Can Radiomics Provide Additional Information in [18F]FET-Negative Gliomas?

The purpose of this study was to evaluate the possibility of extracting relevant information from radiomic features even in apparently [18F]FET-negative gliomas. A total of 46 patients with a newly diagnosed, histologically verified glioma that was visually classified as [18F]FET-negative were included. Tumor volumes were defined using routine T2/FLAIR MRI data and applied to extract information from dynamic [18F]FET PET data, i.e., early and late tumor-to-background (TBR5-15, TBR20-40) and time-to-peak (TTP) images. Radiomic features of healthy background were calculated from the tumor volume of interest mirrored in the contralateral hemisphere. The ability to distinguish tumors from healthy tissue was assessed using the Wilcoxon test and logistic regression. A total of 5, 15, and 69% of features derived from TBR20-40, TBR5-15, and TTP images, respectively, were significantly different. A high number of significantly different TTP features was even found in isometabolic gliomas (after exclusion of photopenic gliomas) with visually normal [18F]FET uptake in static images. However, the differences did not reach satisfactory predictability for machine-learning-based identification of tumor tissue. In conclusion, radiomic features derived from dynamic [18F]FET PET data may extract additional information even in [18F]FET-negative gliomas, which should be investigated in larger cohorts and correlated with histological and outcome features in future studies.

An 82-year-old man with a prosthetic aortic valve and multimicrobial bacteremia.

The patient is an 82-year-old male with a past medical history of aortic valve replacement who presented to the emergency department after a fall. He developed atrial fibrillation with a rapid ventricular response and non-ST-segment-elevation myocardial infarction, leading to hospitalization. During hospital admission, the patient complained of midline thoracic back pain, and an extensive evaluation for this complaint revealed discitis and osteomyelitis with epidural abscess near the T7 and T8 vertebrae that did not result in neurological deficits and required no surgical intervention. A total of 2 blood cultures were reported positive for Actinomyces naeslundii, Streptococcus mitis, Streptococcus oralis, and Abiotrophia defectiva. A transesophageal echocardiogram showed a small vegetation on the aortic prosthetic valve with probable small vegetation on the mitral valve. He was prescribed ceftriaxone intravenously for 12 weeks, followed by amoxicillin 2 g orally twice a day for at least 12 months. A. naeslundii is not commonly known to cause infective endocarditis, whereas S. mitis, S. oralis, and A. defectiva have been reported to do so. One previous case of A. naeslundii was reported to cause prosthetic valve endocarditis as a single infectious agent. To our knowledge, this is the first case report for A. naeslundii as part of multimicrobial bacteremia leading to endocarditis, discitis, and osteomyelitis.

Metastatic Osseous Disease Masquerading as Infection, Diagnosed on Bone Scintigraphy and SPECT/CT.

We present a 72-y-old woman with an osseous metastasis to the spine that had an atypical appearance on both nuclear medicine and radiologic modalities and was misdiagnosed as an abscess. We discuss the pitfalls of bone scintigraphy and the causes of photopenic metastatic lesions.

Acute Hematogenous Osteomyelitis Presenting as a "Cold" Rib in a Child.

A "cold" defect or an area of decreased radiotracer deposition is the less common appearance of acute hematogenous osteomyelitis (AHO) on a Tc99 m-methylene disphosphonate (Tc99 m-MDP) bone scan. Group A beta-hemolytic Streptococcus (GABHS) is a significantly less common cause of AHO than Staphylococcus aureus, particularly when the infection involves the pelvis or flat bones such as the ribs. Here, we present a case report of isolated acute "cold" hematogenous osteomyelitis in a rib of a child with GABHS bacteremia that was detected on 99Tc-MDP bone scan, with magnetic resonance imaging correlation, and pathologic confirmation after rib resection.

Vertebral hemangioma: "Cold" vertebrae on bone scintigraphy and fluordeoxy-glucose positron emission tomography-computed tomography.

Bone hemangiomas are benign and infrequent lesions. At Tc-99m bone scintigraphy they show variable degrees of radiotracer uptake and even absence of it. At fluordeoxy-glucose (FDG) Positron Emission Tomography-Computed Tomography (PET/CT), hemangioma is one of the causes of "cold" vertebrae, apart from postexternal radiotherapy. We present a woman diagnosed of breast carcinoma, with a photopenic defect at a thoracic vertebrae at Tc-99m bone scan. In order to rule out bone lytic metastasis, a FDG PET/CT was performed showing a "cold" vertebrae too. Findings were highly suggestive of vertebral hemangioma, that was confirmed by magnetic resonance imaging.