FDG-PET in Chimeric Antigen Receptor T-Cell (CAR T-Cell) Therapy Toxicity: A Systematic Review

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.

Assessment of regional and total skeletal metabolism using 18F-NaF PET/CT in patients with chronic kidney disease

OBJECTIVE

The study aims to assess regional and total bone metabolic activity in patients with chronic kidney disease using Na[18F]F PET and correlation between semi-quantitative indices and blood parameters.

METHODS

Seventy-two subjects (mean age 61.8 ± 13.8 years) were included. Of these 24/72 patients had end-stage renal disease (ESRD) (GFR < 15 mL/min/1.73 m2), 38/72 had chronic kidney disease (CKD) (GFR between 60 and 15 mL/min/1.73 m2), and 10/72 were controls with normal renal function. All subjects underwent Na[18F]F PET-CT with a dose activity of 0.06 mCi/Kg. Regional and total skeletal metabolism were assessed with mean SUVs in a skeletal volume of interest (VOI), bone to soft tissue index (B/S), global SUV mean (GSUV mean) of the whole bone, and uptake in the femoral neck.

RESULTS

Statistically significant differences were observed in a number of 18F-NaF metrics like femoral neck metabolism in CKD and ERSD groups in comparison to control in right (P = 0.003) and left femur (P = 0.006), bone to soft tissue index in the femur (P = 0.016) and GSUV5 (P = 0.006). There is also a significant difference in SUV mean in lumbar vertebrae (L1-L4) among CKD, ESRD, and controls. There was a moderate correlation between 18F-NaF PET scan uptake and blood parameters such as ALP and PTH. Na[18F]F uptake parameters were significantly different in low versus high bone turnover state.

CONCLUSIONS

The assessment of total skeleton and regional metabolism and bone turnover in CKD patients is feasible with Na[18F]F PET. Na[18F]F can help to detect early changes in bone metabolism and assess the progression of bone disease in this complex condition. Quantification with Na[18F]F PET might provide better assessment of the bone turnover. The difference in Na[18F]F uptake in CKD compared to controls is likely related to a change in bone turnover which, however, requires further validation.

Krukenburg tumour: Role of 18F-FDG PET/CT in identifying the primary site

Krukenberg tumours are a rare form of metastatic tumours of the ovary. They primary site is usually the gastro-intestinal system with the most common being gastric cancer. We present the case of a 35-year-old female coming in with a large pelvi-abdominal mass for investigation. This pelvic mass showed mild to moderate metabolic activity. 18F-FDG PET-CT was able to identify the primary gastric carcinoma. Subsequent histopathology confirmed this to be gastric adenocarcinoma with metastases to the ovary.

The Great Imitator: Pulmonary Paraganglioma Mimicking Pulmonary Metastasis of Breast Cancer on 18 F-FDG PET/CT

ABSTRACT

Primary pulmonary paragangliomas are rare neuroendocrine tumors and are often discovered incidentally as nonfunctioning masses. We report a case of 58-year-old woman recently diagnosed with multifocal right breast cancer and suspicious right axillary lymph nodes. 18 F-FDG PET/CT showed a well-defined marginated lesion in the lower lobe of the right lung with intense FDG uptake. Findings were suspicious for pulmonary metastases. CT-guided biopsy results were consistent with a paraganglioma. Paragangliomas can mimic metastases, especially if they are large or have a high degree of FDG uptake, and careful evaluation of imaging features and clinical findings can help differentiate these entities. Most of the time biopsy is necessary to confirm the diagnosis.

18 F-FDG PET/CT Imaging of Pulmonary Hamartomas : Metabolic and Functional Characterization

ABSTRACT

Pulmonary hamartoma is the most common benign tumor of the lung and often discovered incidentally on imaging. We report the case of a 49-year-old woman recently diagnosed with left breast cancer with suspicious left axillary lymph nodes. 18 F-FDG PET/CT showed well-circumscribed, lobulated, low-attenuation soft tissue mass in the right lower lobe lung with mild to no significant metabolic activity. CT-guided biopsy showed the lesion composed of fat, cartilage, and smooth muscle, admixed with fibroconnective tissue. The findings are consistent with pulmonary hamartoma. The presence of fat in a well-circumscribed solitary pulmonary nodule along with low metabolic activity helps in the characterization of the lesion, which can alter patient management.

Radiation in a New Era of Multiple Myeloma Management: Patterns of Utilization, Clinical, Radiologic, and Biochemical Outcomes, and Possible Genomic Correlates of Response

PURPOSE/OBJECTIVE(S)

Systemic therapies for multiple myeloma (MM) have advanced considerably, improving patient outcomes. Yet, the use of radiotherapy (RT) has remained heterogeneous, and even controversial, due to minimal data on outcomes. With the ultimate goal of guiding the design of prospective trials incorporating RT, we initiated a study of our institutional experience treating MM with RT since 1/1/2000. Here we report a preliminary feasibility analysis of an initial sample cohort, identifying patterns of RT utilization, outcomes, and impact of RT on radiographic and biochemical markers, with genomic characterization for more recently treated patients.

MATERIALS/METHODS

Five hundred six pathologically confirmed MM patients who received RT to 1190 sites between January 1, 2000, and June 1, 2022, were identified. Patient, disease, and treatment characteristics were analyzed for 50 consecutive patients treated in 2019 and tested for association with local and distant failure (LF, DF) using univariable and multivariable analysis. Genomic data was obtained via next generation sequencing using an institutional targeted sequencing panel.

RESULTS

Amongthe 50 patients analyzed (median 63 years), 90 lesions were treated with RT, 33% with concurrent systemic therapy, to median dose of 20 Gy (8-46 Gy) over a median of 5 fractions (1-25). RT Indications were pain (56%), critical structure involvement (25%), peri-operative (9%), salvage/consolidation (8%), and bridging therapy (2%). Median size of RT-treated lesions was 4.2 cm (1.4-7.9) and included non-vertebral bones (62%), spine (24%), and extramedullary sites (14%). The median number of lines of pre-RT therapy was 7 (1-14) and 51% had >9 lesions on imaging, 47% involving both medullary and extramedullary sites. With median follow-up of 12.4 months (0.5-46), LF occurred in 5% of treated sites and 89% had DF, most commonly in both medullary + extramedullary (51.4%) sites. Absolute decreases 1-week to 1-month post-RT were observed in % of marrow plasma cell (median 4.0%), M spike (0.30 g/dL), total protein (0.3 g/dL), K:L ratio (0.01), lesion size (1.5cm), and lesion SUV (3.1) but in this limited sample, none were significantly associated with disease control. A cohort of 62 RT-treated MM patients from 2016-2022 had genomic data available; most common tumor mutations were in TP53 (35%), HIST1 (34%), NRAS (34%), and KRAS (23%).

CONCLUSION

In this pilot analysis of a sampling cohort of RT-treated MM, we report on patterns of utilization, outcomes, and biochemical and radiographic correlates. At the meeting, we will present the full analysis of the >500 MM patients and further analyze emerging genomic data. We aim to characterize the role of RT in the modern era of systemic therapy to guide the design of future prospective trials and to inform novel approaches for incorporating RT into the treatment paradigm.

68Ga-DOTA-peptide PET/CT for radiotherapy planning and evaluating treatment response in the management of meningiomas

Meningiomas overexpress somatostatin receptors (SSTR). PET imaging with SSTR ligands such as 68Ga-DOTA-peptide has recently shown high diagnostic accuracy in identification of meningiomas due to lack of normal bone and brain activity. PET-derived parameters, especially gross tumour volume (GTV) delineation improves inter-observer variability and appears to be particularly promising for RT planning. The potential strength of 68Ga-DOTA in the ongoing assessment of treatment response and disease progression in meningioma, particularly in the post-surgical and post-radiation settings is encouraging. More prospective randomized studies with large cohorts of patients are required to define the effective role of this modality.

Tumour sink effect on 68Ga-PMSA PET/CT: A case of diffuse metastatic disease of prostate cancer

68Ga-PMSA imaging has revolutionized both diagnosis and radioligand therapy selection in patients with metastatic prostate cancer. We report a case of a 59-year-old recently diagnosed prostate cancer with high PSA level pf >2000ng/ml referred for 68Ga-PSMA PET/CT. 68Ga-PSMA PET/CT showed diffuse intense tracer uptake throughout the axial and appendicular skeleton with significantly lower uptake of 68Ga-PSMA in normal organs in a configuration of "tumour sink effect". Findings are in keeping with diffuse skeletal infiltration and suspected marrow infiltration. Given the extensive nature of bone disease and pattern, 177Lu-PSMA-targetted radioligand therapy was thought to be more appropriate in a given situation with a favourable toxicity profile.

Accumulation of 18F-FDG at Anomalous Systemic Arterial Supply to Normal Lung on 18F-FDG PET/CT

ABSTRACT

Anomalous systemic arterial supply to normal lung is an anatomical variant in which a portion of the lung is supplied by a systemic vessel without a distinct pulmonary sequestration. We report a case of mild to moderate accumulation of 18F-FDG in the medial basal segment of left lung; corresponding CT images localize this uptake in the tortuous artery arising from the descending aorta with similar uptake to that of descending aorta. Findings are suggestive of anomalous systemic arterial supply to normal segments of the lung. Hybrid PET/CT allows precise anatomical localization and helps in differentiate benign mimics of disease, which can alter patient management.

Accumulation of 131Iodine in the nasolacrimal sac/duct after radioiodine therapy for papillary thyroid cancer

SPECT/CT is a powerful tool for assessing unexpected concentrations of radioiodine resulting from benign uptake in organs with sodium-iodide symporter (NIS) expression. We report a case of accumulation of 131Iodine in the nasolacrimal sac/duct after radioiodine therapy for papillary thyroid cancer. A whole-body scan was taken 3 days after the administration of 5.5 GBq of 131Iodine. SPECT/CT images localized the focal tracer uptake in the nasolacrimal sac/duct likely due to nasolacrimal duct obstruction secondary to prior radioiodine or iodine therapies. Hybrid SPECT/CT allows precise anatomical localization and help differentiate benign mimics of disease, which can alter patient management.

Paediatric metastatic ganglioneuroblastoma on 68Ga-DOTA NOC PET-CT

68Ga-DOTA NOC PET-CT imaging has been shown to have high accuracy for the evaluation of neuroendocrine tumours. We report a case of a 3-year-old boy who presented with a right paravertebral soft tissue mass. Biopsy showed ganglioneuroblastoma. The patient was referred for 68Ga-DOTA NOC for staging. 68Ga-DOTA NOC PET/CT images showed somatostatin-avid large right paravertebral soft tissue mass representing the primary lesion, along with increased radiotracer localization at multiple metastatic lytic bone lesions in the axial and appendicular skeleton. 68Ga-DOTA NOC PET-CT is helpful in the evaluation of the disease extent of neuroendocrine tumours including ganglioneuroblastoma.

Prospective study of Na[18F]F PET/CT for cancer staging in morbidly obese patients compared with [99mTc]Tc-MDP whole-body planar, SPECT and SPECT/CT

PURPOSE

This prospective study aims to assess the diagnostic test characteristics of Na[¹⁸F]F PET/CT for the skeletal staging of cancer in morbidly obese patients compared with ^99mTc-methylene diphosphonate (MDP), whole-body planar (WBS), SPECT, and SPECT/CT acquisitions.

MATERIAL AND METHODS

One hundred seventeen obese patients (BMI 46.5 ± 6.1 kg/m² and mean age, 59.0 years; range 32-89 years) with BMI > 40 kg/m² were prospectively enrolled and underwent [^99mTc]Tc-MDP WBS, SPECT, SPECT/CT, and Na[¹⁸F]F PET/CT within two weeks for the osseous staging of a malignancy. Images were assessed qualitatively using a 3-point scale. Patient and lesion-based diagnostic test characteristics were estimated using an optimistic and pessimistic dichotomization method.

RESULTS

Bone metastases were confirmed in 44 patients. Patient-based optimistic diagnostic test characteristics were (sensitivity, specificity, overall accuracy): Na[¹⁸F]F PET/CT (95.5%, 95.9%, 95.7%), [^99mTc]Tc-MDP WBS (52.3%, 71.2%, 64.1%), SPECT (61.4%, 80.8%, 73.5%) and SPECT/CT (65.9%, 91.8%, 82.1%). Lesion-based optimistic diagnostic test characteristics were: Na[¹⁸F]F PET/CT (97.7%, 97.9%, 97.7%), [^99mTc]Tc-MDP WBS (39%, 67%, 48.9%), SPECT (52.9%, 93.6%, 67.3%) and SPECT/CT (65.9%, 91.8%, 82.1%). There was no significant difference in the specificity of Na[¹⁸F]F and SPECT/CT. All other pairwise comparisons were significant (p<.001). ROC curve analysis showed a high overall accuracy of Na[¹⁸F]F with significantly higher AUCs for Na[¹⁸F]F PET/CT compared to [^99mTc]Tc-MDP WBS, SPECT, and SPECT/CT on both patient and lesion-based analysis (p<.001). Moreover, Na[¹⁸F]F PET/CT changed patient management in 38% of patients.

CONCLUSIONS

Na[¹⁸F]F PET/CT may be the preferred imaging modality for skeletal staging in morbidly obese patients. The technique provides excellent diagnostic test characteristics superior to [^99mTc]Tc-MDP bone scan (including SPECT/CT), impacts patient management, has an acceptable radiation exposure profile, and is well-tolerated. Further cost-effectiveness evaluations are warranted.

Functional Characterization of Posttraumatic Heterotopic Ossification of Tibiofibular Syndesmosis with Dynamic Bone Scan and Single-Photon Emission Computed Tomography/Computed Tomography

A 53-year-old man was investigated for ongoing right ankle pain and lateral malleolus swelling following a traumatic inversion injury 12 weeks prior. The initial ankle radiograph was normal with no evidence of fracturing. The follow-up radiograph showed bridging ossification in the distal tibiofibular syndesmosis. As the pain did not subside, posttraumatic heterotopic ossification (HO) was suspected, and triple-phase dynamic bone imaging with technetium 99m-methylene diphosphonate was performed to guide further management. The bone scan revealed intense focal tracer activity centered on the HO of the tibiofibular syndesmosis, with no evidence of occult fracturing confirming HO as a pain generator.

Primary Breast Lymphoma Mimicking Metastatic Breast Cancer on 18F-FDG PET-CT

18F-Fluorodeoxyglucose (FDG) PET-CT is an excellent imaging modality for the evaluation of non-Hodgkin lymphoma (NHL). We report a case of a 45-year-old woman presented with a large right breast mass and suspicious right axillary lymph nodes referred for 18F-FDG PET-CT for staging. 18F-FDG PET-CT images show large hypermetabolic right breast mass infiltrating the skin, multiple hypermetabolic right axillary and subpectoral lymph nodes, along with multiple hypermetabolic bone lesions at axial and appendicular skeleton. Findings are mimicking primary breast cancer with nodal and bone metastases. Biopsy revealed diffuse large B cell lymphoma. 18F-FDG PETCT is helpful in evaluation of disease extent and response evaluation of primary breast lymphoma.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. ¹⁸F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, ¹⁸F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as ¹⁸F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

18F-PSMA-1007 Uptake in Paget Disease of the Bone: An "Iron Man" Sign

ABSTRACT

18F-PSMA is a promising tracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the benign pathological conditions. We report a case of 81-year-old man with a known case of prostate cancer who underwent 18F-PSMA for restaging. 18F-PSMA PET/CT shows intense tracer uptake in the frontal bone appearing like an "Iron Man" sign. Corresponding noncontrast CT images, pagetoid changes with thickened cortex, mixed lytic/sclerotic mottled pattern. It is important to recognize 18F-PSMA expression in the benign nonprostatic pathologies to avoid false interpretation.

Case of Adult Metastatic Medulloblastoma Demonstrated on 18F-DOPA PET/CT

ABSTRACT

18F-DOPA is a promising radiotracer used for both staging and restaging of primary brain tumors based on increased transport via the L-type large neutral amino acid transport system in tumor cells. Adult medulloblastoma is extremely rare. We present a case of 25-year-old man with posterior fossa medulloblastoma treated with surgery followed by chemotherapy and radiotherapy 5 years back, which later developed metastasis to left cerebral lobe treated with gamma knife followed by surgical debulking. Recent 18F-DOPA PET/CT demonstrates recurrence and disease progression on follow-up scan. 18F-DOPA PET/CT is extremely useful for characterizing brain tumors, response assessment, and prognosis.

Prostate-Specific Membrane Antigen Expression in Metastatic Angiosarcoma Detected on 18F-PMSA PET/CT: A New Potential Prognostic Marker

ABSTRACT

18F-PSMA is a promising tracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the endothelium of tumor-associated neovasculature of various solid malignancies possibly due to tumor-associated angiogenic factors and endothelial cell sprouting. We report a case of a 59-year-old man with known case of prostate cancer underwent 18F-PSMA for restaging. 18F-PSMA PET/CT shows multiple lytic bone lesions with high PSMA expression. Histopathological evaluation showed metastatic angiosarcoma. 18F-PSMA expression in the angiosarcoma can be potentially guided to radionuclide legend therapy.

Excellent Response to Adapted Low-Dose 177Lu-PSMA-617 PSMA Therapy in Renal Compromise Patient

ABSTRACT

Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy with 177Lu-PSMA-617 has shown promising results in patients with metastasized castration-resistant prostate cancer. We report a case of a 74-year-old man with metastatic prostate cancer with comorbidities of diabetes mellitus, hypertension, and chronic kidney disease. In order to minimize radiation burden to kidneys, a lower dose of 4 GBq of 177Lu-PSMA-617 was prescribed instead of the usual 6 to 7 GBq. There was significant decrease in prostate-specific antigen levels and symptoms. Renal profile remained stable. This case highlights that compromised renal function is not a definite contraindication to radionuclide therapy, and doses can be modified based on risk versus benefits.

18F-FDG PET Uptake in the Scalp After Platelet-Rich Plasma Therapy

ABSTRACT

18F-FDG PET/CT has been found useful for the detection of the source of infection/inflammation in the body. Platelet-rich plasma is a new treatment modality in which plasma is injected subdermally or intradermally for potential hair regrowth into the scalp. We report a case of 43-year-old woman with right breast cancer who underwent surgery, chemotherapy, and radiotherapy 2 years ago and is currently on hormonal therapy. 18F-FDG PET/CT demonstrate incidental findings of increased FDG avidity in the scalp after platelet-rich plasma therapy.

Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Hodgkin's Lymphoma: Diagnostic Challenge during COVID Vaccination

Benign metabolic uptake on fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) is not uncommonly seen after immunization. We report a case of 30-year-old man with Hodgkin's lymphoma who underwent two cycles of chemotherapy. Interim ¹⁸F-FDG PET/computed tomography demonstrated complete metabolic response of prior hypermetabolic bilateral supraclavicular and mediastinal lymph nodes. Although multiple new normal-sized hypermetabolic left axillary and subpectoral lymph nodes are noted, relevant history revealed COVID vaccine 7 days prior scan with mild FDG uptake at the left deltoid muscle. These new findings at the left axilla are likely related to recent vaccination. ¹⁸F-FDG PET uptake in the lymph nodes is not so uncommon after immunization; relevant history is very important especially in the phase of massive immunization to avoid false interpretation.

18F-Sodium Fluoride (NaF) Uptake in Calcified Bladder Carcinoma: Double Density Sign

¹⁸F-Sodium fluoride (NaF) is primarily a skeletal imaging agent which can be localized in extraosseous calcified foci. Here, we describe a case of a 48-year-old man with bladder carcinoma referred for staging using ¹⁸F-NaF positron emission tomography/computed tomography (PET/CT). ¹⁸F-NaF PET/CT detected a calcified soft tissue mass in the urinary bladder. Extraosseous ¹⁸F-NaF uptake is often encountered and these non-osseous findings could possibly provide important diagnostic information. Thus, recognition of extraosseous ¹⁸F-NaF activity has implications for accurate staging and management.

Occult Bone Metastases From Hepatocellular Carcinoma Detected on 68Ga-PMSA PET/CT

ABSTRACT

68Ga-PSMA is an excellent radiotracer for both staging and detection of recurrence in prostate cancer, but it can also be useful in other solid tumors due to tumor-associated angiogenic factors and endothelial cell sprouting. We report a case of an 82-year-old man with hepatocellular carcinoma who presented with rising tumor marker but stable CT findings 6 months after transarterial chemoembolization. 68Ga-PSMA PET/CT showed high PSMA-expressing hyperneovascular hepatic lesions (primary tumor), additional multifocal hepatic lesions, and with unexpected multiple bone metastases. 68Ga-PSMA expression in hepatocellular carcinoma can influence patient management and potentially guide radionuclide legend therapy.

Symptomatic Os Navicular on 99mTc-MDP SPECT/CT

Os navicular bone is an accessory bone of the foot, which is mainly found on the medial side of the proximal navicular bone. Os navicular bone may be symptomatic and cause medial foot pain. We report a case of a 42-year-old athlete male having right foot pain diagnosed with os navicular syndrome on 99mTc-MDP bone scintigraphy SPECT/CT. We emphasize on the use of SPECT/CT in not only allocating the ossicle anatomically, but also for the purpose of evaluating an active source of pain in a region of multiple complex small bones.

COVID-19 Vaccination Manifesting as Incidental Lymph Nodal Uptake on 18F-FDG PET/CT

ABSTRACT

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.

Thyroid Cancer Detected on 68Ga-PMSA PET/CT

Ga-68 PSMA is a promising radiotracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the endothelium of tumour-associated neo vasculature of various solid malignancies possibly due to tumour-associated angiogenic factors and endothelial cell sprouting. We report a case of 72-yearold male with known prostate cancer on follow-up with mild increase in serum PSA level. 68Ga-PSMA PET-CT showed large PSMA avid mass in the left thyroid lobe, histopathology revealed papillary carcinoma. 68Ga-PSMA expression in the thyroid carcinoma potentially guide to radionuclide legend therapy with α/β- emitters specially in iodine refractory cases.

The clinical effectiveness of reconstructing 18F-sodium fluoride PET/CT bone using Bayesian penalized likelihood algorithm for evaluation of metastatic bone disease in obese patients

OBJECTIVE

A new Bayesian penalized likelihood reconstruction algorithm for positron emission tomography (PET) (Q.Clear) is now in clinical use for fludeoxyglucose (FDG) PET/CT. However, experience with non-FDG tracers and in special patient populations is limited. This pilot study aims to compare Q.Clear to standard PET reconstructions for ¹⁸F sodium fluoride (¹⁸F-NaF) PET in obese patients.

METHODS

30 whole body ¹⁸F-NaF PET/CT scans (10 patients with BMI 30-40 Kg/m² and 20 patients with BMI >40 Kg/m²) and a NEMA image quality phantom scans were analyzed using ordered subset expectation maximization (OSEM) and Q.Clear reconstructions methods with B400, 600, 800 and 1000. The images were assessed for overall image quality (IQ), noise level, background soft tissue, and lesion detectability, contrast recovery (CR), background variability (BV) and contrast-to-noise ratio (CNR) for both algorithms.

RESULTS

CNR for clinical cases was higher for Q.Clear than OSEM (p < 0.05). Mean CNR for OSEM was (21.62 ± 8.9), and for Q.Clear B400 (31.82 ± 14.6), B600 (35.54 ± 14.9), B800 (39.81 ± 16.1), and B1000 (40.9 ± 17.8). As the β value increased the CNR increased in all clinical cases. B600 was the preferred β value for reconstruction in obese patients. The phantom study showed Q.Clear reconstructions gave lower CR and lower BV than OSEM. The CNR for all spheres was significantly higher for Q.Clear (independent of β) than OSEM (p < 0.05), suggesting superiority of Q.Clear.

CONCLUSION

This pilot clinical study shows that Q.Clear reconstruction algorithm improves overall IQ of ¹⁸F-NaF PET in obese patients. Our clinical and phantom measurement results demonstrate improved CNR and reduced BV when using Q.Clear. A β value of 600 is preferred for reconstructing ¹⁸F-NaF PET/CT with Q.Clear in obese patients.

ADVANCES IN KNOWLEDGE

¹⁸F-NaF PET/CT is less susceptible to artifacts induced by body habitus. Bayesian penalized likelihood reconstruction with¹⁸F-NaF PET improves overall IQ in obese patients.

18F-Sodium Fluoride PET/CT Findings in Osteitis Condensans Ilii

ABSTRACT

Osteitis condensans ilii (OCI) is a benign cause of low back pain for which no clear etiology has been identified. We report cases of 2 women with breast cancer referred for 18F-NaF PET/CT for skeletal staging. Both cases show characteristic findings of OCI on CT images, with 18F-NaF PET uptake in symptomatic patient and no uptake in asymptomatic. 18F-NaF PET CT can be useful in evaluating back pain and may be used as an adjunctive biological maker for assessing OCI as a potential cause of pain.

68Ga-Prostate-Specific Membrane Antigen Uptake as a Surrogate Biomarker of Neovascularity in Hepatocellular Carcinoma

⁶⁸Ga-prostate-specific membrane antigen (⁶⁸Ga-PSMA) is expressed in the endothelium of tumor-associated neovasculature of various solid malignancies possibly due to tumor-associated angiogenic factors and endothelial cell sprouting. We report a case of a 45-year-old man with known colorectal cancer, cirrhosis, and hepatitis C. Contrast-enhanced computed tomography (CT) showed a hypervascular lesion in the liver, and ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) did not show any suspicious hepatic uptake. ⁶⁸Ga-PSMA PET-CT showed predominantly heterogeneous perilesional uptake in a configuration similar to the arterial enhancement pattern on the diagnostic CT. ⁶⁸Ga-PSMA uptake in hepatocellular carcinoma appears to be primarily neoangiogenesis driven, and its morphological and functional characterization can subsequently influence the selection of anti-neoangiogenic chemotherapy agents as well as guiding radionuclide ligand therapy.

Lessons from a theory of change-driven evaluation of a global mental health funding portfolio

BACKGROUND

Given the underinvestment in global mental health to-date, it is important to consider how best to maximize the impact of existing investments. Theory of Change (ToC) is increasingly attracting the interest of funders seeking to evaluate their own impact. This is one of four papers investigating Grand Challenges Canada's (GCC's) first global mental health research funding portfolio (2012-2016) using a ToC-driven approach.

METHODS

A portfolio-level ToC map was developed through a collaborative process involving GCC grantees and other key stakeholders. Proposed ToC indicators were harmonised with GCC's pre-existing Results-based Management and Accountability Framework to produce a "Core Metrics Framework" of 23 indicators linked to 17 outcomes of the ToC map. For each indicator relevant to their project, the grantee was asked to set a target prior to the start of implementation, then report results at six-month intervals. We used the latest available dataset from all 56 projects in GCC's global mental health funding portfolio to produce a descriptive analysis of projects' characteristics and outcomes related to delivery.

RESULTS

12,999 people were trained to provide services, the majority of whom were lay or other non-specialist health workers. Most projects exceeded their training targets for capacity-building, except for those training lay health workers. Of the 321,933 people screened by GCC-funded projects, 162,915 received treatment. Most projects focused on more than one disorder and exceeded all their targets for screening, diagnosis and treatment. Fewer people than intended were screened for common mental disorders and epilepsy (60% and 54%, respectively), but many more were diagnosed and treated than originally proposed (148% and 174%, respectively). In contrast, the three projects that focused on perinatal depression exceeded screening and diagnosis targets, but only treated 43% of their intended target.

CONCLUSIONS

Under- or over-achievement of targets may reflect operational challenges such as high staff turnover, or challenges in setting appropriate targets, for example due to insufficient epidemiological evidence. Differences in delivery outcomes when disaggregated by disorder suggest that these challenges are not universal. We caution implementers, funders and evaluators from taking a one-size-fits all approach and make several recommendations for how to facilitate more in-depth, multi-method evaluation of impact using portfolio-level ToC.

Spectrum of false positive 18F-sodium fluoride (NaF) bone PET/CT findings in Oncology imaging; A narrative pictorial review of cases from a single institution

Fluorine-18-sodium fluoride (¹⁸F-NaF) is a positron emission tomography (PET) bone imaging agent mainly used for oncology staging but may also be used in the evaluation of benign bone and joint pathology conditions. Fluorine-18-NaF is an excellent bone-seeking agent with high bone uptake owing to favorable biodistribution with rapid single-pass extraction, limited plasma protein binding and prompt renal clearance. Fluorine-18-NaF PET/computed tomography (CT) is highly sensitive in identifying both sclerotic and lytic bone metastatic lesions. Occasionally ¹⁸F-NaF uptake in benign bone lesions can mimic malignantpathology. In these cases, the pattern of ¹⁸F-NaF uptake may elicit a specific diagnosis and correlation with clinical information and morphological information from correlative CT is essential for a correct diagnosis. In the present article, we present a series of clinical cases demonstrating examples of ¹⁸F-NaF uptake in benign lesions which can simulate malignant pathology in patients undergoing cancer staging.

A rare case of Diffuse Large B-Cell Lymphoma of the Prostate on 18F-FDG PET-CT

18F-Fluorodeoxyglucose (FDG) PET-CT is an excellent imaging modality for the evaluation of Non-Hodgkin lymphoma. We report a case of 65-year-old man with haematuria; rectal examination and ultrasonography revealed prostate mass. Staging 18F-FDG PET-CT images showed a large hypermetabolic, infiltrative prostate mass. Subsequent contrast enhanced CT images showed ill-defined heterogeneously enhancing fungiform mass with irregular outline involving the prostate, base of urinary bladder as well as the seminal vesicles. Biopsy showed diffuse large B cell lymphoma. 18F-FDG PET-CT is helpful in evaluation of disease extent and therapy response.

18F-NaF PET/CT of Obese Patients on a Lutetium-Yttrium Oxyorthosilicate PET/CT System: Patient Dosimetry, Optimization of Injected Activity, and Acquisition Time

¹⁸F-NaF PET/CT has a rapid single-pass extraction and fast clearance from soft tissues, resulting in a good target-to-background ratio. This study aimed to establish the optimum acquisition time and dosimetry for ¹⁸F-NaF PET/CT to evaluate bone metastases in obese patients. A secondary objective was to evaluate the impact of acquisition time on image quality, lesion detection rate, noise level, and radiation burden in this patient group. Methods: In total, 60 patients were included in the study (20 patients with a body mass index (BMI) of 30.0-34.9 kg/m², 20 with a BMI of 35-39.9 kg/m², and 20 with a BMI of >40 kg/m²). Images were acquired after intravenous injection of a 2.2 MBq/kg (0.06 mCi/kg) dose of ¹⁸F-NaF. Data were acquired in list mode using ordered-subset expectation maximization reconstruction. The raw data were rebinned to simulate scans with acquisition times of 2, 2.5, and 3 min per bed position. The scans were visually analyzed by 2 observers and scored by rank against a panel of parameters (overall image quality, noise level, background soft tissue, and lesion detectability), and the contrast-to-noise ratio (CNR) was calculated. Results: The mean CNR was 20.19 ± 8.39 for a 2-min acquisition, 21.03 ± 8.35 for 2.5 min, and 22.16 ± 8.37 for 3 min. There were no statistically significant differences in CNR among the 3 different acquisition durations (P > 0.05). Lesion delineation was excellent and independent of the acquisition time. All relevant lesions could be identified with all 3 acquisition times. A mean activity of 215.4 ± 31.3 MBq was injected, with estimated mean effective absorbed doses of 4.09 ± 0.59 mSv for ¹⁸F-NaF PET and 7.88 ± 1.66 mSv for CT alone. Conclusion: ¹⁸F-NaF PET/CT can be beneficial in obese patients because of its good pharmacokinetics. Optimal osseous staging can be achieved with relatively low doses and radiation burden. Lesion delineation was excellent regardless of acquisition time. However, it is recommended that an acquisition of 3 min per bed position be used in patients with a BMI of more than 40.

Rare Thyroid Cartilage Metastasis From Breast Cancer Visualized on 18F-NaF PET/CT

Metastatic involvement of the thyroid cartilage is rare due to the absence of vessels within the cartilaginous tissue. We present the case of a 65-year-old woman recently diagnosed with breast cancer referred for skeletal staging with F-NaF PET/CT. She was found to have multiple osteoblastic metastases along with thyroid cartilage metastasis. Rare thyroid cartilage metastasis on F-NaF PET/CT may have prognostic significance in cancer patients.

Incremental Value of Post Diuretic 68Ga-PSMA-11 PET-CT in Characterization of Indeterminate lLesions in Prostate Cancer

Objective:

The aim of current study is to evaluate the role of diuretic assisted ⁶⁸Ga-PSMA PET-CT, on image quality and clinical interpretation of indeterminate/equivocal lesions in pre-Lasix imaging of Prostate cancer.

Materials and Methods:

Forty-five patients underwent baseline ⁶⁸Ga-PSMA-11 scan 45-60 minutes post tracer injection followed by post Lasix study after ±15 minutes. The contrast to noise ratios (CNR), noise and SUVmax were determined for the focal uptakes in both pre and post Lasix images. All continuous variables were expressed as mean ± SD. Images were assessed by two experienced physicians in order to evaluate lesion detectability and delineations that have an impact on clinical interpretation.

Results:

Of total 45 patients, 12/45 (27%) showed unremarkable scan along with 33/45 (73%) showing metastases. Sixteen out of 45 (36%) of the metastatic scans showed indeterminate/equivocal lesions. In these cases, post Lasix study showed false negative findings in 7/45 (16%), better delineation of lesions 10/45 (22%), better confidence towards reporting lesions as abnormal in 5/45 (11%) with an overall 11/45 (24%) of the cases who showed increase in the number of the lesions after the Lasix study. The overall CNR was evaluated using Wilcoxon Rank test (p-value = 0.02) which suggested significant improved ratios in the post-Lasix imaging by 49.6%±24.5. There was a substantial agreement (k =0.76) between the physicians when comparing the lesion clarity and delineation in post Lasix images. The average score for physician one and two being 2.4 ±0.71 and 2.53±0.52 respectively.

Conclusion:

Post diuretic ⁶⁸Ga-PSMA imaging at ± 15 minutes clears the unwanted activity in the urinary tract which in turn improves the contrast to noise ratios. Thus leading to decline in false positive findings, improved diagnostic certainty of physician and better detection of indeterminate lesions in ⁶⁸Ga-PSMA imaging.

Extensive Extramedullary Hematopoiesis in Thalassemia: Soft Tissue Uptake on 99mTc-MDP SPECT/CT

We report the case of a 45-year-old man with thalassemia major referred for a bone scan as a workup for generalized bone pain. Tc-MDP SPECT CT showed multiple elongated soft tissue masses along the inner aspects of ribs and along both sides of dorsal spine with calcification and mild tracer uptake. There was also a large lobulated presacral soft tissue mass displacing the bladder and involving the adjacent pelvic bone. Biopsy of mildly avid tracer uptake in pelvic soft tissue mass was extramedullary hematopoiesis confirmed by biopsy.

A Very Unusual Pattern of Intraperitoneal and Extraperitoneal Heterotropic Splenic Tissue-Mimicking Metastases Identified on 68Ga-DOTA-NOC Positron Emission Tomography/Computed Tomography and 99mTc Heat-denatured Erythrocyte Study

The dissemination and autotransplantation of viable splenic tissue in different anatomic compartments of the body can present a diagnostic dilemma, especially when metastatic disease is suspected. We report a case of a 30-year-old male with well-differentiated gastric neuroendocrine tumor (Grade II) treated with surgery. Follow-up ⁶⁸Ga-DOTA-NOC demonstrated a suspicious peritoneal soft-tissue nodule in the right paracolic gutter with increased tracer uptake. In view of splenectomy 10 years ago, the patient underwent ^99mTc heat-denatured erythrocyte study which showed a very unusual pattern of multiple tracer-avid foci of splenic tissue in both intraperitoneal and extraperitoneal distributions. The integration of the patient's history and complementary nuclear imaging results led to the correct diagnosis of splenosis.

Incidental brain metastasis of breast cancer detected on 18F-Sodium Fluoride (NaF) PET-CT

18F- Sodium Fluoride (NaF) is an excellent bone imaging agent used for skeletal staging but can also be localized in extra osseous calcifying lesions. We report a case of a 38-year-old woman with breast carcinoma referred for 18F-NaF PET-CT to evaluate possible metastatic lesions. 18F-NaF PET-CT detected incidental focal soft tissue tracer uptake in the right cerebellum with no sign of calcification seen on CT images. Subsequent MRI show high intensity signal lesion confirming brain metastasis. Extra osseous 18F-NaF uptake may provide important diagnostic information that might alter patient management.

Textitis as Seen on 18F-NaF Imaging Using an Ultra-High-Resolution Positron Emission Mammography Scanner

Textitis is a new term used to refer to the degenerative-strain osteoarthritis that comes from excessive use of a smart phone. ¹⁸F-NaF is increasingly used in diagnosing skeletal pain that is not identified on radiographs. We report a case of a 26-y-old woman with left breast cancer referred for ¹⁸F-NaF PET/CT, who was complaining of right thumb and wrist pain. Findings were negative for bone secondaries. Dedicated hands views were acquired on a positron emission mammography scanner and showed focal uptake at the first carpometacarpal and second metacarpophalangeal joints. On the basis of the strong history, the findings were likely due to active arthritic changes caused by repetitive strain injury from excessive text messaging.

Significance of 18F-FDG PET/CT in Characterization of Equivocal Lesions in High-Risk Testicular Carcinoma in Restaging Setting

Objectives:

The present study aims to evaluate the role of Positron emission tomography (PET) -computed tomography (CT) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) in the restaging of high-risk testicular cancer.

Methods:

Forty-five patients (mean age of 38.1±11.3 years and range 23-81 years) with testicular carcinoma, underwent ¹⁸F-FDG PET-CT during their clinical course were prospectively selected. PET positivity was defined as a site of abnormal ¹⁸F-FDG uptake in tissue histologically proven or clinically or radiographically suspected to represent tissue involvement. The sites of disease were characterized as either nodal or extranodal. All patients were followed-up for at least 12 months with a diagnostic and/or functional imaging modality.

Results:

Of the 45 patients 38 (84%) patient presented with seminoma and 7 (16%) were Non-seminomatous germ cell tumors. Analysis of secondary disease spectrum showed nodal involvement in 65%, osseous involvement in 23% and mixed visceral/soft tissue lesions in 12% of patients. Nineteen (42%) were negative for any metastatic disease. All negative patients remain disease free in the follow-up of one year. Out of the positive 26/45 patients, PET-CT showed progressive disease in 3/26, stable disease 1/26 and partial response in 2/26 and complete metabolic resolution in 20/26 patients. ¹⁸F-FDG PET-CT was able to characterize all patients leading to significant change of primary decision of wait and watch to go for treatment and vice versa.

Conclusion:

¹⁸F-FDG PET-CT scan is potentially an excellent tool for characterization of equivocal lesions on CT scan in the restaging settings and follow up of high-risk testicular cancer patients.

Molecular imaging of bone metastases using bone targeted tracers

Molecular imaging using bone targeted tracers has been used in clinical practice for almost fifty years and still plays an essential role in the diagnosis and follow-up of bone metastases. It includes both [99mTc]bisphosphonates for bone scan and [18F]NaF for positron emission tomography/computed tomography (PET/CT) which are very sensitive to detect osteoblastic activity, but it is important to consider several aspects to increase the specificity of reported findings (such as specific tracer characteristics and mechanism of action, patient's clinical history, common metastatic patterns, changes after treatment, limitations of the technique, variations and pitfalls). This will enable useful information for clinical management being provided in the report. Furthermore, iatrogenic skeletal adverse events are common and they should also be identified, as they have impact on patient's quality of life. This review makes a brief summary of the mechanism of action of bone targeted tracers, followed by a discussion of classic patterns of bone metastasis, treatment response assessment and iatrogenic skeletal complications. The value of hybrid imaging techniques with bone targeted tracers, including single photon emission computed tomography and PET/CT is also explored. The final part summarizes new bone targeted tracers with superior imaging characteristics that are being developed, and which may further enhance the applications of radionuclide bone imaging.

Tc-99m HDP Single Photon Emission Computed Tomography/Computed Tomography in Stress Fracture of Base of Metatarsal Bone

Proximal metatarsal stress fractures are common at base of the second metatarsal, typically seen in repetitive impact athletes, dancers, and those with cavus feet. It is caused by increased bone resorption rather than formation in a state of abrupt increased physical activity or intensity, leading to repetitive microfractures and eventually stress fracture. It is characterized by swelling and tenderness of a prolonged duration. We report a case of a 40-year-old female having left foot pain diagnosed with stress fracture on Tc-99m HDP single-photon emission computed tomography (SPECT)-CT. We emphasize the use of SPECT/CT in allocating active source of pain in the feet.

225Ac Prostate-Specific Membrane Antigen Posttherapy α Imaging: Comparing 2 and 3 Photopeaks

Ac-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.

Neuroendocrine differentiation in castration resistant prostate cancer. Nuclear medicine radiopharmaceuticals and imaging techniques: A narrative review

BACKGROUND

Androgen Deprivation Therapy (ADT) is the primary treatment for patients suffering from relapsing or advanced prostate cancer (PC). Hormone therapy generally guarantees adequate clinical control of the disease for some years, even in those patients affected by widespread skeletal and soft tissue metastases. Despite ADT, however, most patients treated with hormones eventually progress to castration-resistant prostate cancer (CRPC), for which there are no effective treatments. This clinical reality is an open challenge to the oncologist because of those neoplasms which elaborate neuroendocrine differentiation (NED).

METHODS

An online search of current and past literature on NED in CRPC was performed. Relevant articles dealing with the biological and pathological basis of NED, with nuclear medicine imaging in CRPC and somatostatin treatment in NED were analyzed.

EVIDENCE FROM THE LITERATURE

NED may arise in prostate cancer patients in the late stages of ADT. The onset of NED offers prognostic insight because it reflects a dramatic increase in the aggressive nature of the neoplasm. Several genetic, molecular, cytological and immunohistochemical markers are associated with this transformation. Among these, overexpression of somatostatin receptors, seen through Nuclear Medicine testing, is one of the most studied.

CONCLUSIONS

Preliminary studies show that the overexpression of somatostatin receptors related to NED in CRPC may easily be studied in vivo with PET/CT. This finding offers a potentially useful objective for targeted therapy in CRPC. If the overexpression of SSTRs is shown to afflict a significant segment of patients with CRPC, this will open further study of possible therapeutic options based on this marker.

Immune checkpoint inhibitors (Nivolumab)-induced enterocolitis demonstrated on 18Fluorine-fluorodeoxyglucose positron emission tomography-computed tomography

Nivolumab, an immune checkpoint inhibitor, is a humanized anti-programmed death-1 monoclonal antibody that is used for the treatment of various cancers after second-line chemotherapy. We report a 23-year-old male with relapsed Hodgkin's lymphoma Stage IV treated with nivolumab. After 3 months of treatment, he developed watery diarrhea and cramping abdominal pain. Follow-up positron emission tomography-computed tomography scan showed complete metabolic resolution of the disease; however, there is bowel wall thickening and colonic distension with corresponding increased fluorodeoxyglucose uptake. These findings are related to immune-related adverse event associated with nivolumab treatment, i.e., secondary enterocolitis. These adverse events can be successfully treated if timely and appropriately diagnosed.

Adductor Insertion Avulsion Syndrome with Stress Fracture in Morbidly Obese Patient Diagnosed on 18F-Sodium Fluoride Positron Emission Tomography-Computed Tomography

Adductor insertion avulsion syndrome, also known as “thigh splints,” is a painful condition affecting the proximal to mid-femur at the insertion of the adductor muscles of the thigh. ¹⁸F-Sodium fluoride (¹⁸F-NaF) is increasingly used in diagnosing skeletal pain which is not identified on radiographs. We report a case of a 56-year-old morbidly obese woman with left hip pain referred for ¹⁸F-NaF positron emission tomography–computed tomography (PET-CT) as magnetic resonance imaging cannot be performed due to obesity. ¹⁸F-NaF PET-CT shows an increase in tracer uptake at the posteromedial cortex of the upper shaft of left femur. Findings are likely due to adductor insertion avulsion syndrome. ¹⁸F-NaF provides important diagnostic information that might alter treatment options.