Study DesignRetrospective study.PurposeThis study aims to semiquantitatively evaluate the standardized uptake value (SUV) of 99mTc-methylene diphosphonate (MDP) radionuclide tracer in the normal vertebrae of breast cancer patients using an integrated single-photon emission computed tomography (SPECT)/computed tomography (CT) scanner.Overview of LiteratureMolecular imaging techniques using gamma cameras and stand-alone SPECT have traditionally been utilized to evaluate metastatic bone diseases. However, these methods lack quantitative analysis capabilities, impeding accurate uptake characterization.MethodsA total of 30 randomly selected female breast cancer patients were enrolled in this study. The SUV mean (SUVmean) and SUV maximum (SUVmax) values for 286 normal vertebrae at the thoracic and lumbar levels were calculated based on the patients’ body weight (BW), body surface area (BSA), and lean body mass (LBM). Additionally, 106 degenerative joint disease (DJD) lesions of the spine were also characterized, and both their BW SUVmean and SUVmax values were obtained. A receiver operating characteristic (ROC) curve analysis was then performed to determine the cutoff value of SUV for differentiating DJD from normal vertebrae.ResultsThe mean±standard deviations for the SUVmean and SUVmax in the normal vertebrae displayed a relatively wide variability: 3.92±0.27 and 6.51±0.72 for BW, 1.05±0.07 and 1.75±0.17 for BSA, and 2.70±0.19 and 4.50±0.44 for LBM, respectively. Generally, the SUVmean had a lower coefficient of variation than the SUVmax. For DJD, the mean±standard deviation for the BW SUVmean and SUVmax was 5.26±3.24 and 7.50±4.34, respectively. Based on the ROC curve, no optimal cutoff value was found to differentiate DJD from normal vertebrae.ConclusionsIn this study, the SUV of 99mTc-MDP was successfully determined using SPECT/CT. This research provides an approach that could potentially aid in the clinical quantification of radionuclide uptake in normal vertebrae for the management of breast cancer patients.

Superscan on PET/CT has been reported in the literature and mainly involved metastatic diseases. We report an uncommon case of a metabolic superscan on ¹⁸F-FDG PET/CT in a 56-year-old man with end-stage renal disease on hemodialysis who presented with secondary hyperparathyroidism. Parathyroid scintigraphy showed 2 lesions posteroinferior to both thyroid lobes, suggestive of parathyroid adenoma/hyperplasia. FDG PET/CT performed to assess for pulmonary nodules revealed diffuse FDG hypermetabolism involving the visualized skull, mandible, spine, sternum, ribs, and appendicular skeleton without corresponding CT lesion with no urinary radiotracer excretion, consistent with metabolic superscan secondary to renal osteodystrophy.

A 57-year-old woman received radioiodine therapy post total thyroidectomy for pT3aNxMx follicular thyroid carcinoma. Posttherapy ¹³¹I whole-body scan showed ¹³¹I concentration in the chest, mediastinum, and left upper thigh with stimulated thyroglobulin (Tg) of 89 μg/L. Subsequent radioiodine therapies showed persistent ¹³¹I accumulation in the anterior mediastinal soft tissue lesions and a hypodense segment VII liver lesion visualized on SPECT/CT, suggestive of iodine-avid metastatic disease despite the undetectable serum Tg (<1.0 μg/L) with no Tg antibody interference. Biopsy of the liver lesion revealed liver cyst, and consequent removal of the mediastinal lesions showed benign thymic cysts.

Study Design: Retrospective study.Purpose: To compare and correlate technetium-99m methylene diphosphonate uptake between benign and metastatic bone lesions using semiquantitative analysis of maximum standard uptake value (SUVmax) and mean Hounsfield unit (HU) in single-photon emission computed tomography-computed tomography (SPECT-CT).Overview of Literature: Qualitative interpretation of metastatic bone lesions in breast cancer on bone scintigraphy is often complicated by coexisting benign lesions.Methods: In total, 185 lesions were identified on bone and SPECT-CT scans from 32 patients. Lesions were classified as metastatic (109 sclerotic lesions) and benign (76 lesions) morphologically on low-dose CT. Semiquantitative analysis using SUVmax and mean HU was performed on the lesions and compared. To discriminate benign and metastatic lesions, the correlation between SUVmax and mean HU was determined using the intraclass correlation coefficients.Results: The SUVmax was higher in metastatic lesions (20.66±14.36) but lower in benign lesions (10.18±12.79) (p<0.001). The mean HU was lower in metastatic lesions (166.62±202.02) but higher in benign lesions (517.65±192.8) (p<0.001). A weak negative correlation was found between the SUVmax and the mean HU for benign lesions, and a weak positive correlation was noted between the SUVmax and the mean HU on malignant lesions with no statistical significance (p=0.394 and 0.312, respectively). The cutoff values obtained were 10.8 for SUVmax (82.6% sensitivity and 84.2% specificity) and 240.86 for the mean HU (98.7% sensitivity and 88.1% specificity) in differentiating benign from malignant bone lesions.Conclusions: Semiquantitative assessment using SUVmax and HU can complement qualitative analysis. Metastatic lesions had higher SUVmax but lower mean HU than benign lesions, whereas benign lesions demonstrated higher mean HU but lower SUVmax. A weak correlation was found between the SUVmax and the mean HU on malignant and benign lesions. Cutoff values of 10.8 for the SUVmax and 240.86 for the mean HU may differentiate bone metastases from benign lesions.

Objective: To compare the radiochemical synthesis, stability, and clinical performance of cyclotron-produced [ ¹⁸ F]PSMA-1007 and [⁶⁸Ga]PSMA-11 for prostate-specific membrane antigen (PSMA)-targeted PET/computed tomography (CT) imaging in prostate cancer. Methods: Six production runs each of [¹⁸F]PSMA-1007 and [⁶⁸Ga]PSMA-11 were conducted using a cyclotron-based system. Radiochemical yield, radiochemical purity, and product stability were evaluated according to European Pharmacopeia standards. Thirty-five patients with prostate cancer underwent dual-tracer PET/CT imaging within 30 days. Images were assessed for lesion detectability, biodistribution, and pitfalls by three independent nuclear medicine physicians using semiquantitative metrics. Results: [¹⁸F]PSMA-1007 demonstrated substantially higher end-of-synthesis activity (mean: 75.68 GBq) compared with [⁶⁸Ga]PSMA-11 (mean: 1.76 GBq), with both achieving high RCP (>98%) and comparable synthesis durations. Stability testing confirmed [¹⁸F]PSMA-1007 remained radiochemically stable for up to 9 h. Clinically, both tracers showed high concordance in PSMA-avid lesion detection. [¹⁸F]PSMA-1007 exhibited superior contrast in prostate and skeletal lesions because of minimal urinary excretion but also revealed higher rates of benign uptake in ganglia and nonspecific bone sites, leading to increased discordant findings (104 vs. 47 lesions). Conclusion: [¹⁸F]PSMA-1007 provides significant advantages in production scalability and lesion detectability, particularly in skeletal and pelvic regions; however, its higher rate of benign uptake necessitates careful interpretation to avoid false positives. While both tracers are clinically effective, tracer selection should be guided by logistical feasibility, clinical context, and interpretive considerations.

Rohani MF, et al. Cardiovasc Imaging Asia. 2019 Jan;3(1):27-29. https://doi.org/10.22468/cvia.2018.00241