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PET-MRI combines positron emission tomography (PET) and magnetic resonance imaging (MRI) into one imaging system. Positron emission tomography–magnetic resonance imaging (PET-MRI) is a hybrid imaging technology that incorporates magnetic resonance imaging soft tissue morphological imaging and positron emission tomography functional imaging.
(A) 57-year-old woman with right upper arm melanoma who received the first dose of the COVID-19 vaccine (Pfizer-BioNTech) in the left deltoid 15 days prior to FDG PET/CT. FDG uptake is observed within left axillary lymph nodes (arrow, SUVmax = 9.3).
(B) 62-year-old man with metastatic prostate carcinoma who received the second dose of COVID-19 vaccine (Pfizer-BioNTech) in the right deltoid 7 days prior to 11C-choline PET/CT. 11C-choline uptake is observed within right axillary lymph nodes (arrows, SUVmax = 3.1) as well as the right deltoid muscle (circle, SUVmax = 1.7).
After radiosurgery concurrent with nivolumab in 59-year-old patient with melanoma BM (patient 1; Supplemental Tables 3 and 5), F-18 FET PET at follow-up 12 weeks after treatment initiation (bottom row) shows significant decrease of metabolic activity (TBRmean, ?28%) compared with baseline (top row), although MRI changes were consistent with progression according to iRANO criteria. Reduction of metabolic activity was associated with stable clinical course over 10 mo. CE = contrast-enhanced. Image created by N. Galldiks et al., Research Center Juelich, Juelich, Germany.
CXCR4-directed PET correlates with MRI-determined lymphoma lesions. Depicted are representative MR images (T1c- and FLAIR- sequences), and the corresponding CXCR4- directed PET images and fusion images (MRI-FLAIR and PET), of two patients with PCNSL and SCNSL, respectively. Images created by Department of Nuclear Medicine, School of Medicine, Technische Universität München, Munich, Germany.
Pre-treatment (A-C) and post-treatment (D-F) images after eight cycles of systemic FOLFIRINOX and consolidative chemoradiation. Baseline CA 19-9 was 145 U/ml. Pre-treatment whole body axial fused PET/MRI showed FDG avid lesion in body of pancreas (arrow, A) with SUVmax 7.1 and SUVgluc 8.0. Lesion was hypo-enhancing on axial contrast-enhanced T1-weighted (T1W) MR image (arrow, B) from focused abdominal PET/MRI and on CT (arrow, C). Pre-treatment CT tumor volume was 10.3 cm3. Post-treatment whole body axial fused PET/MRI showed complete metabolic response (arrow D) with SUVmax 1.9 and SUVgluc 1.9. Lesion was indistinct on axial contrast-enhanced T1W MRI (arrow, E) and CT (arrow, F), and there was upstream pancreatic parenchymal atrophy. Post-treatment CT tumor volume was 0.46 cm3. There was normalization of CA 19-9. Relative change in SUVmax (ΔSUVgluc) was -73%, and relative change in SUVgluc (ΔSUVgluc) was -76%. Based on change in tumor size, response was categorized as partial response per RECIST. Relative change in tumor volume (ΔTvol) was -96%. Pathology showed major pathologic response (College of American Pathologists score 1.) Images courtesy of American Roentgen Ray Society (ARRS), American Journal of Roentgenology (AJR)
Indeterminate lesion on PET/CT classified by PET/MRI for 53-y-old man with lung cancer. Contrast-enhanced CT (A), PET (B), and fused 18F-FDG PET/CT (C) images are displayed in comparison with contrast-enhanced T1-weighted MRI (D), PET, and fused 18F-FDG PET/MRI (F) images. In CT (A), hyperdense, subcentimeter liver lesion (arrows) in segment VII is suggestive of transient hepatic attenuation difference or small hemangioma. As malignancy cannot be excluded, it needs further investigation. On PET/MRI, lesion is clearly classified as metastasis because of contrast enhancement and tracer uptake due to later acquisition time point. Follow-up CT confirmed diagnosis after 78 d. Images created by Ole Martin, University Dusseldorf, Medical Faculty and Benedikt Schaarschmidt, University Hospital Essen.
Adult male with decades of right neck pain, discomfort and tightening following birth injury. The patient had failed multiple standard therapeutic maneuvers before presenting for 18F-FDG PET/MR imaging. Images shows abnormally elevated FDG uptake (white arrows; SUVmax = 1.2) observed in a linear pattern in the space in the posterolateral right neck, between the oblique capitis inferior and the semispinalis capitis muscles, where the greater occipital nerve resides. By comparison, the same region on the contralateral, asymptomatic side of the neck has an SUVmax = 0.7. This result encouraged a surgeon to explore the area. The surgeon ultimately found a collection of small arteries wrapped around the nerve in this location. The small arteries underwent lysis by the surgeon and the patient reported tremendous relief of symptoms. (A) Coronal thick slab MIP of 18F-FDG PET. (B) Axial LAVA FLEX MRI through the cervical spine. (C) Axial PET at the same slice as the axial MRI. (D) Fused axial PET/MRI. Image courtesy of Cipriano, et al., Stanford University, CA.
A 50-y-old postmenopausal woman with fibroadenoma (arrows) in left breast. (A) Unenhanced fat-saturated T1-weighted MRI shows extreme amount of FGT (ACR d). (B) Moderate BPE is seen on dynamic contrast-enhanced MRI at 90 s. (C) Mean ADC of breast parenchyma of contralateral breast on diffusion-weighted imaging with ADC mapping is 1.5 × 10?3 mm2/s. (D) On 18F-FDG PET/CT, lesion is not 18F-FDG-avid, and BPU of normal breast parenchyma is relatively high, with SUVmax of 3.2. Photo courtesy of K Pinker, et al., Medical University of Vienna, Vienna, Austria