False-Positive Bone Pitfall Lesion and Collateral Circulation: Don't Miss the True-Positive Lesion.

ABSTRACT: We report the case of a patient followed up for squamous cell carcinoma of the buccal floor with lymph node involvement. The initial staging PET/CT revealed bone foci that were not definitively pathological in the context of a regional collateral circulation secondary to a defibrillator. A new monitoring examination, conducted due to the rapid local progression, revealed a dissociated evolution of the bone uptake adjacent to the collateral circulation, some confirming false-positives, but one indicating a real metastasis. This case illustrates that bone uptakes without morphological lesions adjacent to a collateral circulation are not easily interpretable.

False-Positive Bone Lesion With Different PET/CT Tracers: Beyond Thrombosis, Be Aware of Any Collateral Circulation.

ABSTRACT: Collateral circulation is often secondary to a regional thrombosis. This phenomenon can lead to the detection of misleading bone lesions on imaging and is a well-known source of false-positives. Here, we present 2 different tracers PET/CT images, 18F-FDG and 18F-choline, with collateral circulation but without obvious thrombosis. Both cases displayed bone uptake, which mimicked metastasis. However, clinical follow-up ruled out metastasis and revealed false-positive bone lesions related to collateral circulation, even in the lack of acute or chronic underlying thrombotic processes.

Radionuclide Therapy With 177 Lu-PSMA in a Patient With Hepatocellular Carcinoma.

ABSTRACT: A 69-year-old man diagnosed with progressive bone metastatic castration-resistant prostate adenocarcinoma and concurrent alcoholic cirrhosis with multiple hepatocellular carcinoma (HCC) nodules was referred to our nuclear medicine service for 177 Lu-PSMA-617 therapy. The patient's pretreatment screening using 68 Ga-PSMA-11 PET/CT revealed high prostate-specific membrane antigen expression in both prostatic and HCC lesions. The patient underwent 2 doses of 177 Lu-PSMA-617. Subsequent imaging assessments with 68 Ga-PSMA-11 PET/CT and hepatic MRI indicated progressive HCC nodules, while showing a partial response in prostatic bone metastases. Positive clinical and biological responses were observed only in prostatic disease, but not in HCC nodules.

A False-Positive Bone Oligometastatic Prostate Cancer in 18 F-Choline PET/CT : Be Aware of Chronic Vascular Pitfalls.

ABSTRACT: We report the case of a 71-year-old man undergoing initial assessment for a high-risk group prostate adenocarcinoma. His medical history includes gastric carcinoma treated with surgery and chemotherapy. 18 F-choline PET/CT was performed for initial staging and displayed several intense foci uptake of sternum and thoracic vertebrae, suggestive of bone metastasis. Because of a chronic right jugulosubclavian confluent thrombosis related to his implantable chamber, a control was performed 3 weeks later. It showed spontaneous disappearance of those uptakes, consistent with pitfalls related to the collateral circulation induced by the chronic right subclavian vein thrombosis, despite the chronic anticoagulation.

Rationale for Prostate-Specific-Membrane-Antigen-Targeted Radionuclide Theranostic Applied to Metastatic Clear Cell Renal Carcinoma.

Prostate-specific membrane antigen (PSMA), whose high expression has been demonstrated in metastatic aggressive prostate adenocarcinoma, is also highly expressed in the neovessels of various solid tumors, including clear cell renal cell carcinoma (ccRCC). In the VISION phase III clinical trial, PSMA-targeted radioligand therapy (PRLT) with lutetium 177 demonstrated a 4-month overall survival OS benefit compared to the best standard of care in heavily pretreated metastatic prostate cancer. Despite the improvement in the management of metastatic clear cell renal cell carcinoma (mccRCC) with antiangiogenic tyrosine kinase inhibitor (TKI) and immunotherapy, there is still a need for new treatments for patients who progress despite these drugs. In this study, we discuss the rationale of PRLT applied to the treavtment of mccRCC.

Intense Diffuse Lung Uptake Due to Interstitial Pneumopathy Related to Polyangiitis Granulomata in 68 Ga-PSMA-11 PET/CT.

ABSTRACT: We reported the case of a 73-year-old man for whom a prostatic adenocarcinoma with synchronous bone metastases was diagnosed. Because his disease was progressing despite several lines of chemotherapy and hormonotherapy, he was screened with a 68 Ga-PSMA PET/CT for a possible 177 Lu-PSMA-617 therapy. The examination demonstrated an intense diffuse bone uptake related to the known bone involvement. It also showed an unexpected diffuse and intense lung uptake, secondary to an active polyangiitis granulomata. This intense lung uptake prohibits the radioligand therapy.

18F-Fluorocholine PET and 4D-CT in Patients with Persistent and Recurrent Primary Hyperparathyroidism.

Patients with primary hyperparathyroidism (pHPT) can develop persistent (P-pHPT) or recurrent (R-pHPT) disease after parathyroidectomy. Before recommending reoperation, recurrence must be accurately identified because of the high risk of complications. Our study evaluates 18F-fluorocholine (18F-FCH) PET/CT and 4D-CT integrated in PET/4D-CT in patients with P-pHPT/R-pHPT. Patients with P-pHPT/R-pHPT investigated by 18F-FCH PET/4D-CT between May 2018 and March 2021 were retrospectively included. Forty-two patients were included, 37 of whom underwent 4D-CT. The sensitivity and detection rate (DR%) were 95% and 88% for 18F-FCH PET/CT and 70% and 63% for 4D-CT, respectively. PET/CT and 4D-CT were concordant in 18/24 glands and concordant and positive in 15/24 (63%) glands. Discordant results were obtained for 6/24 glands. The surgical success rate was 65%. PET/CT showed significantly higher sensitivity than 4D-CT. Dynamic CT allowed the identification of no additional glands missed by PET/CT, and the combination of the 2 techniques did not improve the sensitivity or DR%. 18F-FCH PET/CT appears to be a valuable technique to accurately detect hyperfunctioning parathyroid tissue in patients with P-pHPT/R-pHPT and is better than 4D-CT. Except for cases with doubtful locations of PET targets that may require 4D-CT for surgical guidance, standard nonenhanced 18F-FCH PET/CT can be effectively recommended in patients with P-pHPT/R-pHPT before reoperation.

Advantages of 18F-FDG PET/CT Imaging over Modified Duke Criteria and Clinical Presumption in Patients with Challenging Suspicion of Infective Endocarditis.

According to European Society of Cardiology guidelines (ESC2015) for infective endocarditis (IE) management, modified Duke criteria (mDC) are implemented with a degree of clinical suspicion degree, leading to grades such as "possible" or "rejected" IE despite a persisting high level of clinical suspicion. Herein, we evaluate the 18F-FDG PET/CT diagnostic and therapeutic impact in IE suspicion, with emphasis on possible/rejected IE with a high clinical suspicion. Excluding cases of definite IE diagnosis, 53 patients who underwent 18F-FDG PET/CT for IE suspicion were selected and afterwards classified according to both mDC (possible IE/Duke 1, rejected IE/Duke 0) and clinical suspicion degree (high and low IE suspicion). The final status regarding IE diagnosis (gold standard) was based on the multidisciplinary decision of the Endocarditis Team, including the 'imaging specialist'. PET/CT images of the cardiac area were qualitatively interpreted and the intensity of each focus of extra-physiologic 18F-FDG uptake was evaluated by a maximum standardized uptake value (SUVmax) measurement. Extra-cardiac 18F-FDG PET/CT pathological findings were considered to be a possible embolic event, a possible source of IE, or even a concomitant infection. Based on the Endocarditis Team consensus, final diagnosis of IE was retained in 19 (36%) patients and excluded in 34 (64%). With a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and global accuracy of 79%, 100%, 100%, 89%, and 92%, respectively, PET/CT performed significantly better than mDC (p = 0.003), clinical suspicion degree (p = 0.001), and a combination of both (p = 0.001) for IE diagnosis. In 41 patients with possible/rejected IE but high clinical suspicion, sensitivity, specificity, PPV, NPV, and global accuracies were 78%, 100%, 100%, 85%, and 90%, respectively. Moreover, PET/CT contributed to patient management in 24 out of 53 (45%) cases. 18F-FDG PET/CT represents a valuable diagnostic tool that could be proposed for challenging IE cases with significant differences between mDC and clinical suspicion degree. 18F-FDG PET/CT allows a binary diagnosis (definite or rejected IE) by removing uncertain diagnostic situations, thus improving patient therapeutic management.

18F-Fluorocholine PET and Multiphase CT Integrated in Dual Modality PET/4D-CT for Preoperative Evaluation of Primary Hyperparathyroidism.

The present retrospective study evaluates the diagnostic value of integrated 18F-Fluorocholine positron emission tomography/four-dimensional contrast-enhanced computed tomography (18F-FCH PET/4D-CT) as second-line imaging in preoperative work-up of primary hyperparathyroidism (pHPT), and compares 18F-FCH PET with 4D-CT. Patients with pHPT and negative/discordant first-line imaging addressed for integrated 18F-FCH PET/4D-CT were retrospectively selected. Sensitivity and detection rate (DR%) of 18F-FCH PET/CT, 4D-CT, and PET/4D-CT were calculated according to the per patient and per lesion analyses, and afterwards compared. Histology associated with a decrease more than 50% of perioperative parathyroid hormone (PTH) blood level was used as a gold standard. Persistent high serum PTH and calcium levels during a 6-month follow-up was considered as presence of pHPT in both operated and non-operated patients. 50 patients (55 glands) were included. 44/50 patients (88%) were surgically treated. On a per patient analysis, sensitivity was 93%, 80%, and 95%, and DR% was 82%, 68%, and 84%, respectively for PET/CT, 4D-CT, and PET/4D-CT. PET/CT was more sensitive than 4D-CT (p = 0.046). PET/4D-CT performed better than 4D-CT (p = 0.013) but was equivalent to PET/CT alone. On a per gland analysis, sensitivity PET/CT, 4D-CT, and PET/4D-CT was 88%, 66%, and 92%, and DR% was 79%, 57%, and 83%, respectively. PET/CT and PET/4D-CT were more sensitive than 4D-CT alone (p = 0.01, p < 0.001, respectively). However, PET/CT and PET/4D-CT performed similarly. In conclusion, 18F-FCH PET provides better identification of hyperfunctioning parathyroids than 4D-CT and the combination of both did not significantly improve diagnostic sensitivity. Further investigations involving larger populations are necessary to define the role of 18F-FCH PET/4D-CT as a "one-stop shop" second-line imaging in preoperative work-up of pHPT, especially considering the additional patient radiation exposure due to multi-phase CT.