We report on a 62-year-old man with metastatic prostate cancer (cT3b N1) diagnosed in 2011, treated with total androgen blockage with flutamide and goserelin acetate (Zoladex). He presented with left suprascapular swelling and low-back pain after being asymptomatic for 5 years. His prostate-specific antigen was 0.049 ng/mL. 18F-NaF PET-CT and 68Ga-PSMA scan were negative, whereas 68Ga-DOTA NOC scan done after 10 days showed multiple somatostatin-avid hepatic and lymph node metastasis.

²²⁵Ac-based PSMA-targeted therapy has emerged as promising agent for the treatment of metastatic castration-resistant prostate cancer. Posttherapy image is used for tracer localization and dosimetry. Prior 2 photopeaks of 440 and 218 KeV were reported for posttherapy imaging. Our study of gamma ray spectrum, phantom, and clinical images show that imaging with 3 major photopeaks of 78, 218, and 440 KeV gives better quality images, high count statistics, and higher number of lesion delineations. It is therefore suggested that posttherapy imaging may be carried out using 3 major abundant photopeaks.

Benign uptake on ¹⁸F-FDG PET can be seen with inflammatory conditions. We report a case of an 86-year-old woman with successfully treated nasal melanoma who underwent routine follow-up ¹⁸F-FDG PET, day 6 after the second dose of Pfizer-BioNTech COVID-19 vaccine inoculated in the left deltoid muscle. ¹⁸F-FDG PET showed increase tracer uptake in the left deltoid muscle and in 2 normal-sized left subpectoral nodes. These findings were considered secondary to vaccination. With the current drive of global COVID-19 immunization, this case highlights the importance of documenting vaccination history at the time of scanning to avoid false-positive results.

Fluorine-18-sodium fluoride (18F-NaF) PET/CT is an important tool for detecting and evaluating metastatic bone cancer. Besides traditional dose metrics, recent methods such as real-time dose mapping, dose calculation from DICOM information, and their relevance to entrance skin exposure are currently in use to reduce the radiation burden. In this study, we have analyzed the data of 1062 patients retrospectively to evaluate patterns of absorbed dose for institutional weight-based dose protocol as compared with fixed dose method guidelines of Society of Nuclear Medicine and Molecular Imaging (SNMMI). The effective dose imparted by 18F-NaF (internal exposure) was calculated by using coefficient 0.089 mrem/mCi (0.024 mSv/MBq) according to ICRP publication 106. To estimate the effective dose from whole-body CT scan (external exposure), volume CT dose index (mGy) and dose length product (mGy cm) were directly obtained from the display screen of CT workstation. Effective dose was calculated by multiplying DLP (mGy cm) with ICRP conversion coefficient ‘k’ 0.015 (mSv/mGy cm). Of the total 1062 patients, there were metastases in 44% (464), probable malignancy in 9% (96), negative findings in 40.5% (433), equivocal findings in 3% (32), and probable benignancy in 3.5% (37). All patients were injected with an institutional agreed protocol of 2.22 MBq/kg (0.06 mCi/kg). The mean injected activity for entire population came out to be 4.79±0.99 mCi. The mean effective absorbed doses were 3.37±0.70 and 5.5±1.35 mSv for 18F-NaF alone and CT alone, respectively. The mean cumulative effective dose of combined 18F-NaF PET and CT scan was calculated to be 8.8±1.8 mSv. The minimum absorbed dose for our method was as follows: 1.37 mSv for Kuwait Cancer Control Center vs. 4.44 mSv for SNMMI. Absorbed dose for maximum injected activity was as follows: 5.7 mSv for Kuwait Cancer Control Center vs. 8.88 mSv for SNMMI. Our weight-based doses were also lower when compared with minimum and maximum absorbed doses of technetium-99m-methylene diphosphonate as per SNMMI guidelines (i.e. 4.21 and 6.32 mSv, respectively). Our weight-based dose protocol showed a significant reduction in absorbed doses (i.e. 69.14% for 18F-NaF and 67.45% for technetium-99m-methylene diphosphonate) when compared with fixed dose method guidelines of SNMMI. It is suggested that further prospective studies may be performed in adult population, to evaluate dosimetry efficacy of 18F-NaF at a low dose of 0.06 mCi/kg as inferred in our current study.

The utilization of chimeric antigen receptor (CAR) T-cell therapy to target cluster of differentiation (CD)19 in cancer immunotherapy has been a recent and significant advancement. Although this approach is highly specific and selective, it is not without complications. Therefore, a systematic review was conducted to assess the current state of positron emission tomography (PET) in evaluating the adverse effects induced by CAR T-cell therapy. A thorough search of relevant articles was performed in databases such as PubMed, Scopus, and Web of Science up until March 2024. Two reviewers independently selected articles and extracted data, which was then organized and categorized using Microsoft Excel. The risk of bias and methodological quality was assessed. In total, 18 articles were examined, involving a total of 753 patients, in this study. A wide range of utilities were analyzed, including predictive, correlative, and diagnostic utilities. While positive outcomes were observed in all the mentioned areas, quantitative analysis of the included studies was hindered by their heterogeneity and use of varying PET-derived parameters. This study offers a pioneering exploration of this promising field, with the goal of encouraging further and more focused research in upcoming clinical trials.