuke
R
Nakamoto
Yuji
Y
Nakamoto
Takayoshi
T
Ishimori
Kaori
K
Togashi
D019797:3-Iodobenzylguanidine; D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000311:Adrenal Glands / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004428:Ear Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010235:Paraganglioma / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D010673:Pheochromocytoma / Q000000981:diagnostic imaging*; D012372:ROC Curve; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012186:Retroperitoneal Neoplasms / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000072098:Single Photon Emission Computed Tomography Computed Tomography; D015899:Tomography, Emission-Computed, Single-Photon; D001749:Urinary Bladder Neoplasms / Q000000981:diagnostic imaging*; D055815:Young Adult
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine