Comparison of positional artifacts in myocardial perfusion imaging in supine and semi-reclining position using dedicated D-SPECT cardiac camera: validation using CT based attenuation correction.

BACKGROUND: Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols. METHODS: We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image. RESULTS: In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments. CONCLUSION: The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images.

Isolated Rectal Metastases from Locally Advanced Carcinoma Prostate Detected by 18 F-PSMA-1007 PET/CT.

Rectal involvement by prostate carcinoma is rare and isolated rectal metastases are even rarer with only a few cases having been reported in the literature. In our knowledge, no case of isolated rectal metastases diagnosed on prostate specific membrane antigen positron emission tomography/computed tomography has been reported to date. We present a case of a 66-year-old patient who presented with rectal bleeding and passage of urine from anal region and was diagnosed with carcinoma prostate infiltrating the rectum along with solitary rectal metastases.

Applicability of Adults 2015 American Thyroid Association Differentiated Thyroid Cancer Guidelines for Postoperative Risk Stratification and Postradioiodine Treatment Dynamic Risk Stratification in Pediatric Population.

Purpose This retrospective study aimed to study the applicability of 2015 adult American Thyroid Association (ATA) differentiated thyroid cancer (DTC) postoperative risk stratification and guidelines in the pediatric population for evaluating the number of metastatic lymph nodes in the postoperative risk stratification and postradioactive iodine (RAI) treatment dynamic risk stratification (DRS) using response to treatment (RTT) reclassification. In addition, the effect of pubertal status and gender was assessed on disease presentation and prognosis. Methods Data of 63 DTC patients aged 20 years or less, stratified into prepubertal, pubertal, and postpubertal age groups, was divided into low, intermediate, and high-risk groups using pediatric ATA recurrence risk stratification. Forty-seven patients were classified as responders (excellent and indeterminate responses) and incomplete responders (biochemical and structurally incomplete responses) by assessing the RTT at 1.5 years follow-up similar to recommendation of 2015 adult DTC ATA guidelines. Results Female-to-male ratio showed a trend of gradual increase with increasing age. Significantly more responders were observed in low- and intermediate-risk groups than in high-risk group ( p = 0.0013; p = 0.017, respectively), while prepubertal group had more extensive (N1b) disease. Using DRS at follow-up of 1.5 year, pubertal and postpubertal groups showed significantly better response to RAI. More female than male patients showed response and took significantly less time to respond to RAI ( p = 0.003). Conclusion RAI response in pediatric DTC depends on pubertal status, gender, and number of malignant nodes. DRS using RTT classification may be applicable early at 1.5 years after initial therapy in different pubertal age and risk groups.

Fibroblast Activation Protein Inhibitor PET/CT: A Promising Molecular Imaging Tool.

PURPOSE: Fibroblast activation protein (FAP) is a cell membrane-bound serine peptidase, overexpressed in cancer-associated fibroblasts and activated fibroblasts at wound healing/inflammatory sites. Recently, molecular PET/CT imaging with radiolabeled FAP inhibitor (FAPI) has been evaluated in different diseases. We aimed to assess its potential role based on the available literature. PATIENTS AND METHODS: We conducted a comprehensive review of the available preclinical and clinical data on FAPI PET/CT in an attempt to summarize its current status and potential future role. Based on that, we have discussed the pathophysiology behind FAP-based imaging, followed by a discussion of FAPI radiopharmaceuticals including their synthesis, biodistribution, and dosimetry. Next, we have discussed studies evaluating FAPI PET/CT in different oncological and nononcological pathologies. The potential of FAPI PET/CT in theranostics has also been addressed. RESULTS: Based on the early scientific evidence available, including preclinical and clinical studies, FAPI PET/CT seems to be a promising molecular imaging tool, especially in oncology. It can be used for imaging different types of cancers and outperforms 18F-FDG PET/CT in some of these. Its potential as a theranostic tool warrants special attention. CONCLUSIONS: Fibroblast activation protein inhibitor PET/CT has the potential to emerge as a powerful molecular imaging tool in the future. However, as of yet, the available evidence is limited, warranting further research and trials in this field.

Axillary Lymph Nodal Metastases from Thyroid Carcinoma: Report of 2 Cases with Review of Literature.

Thyroid carcinoma has an excellent long-term outcome for locoregional disease if adequately treated, but the outcome declines sharply if distant metastatic disease is present. Axillary lymph nodal metastases are unusual in thyroid carcinoma and have a poorer outcome, as they are usually associated with aggressive histopathologies, extensive locoregional disease, and distant metastatic disease. We report 2 cases of thyroid carcinoma with axillary lymph nodal metastases and their management, and we review the literature on such cases.

Primary Central Nervous System Lymphoma With Diffuse Neurolymphomatosis Involving Multiple Cranial and Spinal Nerve Roots.

Primary central nervous system lymphoma is an extranodal lymphoma originating in the brain, spinal cord, and leptomeninges, which rarely spreads outside the nervous system. Neurolymphomatosis is the term used to describe lymphomatous involvement of the cranial nerves (except optic nerve) and peripheral nerve roots or plexus. We report a case of a 23-year-old man presented with progressive weakness of all 4 limbs. F-FDG PET/CT revealed FDG-avid thickening along the multiple cranial nerve roots, spinal nerve roots, and brain parenchymal lesion. Core biopsy from the peripheral nerve root demonstrated the lymphomatous involvement.

Breast Cancer Imaging With PET Based Radiopharmaceuticals Other Than 18F-FDG.

Breast cancer is the most common cancer in women with rising incidence worldwide. F-FDG PET/CT imaging has already established itself as a pivotal modality for staging, restating and response assessment in patients with carcinoma breast. The complex biology of this cancer is increasingly being decoded and various molecular targets have been identified and exploited for guiding the treatment at various time points during the course of the disease. We here depict a series of various metabolic and receptor targeting PET radiotracers in breast cancer patients which may help us understand the in vivo biology of this tumor.

18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Features in Locally Advanced Breast Cancer and Their Correlation with Molecular Subtypes.

PURPOSE: 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is now recognized as a staging investigation for locally advanced breast cancer. This retrospective review of data was performed to correlate the maximum standardized uptake value (SUVmax) of the primary tumor with the molecular subtype of breast cancer. MATERIALS AND METHODS: Patients with biopsy-proven, treatment naïve, Stage III breast cancer, for whom 18F-FDG PET/CT data and immunohistochemistry 4 was available were included in the study. Correlations were deduced between the SUVmax of primary tumor to the molecular subtypes. RESULTS: Three hundred and two patients were included in the study. Fifty-two (17.2%) tumors were Luminal A (LA), 131 (43.4%) Luminal B (LB), 42 (13.9%) human epidermal growth factor receptor-2 enriched (HE), and 77 (25.5%) basal-like (BL). SUVmax of the primary tumor differed significantly between LA and other subtypes (SUVmax: LA Median 7.4, LB 11.65, HE 13.5, BL 15.35, P < 0.001). Estrogen receptor (ER) and progesterone receptor (PR) positivity were inversely correlated to the SUVmax of the primary (SUVmax: ER + Median 10.4, ER - 14.2, P < 0.001, PR + 9.65, PR - 13.9, P < 0.001). There was a strong positive correlation observed between Ki67 and SUVmax (Pearson Coefficient 0.408, P < 0.001). A SUVmax value of 9.65 was determined as a cutoff on receiver operating characteristic curve to differentiate between LA and other subtypes with a sensitivity of 92.3% and specificity of 70.6%. CONCLUSIONS: SUVmax of primary showed a statistically significant difference between LA subtypes when compared to other subtypes. However, there was overlap of values in each subgroup and thus 18F-FDG PET/CT cannot be used to accurately assess the molecular characteristics of the tumor.