Accuracy of Dopamine Transporter Imaging with 123I-Ioflupane in Hispanic and Non-Hispanic Patients.

Racial and ethnic disparities in the prevalence of neurodegenerative diseases exist. This study examined the agreement between gold standard diagnosis and visual assessment of dopamine transporter (DaT) imaging in Hispanic and non-Hispanic patients being evaluated for Parkinsonian syndromes (PS). Methods: A retrospective review of DaT imaging and demographic data was performed with institutional review board approval. Documented interpretation by visual assessment was used to classify scans as normal or abnormal. The gold standard for the final diagnosis of PS was determined by a neurologist after 2 or more years of clinical follow-up. Data were analyzed with a z-test for uncorrelated samples. Results: In 30 Hispanic patients, DaT imaging was abnormal in 17, normal in 12, and nondiagnostic in 1. Of those with abnormal imaging, PS was confirmed in 16 of 17. Of those with normal imaging, no PS was confirmed in any patient. Sensitivity was 100%, and specificity was 92%. The single patient with nondiagnostic imaging was excluded. Of 77 non-Hispanic patients, visual assessment of DaT imaging was abnormal in 51. Of those with abnormal imaging, PS was confirmed in 48 of 51. Of those with normal imaging, no PS was confirmed in 22 of 26. Sensitivity was 92%, and specificity was 88%. There was no statistically significant difference (z = 0.34) in the rates of agreement between the gold standard and DaT imaging in Hispanic versus non-Hispanic patients. The study sample size afforded a power of 0.60. Conclusion: No significant difference was found in the accuracy of DaT imaging between Hispanic and non-Hispanic patients. Accuracy was high for both groups.

Signs and Artifacts in Amyloid PET.

Establishing a diagnosis of Alzheimer dementia can be challenging, particularly early in the course of the disease. However, with disease-modifying therapies on the horizon, it is becoming increasingly important to achieve the correct diagnosis as soon as possible. In challenging presentations of dementia, such as patients with clinically atypical features or early-age onset of mild cognitive impairment, amyloid PET is a valuable tool in determining the diagnosis of Alzheimer dementia. Furthermore, preliminary data show that amyloid PET findings alter clinical management in patients who meet the appropriate use criteria. There are currently three U.S. Food and Drug Administration (FDA)-approved fluorine 18 (18F)-labeled radiopharmaceuticals that allow in vivo detection of cerebral amyloid deposition, which is a hallmark pathologic feature of Alzheimer dementia. Knowledge of the common imaging features among these three 18F-labeled radiopharmaceuticals in the normal and abnormal brain will enable the radiologist to more accurately interpret amyloid PET studies. As in other subspecialties of radiology, imaging signs in amyloid PET are helpful to distinguish if a region is normal or abnormal. This article reviews appropriate use criteria for amyloid PET, introduces the properties of the radiopharmaceuticals, explains the algorithmic approach to interpretation with examples of normal and abnormal amyloid PET scans with MRI correlation, and provides an atlas of regional amyloid PET signs and common artifacts. ©RSNA, 2018.

18F-FDG PET/CT for Monitoring Response of Merkel Cell Carcinoma to the Novel Programmed Cell Death Ligand 1 Inhibitor Avelumab.

An 85-year-old man with stage IIIA Merkel cell carcinoma of the left arm was initially treated with local excision and axillary node dissection followed by radiation therapy. Eight months after surgery, whole-body FDG PET/CT demonstrated intensely hypermetabolic hepatic metastases and abdominal lymphadenopathy. Given his age and comorbidities, he was considered a poor candidate for chemotherapy, and therefore the novel programmed cell death ligand 1 inhibitor avelumab was initiated. FDG PET/CT after 4 cycles showed complete resolution of hepatic and nodal metastases. Whole-body FDG PET/CT can be used for monitoring response of multisystem metastases from Merkel cell carcinoma to active immunotherapy.

Dynamic Adaptation of Tumor Immune Response With Nivolumab Demonstrated by 18F-FDG PET/CT.

A 61-year-old woman with lung adenocarcinoma failed first-line treatment and was placed on immunotherapy with nivolumab. FDG-PET/CT before immunotherapy showed metastases to thoracic nodes, liver, adrenal gland, and skeleton. Seven weeks after starting nivolumab, FDG-PET/CT showed mild residual activity in thoracic nodes and otherwise complete response. After 15 weeks, enlarged and FDG-avid axillary lymphadenopathy and worsening supraclavicular lymphadenopathy developed. After 20 weeks, FDG-PET/CT demonstrated marked improvement of axillary and supraclavicular lymphadenopathy. This case demonstrates that later progression of disease can still respond to continuing immunotherapy, hypothetically because of dynamic adaptations in the tug-of-war between the immunotherapy-augmented immune system and tumor.

Artifactual Hepatic Metastasis on FDG PET/CT Secondary to Cryoablation for Adrenal Metastasis.

A 65-year-old woman with metastatic lung cancer was referred for CT-guided cryoablation of a right adrenal metastasis. For cryoablation, probes were placed into the adrenal region. FDG PET/CT 3 months later showed new activity in hepatic segment 6 initially suspected to be metastasis. Proximity of the hepatic lesion to the adrenal metastasis was a strange coincidence and prompted review of imaging from the cryoablation. CT showed the probe entered the liver, and postablation image demonstrated injury to the liver adjacent to the adrenal metastasis. Careful review of treatment history and imaging from ablation procedures are important to avoid this pitfall.

Signaling pathways induced by a tumor-derived vaccine in antigen presenting cells.

We have previously reported on the anti-tumoral potential of a chaperone-rich cell lysate (CRCL) vaccine. Immunization with CRCL generated from tumors elicits specific T and NK cell-dependent immune responses leading to protective immunity in numerous mouse tumor models. CRCL provides both a source of tumor antigens and danger signals leading to dendritic cell activation. In humans, tumor-derived CRCL induces dendritic cell activation and CRCL-loaded dendritic cells promote the generation of cytotoxic T lymphocytes in vitro. The current study was designed to identify the signaling events and modifications triggered by CRCL in antigen presenting cells. Our results indicate that tumor-derived CRCL not only promotes the activation of dendritic cells, but also significantly fosters the function of macrophages that thus appear as major targets of this vaccine. Activation of both cell types is associated with the induction of the MAP kinase pathway, the phosphorylation of STAT1, STAT5 and AKT and with transcription factor NF-kappaB activation in vitro and in vivo. These results thus provide important insights into the mechanisms by which CRCL-based vaccines exert their adjuvant effects on antigen presenting cells.

Imatinib mesylate inhibits CD4+ CD25+ regulatory T cell activity and enhances active immunotherapy against BCR-ABL- tumors.

Imatinib mesylate (Gleevec, STI571), a selective inhibitor of a restricted number of tyrosine kinases, has been effectively used for the treatment of Philadelphia chromosome-positive leukemias and gastrointestinal stromal tumors. Imatinib may also directly influence immune cells. Suppressive as well as stimulating effects of this drug on CD4(+) and CD8(+) T lymphocytes or dendritic cells have been reported. In the current study, we have investigated the influence of imatinib mesylate on CD4(+)CD25(+)FoxP3(+) regulatory T cells (Treg), a critical population of lymphocytes that contributes to peripheral tolerance. Used at concentrations achieved clinically, imatinib impaired Treg immunosuppressive function and FoxP3 expression but not production of IL-10 and TGF-beta in vitro. Imatinib significantly reduced the activation of the transcription factors STAT3 and STAT5 in Treg. Analysis of Treg TCR-induced signaling cascade indicated that imatinib inhibited phosphorylation of ZAP70 and LAT. Substantiating these observations, imatinib treatment of mice decreased Treg frequency and impaired their immunosuppressive function in vivo. Furthermore, imatinib mesylate significantly enhanced antitumor immune responses to dendritic cell-based immunization against an imatinib-resistant BCR-ABL negative lymphoma. The clinical applications of imatinib mesylate might thus be expanded with its use as a potent immunomodulatory agent targeting Treg in cancer immunotherapy.

Characterization of high-salt and high-fat diets on cardiac and vascular function in mice.

This study compared two established dietary formulations, high salt and high fat-high carbohydrate, separately or in combination on the induction cardiovascular dysfunction. One-month-old C57BL/6J mice were fed one of the following diets for 3 mo: (1) control diet consisting of a high fat-high sim-ple carbohydrate (HFHSC); (2) 8% NaCl diet (HS); or (3) HFHSC diet supplemented with 1% NaCl (HFHS). After 3 mo, the HFHSC mice demonstrated significantly increased end-diastolic volume and end-systolic volume, specifically increases of 35% and 78%, respectively (p < 0.01) and a reduction of ventricular stiffness by 27% (p = 0.015). The HS mice exhibited arterial hyper-tension with an increase of 33% in maximum end-systolic pressure (p =.024) and a decrease of 44% in arterial elastance (p = 0.020), corroborated by an increase in the heart weight to body weight ratios (p = 0.002) and vascular types I and III collagen (p = 0.03 and p = 0.0008, respectively). The HFHS group revealed a striking response of 230% to the alpha1-adrenergic challenge (p = 0.00034). These data suggest that the HFHSC diet causes dilated cardio-myopathy, whereas the HS diet produces arterial hypertension and the HFHS diet causes a vascular dysfunctional state that was highly responsive to alpha-adrenergic stimulation.