Clinical Utility of 68Ga-Prostate-Specific Membrane Antigen PET/CT Scan on Postoperative Assessment of Juvenile Nasal Angiofibroma

Negative 68Ga-Prostate-Specific Membrane Antigen PET/CT Scan on a Recurrent Juvenile Nasopharyngeal Angiofibroma

ABSTRACT

We present the case of a left-sided recurrent juvenile nasopharyngeal angiofibroma (JNA) in a 16-year-old boy who underwent endoscopic excision 2 years back. The preoperative contrast-enhanced MRI and histopathology were in favor of JNA. The follow-up 68Ga-prostate-specific membrane antigen (PSMA) PET/CT scan at 3-month interval revealed complete clearance of disease. Currently, the patient presented with recurrent bleeding and nasal endoscopic examination, and contrast-enhanced MRI revealed a presence of a recurrent tumor. The tumor did not show any uptake on 68Ga-PSMA PET/CT, and postoperative histopathology evaluation confirmed the presence of JNA. Although regarded as a criterion-standard imaging modality for assessment of recurrent or residual JNA, 68Ga-PSMA PET/CT is never 100% specific.

Pterygoid Base Pneumatization Simulating Residual Disease-A Pitfall of Structural Imaging in Juvenile Nasal Angiofibroma

ABSTRACT

As prostate-specific membrane antigen (PSMA) expression is universal in juvenile nasopharyngeal angiofibroma, it is commonly used for specifically differentiating recurrences from surgical site reparative tissues. Postoperative contrast-enhanced MRI revealed a residual disease in the left pterygoid base, but there was no PET/CT uptake with 68Ga-labeled PSMA at the same site. In retrospect, in comparison with preoperative PET/CT, it was found that the pterygoid base pneumatization was showing enhancement in contrast-enhanced MRI and not in functional PSMA. Postoperative 68Ga-PSMA PET/CT is a useful clinical tool in ambivalent diagnostic conditions avoiding morbidities.

68Ga-PSMA PET/CT Scan on Postoperative Assessment of Sinonasal Glomangiopericytoma

ABSTRACT

Prostate-specific membrane antigen (PSMA) is expressed on the endothelial cells of tumor-associated neovasculature of various nonprostatic benign and malignant neoplasms. Positive intense uptake on PET/CT imaging with 68Ga-labeled PSMA is noted in a patient with sinonasal glomangiopericytoma, and the same is noted to be absent following complete surgical excision. 68Ga-PSMA PET/CT may be a useful tool for early recurrence identification, differentiating recurrence from surgical site reparative tissues, and peptide receptor radionuclide therapy of residual lesions.

Physiological PSMA Uptake in the Tubarial Salivary Glands and Its Implications in the PARIS Protocol-A First Study of Its Kind!

OBJECTIVES

Because prostate-specific membrane antigen (PSMA) expression is universal in juvenile nasal angiofibroma (JNA), PSMA PET/CT is commonly used in the postoperative setting using the postoperative angiofibroma radionuclide imaging study protocol. Our study aims to illustrate physiological PSMA ligand uptake distribution characteristics in the salivary glands, specifically the tubarial glands with tumor, to aid in accurate PSMA PET/CT analysis.

STUDY DESIGN

Forty-three consecutive patients who underwent a dedicated head and neck spot PSMA PET/CT for JNA were evaluated retrospectively. PSMA SUVmax values in the tumor, tubarial, parotid, submandibular, and sublingual salivary glands were determined visually and quantitatively.

RESULTS

All the tumors and the salivary glands showed increased tracer uptake. The median SUVmax ± SD ratios of the tumor, right and left tubarial gland, right and left parotid gland, right and left submandibular gland, and right and left sublingual gland were 2.7 ± 0.8 (range, 0.5-7.5), 3.8 ± 1.9 (range, 0.9-8.1), 4.7 ± 2.1 (range, 0.8-7.4), 9.5 ± 4.8 (range, 3.2-21.9), 9.2 ± 4.7 (range, 2.9-18.9), 10.4 ± 5.7 (range, 3.5-25.4), 10.4 ± 5.5 (range, 3.7-26.4), 6 ± 4.1 (range, 1.3-20.6), and 6.5 ± 4.2 (range, 1.8-19.7), respectively. The uptake in the tubarial glands was comparable with that of the tumor but less compared with other major salivary glands.

CONCLUSIONS

Ours is the first study demonstrating the quantitative uptake of tubarial salivary glands in detail. Because the tubarial glands uptake and the anatomical location are similar to that of the tumor, these physiological uptakes must be borne in mind to circumvent false-positive interpretations and care must be given during the planning of stereotactic radiotherapy for JNAs.

Fusion 68Ga-DOTANOC PET/MRI in Primary Juvenile Nasal Angiofibroma

ABSTRACT

Somatostatin cell surface receptors are expressed in many different benign and malignant tumors and are often exploited for imaging and therapy of neuroendocrine tumors. A 17-year-old adolescent boy with clinicoradiologically diagnosed JNA (juvenile nasopharyngeal angiofibroma) also underwent 68Ga-DOTANOC PET to explore somatostatin cell surface receptors' expression and its theranostic potential. Fusion PET/MRI, a novel imaging technology, exactly depicted the anatomical extensions of the tumor with avid DOTANOC uptake. This software-based fusion technique is advantageous for easy early recurrence identification, better delineation from postoperative scar tissue, for planning the exact target volumes for stereotactic radiotherapy therapy of inoperable/residual/recurrent JNAs in the future.

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

OBJECTIVES

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.

PATIENTS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Clinical utility of Ga68 DOTANOC PET/CT imaging in juvenile nasal angiofibroma and the PARIS protocol: a preliminary report

OBJECTIVES

Juvenile nasopharyngeal angiofibroma (JNA) expresses different somatostatin cell surface receptors and Ga68 [DOTA, 1-Nal3]-octreotide (DOTANOC)-PET/computed tomography (CT) scan may be used for its imaging. Also, functional imaging with DOTANOC-PET/CT may promise of greater accuracy in the detection or exclusion of recurrent/residual JNA.

METHODS

In this prospective study, five JNA patients who underwent a DOTANOC-PET-CT scan both preoperatively and postoperatively during June 2018-March 2020 were included. Postcontrast enhancement of a definite lesion was considered residual/recurrent tumor in contrast-enhanced MRI (CEMRI). In DOTANOC-PET/CT, any abnormal uptake apart from physiological sites was considered as residual lesions. Radiological results were categorized as negative, suspicious or definite residual/recurrent tumors. Any discrepancy was resolved by endoscopic biopsies.

RESULTS

Preoperatively all five cases of JNA showed avid DOTANOC expression in the tumor. The mean (SD) value of DOTANOC standardised uptake value in the tumor was 4.3 (1.4) (range = 2.1-6.2). In postoperative CEMRI evaluation, three of five patients had residual tumors and two had normal scans. On DOTANOC-PET/CT, two of five patients had residual tumors and three had normal scans. In one patient with residual tumor, the discrepancy with regard to tumor extent was noted in two scans, and further biopsy confirmed the findings of DOTANOC-PET/CT as accurate.

CONCLUSION

68Ga-DOTANOC-PET/CT uptake is universal in JNA and appears to be more specific in the identification of residual/recurrent JNA. In residual tumors, DOTANOC-PET/CT may have an advantage over CEMRI in the diagnosis, decision making and planning stereotactic radiation. However, these findings are to be validated in studies with larger patients.

Advantage of 68Ga-PSMA PET/CT on Postradiotherapy Response Assessment of Juvenile Nasal Angiofibroma

ABSTRACT

Prostate-specific membrane antigen (PSMA) is universally expressed in the endothelial cells of tumor-associated neovasculature of juvenile nasopharyngeal angiofibroma. Functional 68Ga-PSMA PET/CT also enables easier differentiation of the residual tumor from postoperative changes. An 18-year-old man with the residual intracranial disease received radiotherapy after surgery. In PSMA PET/CT imaging, uptake was noted initially only in the residual disease, and the same was absent after successful response to radiotherapy, unlike contrast MRI, which showed persistent enhancement. Functional 68Ga-PSMA PET/CT may be a very useful tool clinically for identifying early responses to radiotherapy compared with conventional structural imaging.

Comparison of Prostate-Specific Membrane Antigen PET/CT and Contrast-Enhanced Magnetic Resonance Imaging in Follow-up Assessment of Juvenile Nasal Angiofibroma-A Novel Pilot Study

PURPOSE/BACKGROUND

The specific identification of residual/recurrent juvenile nasal angiofibroma (JNA) following surgical treatment remains difficult. Contrast MRI and CT may not enable the differentiation of tumor from postsurgical reparative tissue. Functional imaging with prostate-specific membrane antigen (PSMA) PET/CT targeting tumor-associated neovasculature has recently demonstrated universal positive uptake in primary JNA and offers promise of greater accuracy in the detection or exclusion of recurrent/residual JNA.

METHODS

In this prospective study, 18 postsurgical JNA patients with high suspicion for residual disease evinced by follow-up MR scan, or nasal endoscopy, or recent epistaxis during September 2018-November 2019 were included. All patients underwent head and neck spot PSMA PET/CT imaging. Postcontrast enhancement of a definite lesion was considered as a criterion for 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, and residual/recurrent tumors. Any discrepancy between CEMRI and PSMA was resolved by surgical biopsies. The sensitivity, specificity, and positive and negative predictive values were separately calculated for CEMRI and PSMA PET/CT for diagnosing residual lesions. The interrater agreement κ value was also calculated.

RESULTS

On CEMRI evaluation, 14 of 18 patients had residual tumors, 2 had suspicious residual lesions, and 2 had normal postoperative scans. On PSMA PET/CT, 12 of 18 patients had residual tumors, and 6 had normal negative scans. Surgical biopsy in all 4 discordant cases was negative for tumors and revealed only fibrosis. In 1 patient with residual tumor on both scans, discrepancy was noted with regard to tumor extent demonstrated by the 2 scans, and further surgical excision confirmed the imaging findings of PSMA PET/CT as accurate. The sensitivity, specificity, and positive and negative predictive values of CEMRI were 100%, 33.33%, and 75% and 100%, respectively. The sensitivity, specificity, and positive and negative predictive values of PSMA PET/CT were 100% for all parameters. The interrater agreement between the 2 tests (κ) is 0.5 (95% confidence interval, 0.19-0.81).

CONCLUSIONS

The Ga-PSMA PET/CT is noted as more specific than the current standard of CEMRI in the identification of residual/recurrent JNA. It is the first radionuclide imaging scan that has found application in postoperative assessment of JNA.

TRIAL REGISTRATION

Clinical Trials Registry of India (CTRI/2018/08/015479).

Clinical Utility of 68Ga-DOTANOC Positron Emission Tomography-Computed Tomography Scan on Postoperative Assessment of Juvenile Nasal Angiofibroma

Somatostatin cell surface receptors are expressed on the peritumoral vessels of various benign and malignant neoplasms including angiofibromas. Positive initial uptake on positron emission tomography-computed tomography (PET/CT) imaging with ⁶⁸Ga-labeled DOTANOC is noted in a patient with juvenile nasal angiofibroma (JNA), and the same is noted to be absent following complete surgical excision. Functional ⁶⁸Ga-DOTANOC PET/CT may be an early useful tool for JNA residual/recurrence identification and precise postoperative surveillance.

Clinical Applications of 68Ga-PSMA PET/CT on Residual Disease Assessment of Juvenile Nasopharyngeal Angiofibroma (JNA)

We present a case of a 16-year-old boy who underwent ⁶⁸Ga-PSMA PET/CT for residual disease assessment of juvenile nasal angiofibroma. Positive uptake was noted in residual tumor on PET/CT imaging. However, there was no abnormal uptake in surrounding scar tissues as compared with contrast-enhanced magnetic resonance imaging. These findings were confirmed by biopsy from the scar tissue on posterior ethmoids. ⁶⁸Ga-PSMA PET/CT may be a potentially valuable tool especially in distinguishing recurrences from surgical site reparative tissue and in planning and delivering stereotactic radiotherapy.