The aim of this study was to evaluate the roles of 67Ga-citrate and 99Tcm-methylene diphosphonate (99Tcm-MDP) planar and single photon emission tomographic (SPET) imaging in patients with vertebral osteomyelitis. Thirty patients (22 females, 8 males) aged 62.7 +/- 16.4 years (mean +/- s) were enrolled prospectively between May 1995 and May 1998. The patients had been on antibiotics for 7 +/- 4 weeks prior to the study. Histology was available for all but nine patients with mild infections, who were evaluated by a combination of magnetic resonance imaging (MRI), clinical and laboratory tests. 67Ga-citrate (185 MBq) and three-phase bone (555 MBq 99Tcm-MDP) planar and SPET imaging were performed in all patients, together with MRI as a comparison. In total, 67 infectious foci were detected. Based on histology, there were four cases of severe, 13 cases of moderate and four cases of mild osteomyelitis; nine mild infections were also classified by the combination of MRI, clinical and laboratory results. Combined MRI and 67Ga-citrate SPET correctly classified all patients; MRI detected all 67 infectious foci, whereas 67Ga-citrate SPET identified 54 only. False-negative results were seen with all other modalities, especially in cases of mild and moderate infection. 67Ga-citrate SPET identified unsuspected cases of endocarditis (n = 2), paravertebral abscess (n = 1), subaxillary soft tissue abscess (n = 1) and rib osteomyelitis (n = 1). For 67Ga-citrate SPET, the target-to-background ratio was 2.24 +/- 0.31, 1.76 +/- 0.07 and 1.30 +/- 0.18 for severe, moderate and mild osteomyelitis, respectively. Significant differences were noted between severe and moderate infection (P = 0.0051) and between severe and mild infection (P < 0.0001); that between moderate and mild infection was non-significant. For 99Tcm-MDP planar and SPET imaging, and for planar 67Ga-citrate imaging, there was no correlation with severity. We conclude that 67Ga-citrate SPET is able to identify vertebral osteomyelitis and detect additional sites of infection. It can also aid in determining the severity of infection and, potentially, the response to therapy.

Purpose To assess suspected acute stroke, the computed tomography (CT) protocol contains a non-contrast CT (NCCT), a CT angiography (CTA), and a CT perfusion (CTP). Due to assumably high radiation doses of the complete protocol, the aim of this study is to examine radiation exposure and to establish diagnostic reference levels (DRLs). Methods In this retrospective study, dose data of 921 patients with initial CT imaging for suspected acute stroke and dose monitoring with a DICOM header–based tracking and monitoring software were analyzed. Between June 2017 and January 2020, 1655 CT scans were included, which were performed on three different modern multi-slice CT scanners, including 921 NCCT, 465 CTA, and 269 CTP scans. Radiation exposure was reported for CT dose index (CTDIvol) and dose-length product (DLP). DRLs were set at the 75th percentile of dose distribution. Results DRLs were assessed for each step (CTDIvol/DLP): NCCT 33.9 mGy/527.8 mGy cm and CTA 13.7 mGy/478.3 mGy cm. Radiation exposure of CTP was invariable and depended on CT device and its protocol settings with CTDIvol 124.9–258.2 mGy and DLP 1852.6–3044.3 mGy cm. Conclusion Performing complementary CT techniques such as CTA and CTP for the assessment of acute stroke increases total radiation exposure. Hence, the revised DRLs for the complete protocol are required, where our local DRLs may help as benchmarks.

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F-PSMA-1007 PET is used in the management of patients with prostate cancer. However, recent reports indicate a high rate of unspecific bone uptake (UBU) with 18 F-PSMA-1007, which may lead to a falsepositive diagnosis. UBU has not been evaluated thoroughly. Here, we evaluate the frequency of UBU and bone metastases separately for 18 F-PSMA-1007 and 68 Ga-PSMA-11 in biochemical recurrence (interindividual comparison). Additionally, we investigate UBU seen in 18 F-PSMA-1007 through follow-up examinations (intraindividual comparison) using 68 Ga-PSMA-11 PET, bone scintigraphy, and MRI. Methods: First, all patients (n 5 383) who underwent 68 Ga-PSMA-11 PET between January 2020 and December 2020 and all patients (n 5 409) who underwent 18 F-PSMA-1007 PET between January 2020 and November 2021 due to biochemical recurrence were included for an interindividual comparison of bone metastases and UBU rate. In a second approach, we regarded all patients with UBU in 18 F-PSMA-1007, characterized by focal bone uptake with an SUV max . 4 and prostate-specific antigen (PSA) # 5 ng/mL, who underwent additional 68 Ga-PSMA-11 PET (n 5 17) (interindividual comparison). Of these, 12 patients also had bone scintigraphy and whole-body MRI within a 1-to 5-wk interval. Bone uptake seen on 18 F-PSMA-1007 but not on any of the other 4 modalities (CT, MRI [n 5 1], bone scanning, and 68 Ga-PSMA-11 PET) was recorded as false-positive. Results: Patients scanned with 18 F-PSMA-1007 PET had a significantly higher rate of UBU than those scanned with 68 Ga-PSMA-11 (140 vs. 64; P , 0.001); however, the rate of bone metastases was not significantly different (72 vs. 64; P 5 0.7). In the intraindividual comparison group, workup by CT, MRI, bone scanning, and 68 Ga-PSMA-11 PET resulted in a positive predictive value for 18 F-PSMA-1007 focal bone uptake (mean SUV max , 6.1 6 2.9) per patient and per lesion of 8.3% and 3.6%, respectively. Conclusion: In patients with PSA # 5 ng/mL and SUV . 4 at biochemical recurrence, most 18 F-PSMA-1007 focal bone uptake is likely to be false-positive and therefore due to UBU. In the case of low clinical likelihood of metastatic disease, 18 F-PSMA-1007 bone uptake without morphologic surrogate should be assessed carefully with regard to localization and clinical context. However, the rate of bone metastases was not higher with 18 F-PSMA-1007 in the clinical routine, indicating that experienced reporting physicians adjust for UBU findings.

Purpose The aim of this study was to determine local diagnostic reference levels (DRLs) during endovascular diagnostics and therapy of carotid-cavernous fistulas (CCF). Methods In a retrospective study design, DRLs, achievable dose (AD) and mean values were assessed for all patients with CCF undergoing diagnostic angiography (I) or embolization (II). All procedures were performed with the flat-panel angiography system Allura Xper (Philips Healthcare). Interventional procedures were differentiated according to the type of CCF and the type of procedure. Results In total, 86 neurointerventional procedures of 48 patients with CCF were executed between February 2010 and July 2021. The following DRLs, AD and mean values could be determined: (I) DRL 215 Gy ∙ cm2, AD 169 Gy ∙ cm2, mean 165 Gy ∙ cm2; (II) DRL 350 Gy ∙ cm2, AD 226 Gy ∙ cm2, mean 266 Gy ∙ cm2. Dose levels of embolization were significantly higher compared to diagnostic angiography (p < 0.001). No significant dose difference was observed with respect to the type of fistula or the embolization method. Conclusion This article reports on diagnostic and therapeutic DRLs in the management of CCF that could serve as a benchmark for the national radiation protection authorities. Differentiation by fistula type or embolization method does not seem to be useful.