Metabolic tumor volume (MTV) on interim-PET (I-PET) is a potential prognostic biomarker for diffuse large B-cell lymphoma (DLBCL). Implementation of MTV on I-PET requires consensus which semiautomated segmentation method delineates lesions most successfully with least user interaction.Methods used for baseline PET are not necessarily optimal for I-PET due to lower lesional standardized uptake values (SUV) at I-PET. Therefore, we aimed to evaluate which method provides the best delineation quality of Deauville-score (DS) 4-5 DLBCL lesions on I-PET at best interobserver agreement on delineation quality and, secondly, to assess the effect of lesional SUVmax on delineation quality and performance agreements. Methods: DS4-5 lesions from 45 I-PET scans were delineated using six semiautomated methods i) SUV 2.5, ii) SUV 4.0, iii) adaptive threshold [A50%peak], iv) 41% of maximum SUV [41%max], v) majority vote including voxels detected by ≥2 methods [MV2] and vi) detected by ≥3 methods [MV3]. Delineation quality per MTV was rated by three independent observers as acceptable or non-acceptable. For each method, observer scores on delineation quality, specific agreements and MTV were assessed for all lesions, and per category of lesional SUVmax (<5, 5-10, >10). Results: In 60 DS4-5 lesions on I-PET, MV3 performed best, with acceptable delineation in 90% of lesions, with a positive agreement (PA) of 93%. Delineation quality scores and agreements per method strongly depended on lesional SUV: the best delineation quality scores were obtained using MV3 in lesions with SUVmax<10 and SUV4.0 in more FDG-avid lesions. Consequently, overall delineation quality and PA improved by applying the most preferred method per SUV category instead of using MV3 as single best method. MV3-and SUV4.0-derived MTVs of lesions with SUVmax>10, were comparable after excluding visually failed MV3 contouring. For lesions with SUVmax<10, MTVs using different methods correlated poorly. Conclusion: On I-PET, MV3 performed best and provided the highest interobserver agreement regarding acceptable delineations of DS4-5 DLBCL lesions. However, delineation method preference strongly depended on lesional SUV. Therefore, we suggest to explore an approach that identifies the optimal delineation method per lesion as function of tumor FDG uptake characteristics, i.e. SUVmax.

Background During the current pandemic, there is an increased incidence of neurologic/neuropsychiatric manifestations in patients with the novel coronavirus (COVID-19). Neurologic manifestations may be coincident or result of disease and its therapy. In the emergency department, orientation of the clinician with this issue is crucial for accurate decision making to limit the spread of infection during neurologic treatment. This study aimed to be familiar with MRI findings in patients with Neuro-COVID. Seventy patients presented with neurologic/neuropsychiatric manifestation either post COVID or during hospitalization underwent cerebral MRI from April 2020 to June 2021 (39 men and 31women; mean age 43.27, age range from 16 to 69 years). Results Headache (80%), is the most prevalent neurological manifestations followed by smell and taste impairment (62.9%) and stroke symptoms (45.7%). Low mood and anxiety (17.1%), prolonged fatigue (14.3%) and depression (7.1%) are the most common psychiatric symptoms. Infarctions, hematoma and demyelinating disease are the most prevalent findings. There is a week positive correlation between MRI findings and CT chest finding but without statistical significance (P-value 0.2). Conclusions Cerebrovascular disease and demyelinating lesions are common manifestations of COVID 19. Familiarity of neurologists and radiologist in the emergency department and in-patient with this issue is crucial to avoid misdiagnosis and the spread of infection.

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Background PET/CT is a well-established tool in the diagnostic workup of oncology patients. With the advance in diagnosis and therapy of oncology patients, survivors are at risk of developing additional malignancies. This study aimed to evaluate the yield of 18F-FDG PET/CT in biopsy guidance for the detection of unexpected additional primary malignancies in patients with known primary cancers. Medical records of patients underwent 18F-FDG PET/CT scans from July 2015 to December 2017 were reviewed, and 644 patients (346 men and 298 women; mean age 59.7, age range from 21: 78) who had been scanned for known cancers were included in this study. Lesions that were newly detected on PET/CT had not been previously detected by other modalities and were atypical in location for metastases were interpreted as suggestive of a new primary malignant tumor. These image findings guide the biopsy for histopathology, immune-histochemistry to confirm the diagnosis. Results PET-positive findings suggestive of new primary malignant tumors were found in 30 (4.67%) of 644 patients. In 21 (3.26%) of 644 patients, these lesions were pathologically proven to be malignant (20 true positive and 1 case false negative). Proven sites were lung (5 cases), colorectal (5 cases), breast (2 case), liver (2 cases), head and neck (2 cases), anal (1 cases), gastric (1 case), lymphoma (1 case), esophagus (1 case), and prostate (1 case). In 9/30 (30%) patients suspected to have additional primary, PET was falsely positive. Biopsy was taken for histology and immune-histochemistry with follow-up record that confirms the diagnosis to validate the PET/CT findings. Conclusions With the use of 18-F FDG PET/CT image- guided biopsy, additional primary malignancies were detected in at least 3.26% of oncology patients; thus, patient cure is possible if such malignancies are treated promptly and aggressively.

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