Validation of Postoperative Angiofibroma Radionuclide Imaging Study (PARIS) Protocol Using PSMA PET/CT-A Proof of Concept Study.

Alok Thakar, Pirabu Sakthivel, Sreedharan Thankarajan Arunraj, Ashu Seith Bhalla, Arun Prashanth, Rakesh Kumar, Suresh Chandra Sharma, Rakesh Kumar

Clinical nuclear medicine 2021 May 01

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Juvenile nasopharyngeal angiofibroma (JNA) expresses prostate-specific membrane antigen (PSMA), and PSMA PET/CT scan may be used for its imaging. Also, the precise diagnosis of residual/recurrent JNA after surgical treatment remains difficult with conventional contrast MRI and/or CT; functional imaging with PSMA PET/CT promises greater accuracy in the detection or exclusion of recurrent/residual JNA. In this prospective study, 22 postoperative JNA patients who underwent a PSMA PET/CT scan both preoperatively and postoperatively from January 2018 to September 2020 were included. All patients underwent a low-dose head and neck spot PET/CT imaging. Abnormal postcontrast enhancement of a definite lesion was considered residual/recurrent tumor in contrast-enhanced MRI (CEMRI). In PSMA PET/CT, any abnormal uptake apart from physiological sites in the head and neck was considered as residual lesions. Radiological results were categorized as negative, suspicious for residual lesions, or definite residual/recurrent tumors. PSMA PET/CT findings were considered as the radiological standard, and patients were managed accordingly. The sensitivity, specificity, positive predictive value, and negative predictive value were separately calculated for CEMRI and PSMA PET/CT for diagnosing residual lesions. On postoperative CEMRI evaluation, 12 patients had residual tumors, 2 had normal suspicious scans, and 8 had normal postoperative scans. On PSMA PET/CT, only 7 patients had residual tumors and 15 had normal postoperative scans. In 1 patient with a residual tumor on both scans, a discrepancy was noted concerning tumor extent, and PSMA PET/CT accurately mapped the tumor. The sensitivity, specificity, positive predictive value, and negative predictive value of CEMRI were 100%, 53.33%, 41.67%, and 100%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of PSMA PET/CT were 100% for all parameters. Because CEMRI is oversensitive and less specific compared with PSMA PET/CT, Postoperative Angiofibroma Radionuclide Imaging Study (PARIS) protocol should be used always. In residual tumors, PSMA PET/CT has an outright advantage over CEMRI in the diagnosis, tumor mapping, decision making, planning stereotactic radiation, and aiding in future follow-ups. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

Citation

Alok Thakar, Pirabu Sakthivel, Sreedharan Thankarajan Arunraj, Ashu Seith Bhalla, Arun Prashanth, Rakesh Kumar, Suresh Chandra Sharma, Rakesh Kumar. Validation of Postoperative Angiofibroma Radionuclide Imaging Study (PARIS) Protocol Using PSMA PET/CT-A Proof of Concept Study. Clinical nuclear medicine. 2021 May 01;46(5):e242-e249