Optimal conspicuity of pancreatic ductal adenocarcinoma in virtual monochromatic imaging reconstructions on a photon-counting detector CT: comparison to conventional MDCT.

PURPOSE: To analyze the conspicuity of pancreatic ductal adenocarcinoma (PDAC) in virtual monoenergetic images (VMI) on a novel photon-counting detector CT (PCD-CT) in comparison to energy-integrating CT (EID-CT). METHODS: Inclusion criteria comprised initial diagnosis of PDAC (reference standard: histopathological analysis) and standardized contrast-enhanced CT imaging either on an EID-CT or a PCD-CT. Patients were excluded due to different histopathological diagnosis or missing tumor delineation on CT. On the PCD-CT, 40-190 keV VMI reconstructions were generated. Image noise, tumor-to-pancreas ratio (TPR) and contrast-to-noise ratio (CNR) were analyzed by ROI-based measurements in arterial and portal venous contrast phase. Two board-certified radiologist evaluated image quality and tumor delineation at both, EID-CT and PCD-CT (40 and 70 keV). RESULTS: Thirty-eight patients (mean age 70.4 years ± 10.3 [range 45-91], 27 males; PCD-CT: n=19, EID-CT: n=19) were retrospectively included. On the PCD-CT, tumor conspicuity (reflected by low TPR and high CNR) was significantly improved at low-energy VMI series (≤ 70 keV compared to > 70 keV), both in arterial and in portal venous contrast phase (P < 0.001), reaching the maximum at 40 keV. Comparison between PCD-CT and EID-CT showed significantly higher CNR on the PCD-CT in portal venous contrast phase at < 70 keV (P < 0.016). On the PCD-CT, tumor conspicuity was improved in portal venous contrast phase compared to arterial contrast phase especially at the lower end of the VMI spectrum (≤ 70 keV). Qualitative analysis revealed that tumor delineation is improved in 40 keV reconstructions compared to 70 keV reconstructions on a PCD-CT. CONCLUSION: PCD-CT VMI reconstructions (≤ 70 keV) showed significantly improved conspicuity of PDAC in quantitative and qualitative analysis in both, arterial and portal venous contrast phase, compared to EID-CT, which may be important for early detection of tumor tissue in clinical routine. Tumor delineation was superior in portal venous contrast phase compared to arterial contrast phase.

Plain X-ray is insufficient for correct diagnosis of tibial shaft spiral fractures: a prospective trial.

PURPOSE: Tibial shaft spiral fractures and fractures of the distal third of the tibia (AO:42A/B/C and 43A) frequently occur with non-displaced posterior malleolus fractures (PM). This study investigated the hypothesis that plain X-ray is not sufficient for a reliable diagnosis of associated non-displaced PM fractures in tibial shaft spiral fractures. METHODS: 50 X-rays showing 42A/B/C and 43A fractures were evaluated by two groups of physicians, each group was comprised of a resident and a fellowship-trained traumatologist or radiologist. Each group was tasked to make a diagnosis and/or suggest if further imaging was needed. One group was primed with the incidence of PM fractures and asked to explicitly assess the PM. RESULTS: Overall, 9.13/25 (SD ± 5.77) PM fractures were diagnosed on X-ray. If the posterior malleolus fracture was named or a CT was requested, the fracture was considered "detected". With this in mind, 14.8 ± 5.95 posterior malleolus fractures were detected. Significantly more fractures were diagnosed/detected (14 vs. 4.25/25; p < 0.001/14.8 vs. 10.5/25; p < 0.001) in the group with awareness. However, there were significantly more false positives in the awareness group (2.5 vs. 0.5; p = 0.024). Senior physicians recognized slightly more fractures than residents (residents: 13.0 ± 7.79; senior physicians: 16.5 ± 3.70; p = 0.040). No significant differences were demonstrated between radiologists and trauma surgeons. The inner-rater reliability was high with 91.2% agreement. Inter-rater reliability showed fair agreement (Fleiss-Kappa 0.274, p < 0.001) across all examiners and moderate agreement (Fleiss-Kappa 0.561, p < 0.001) in group 2. CONCLUSION: Only 17% of PM fractures were identified on plain X-ray and awareness of PM only improved diagnosis by 39%. While experiencing improved accuracy, CT imaging should be included in a comprehensive examination of tibial shaft spiral fractures. LEVEL OF EVIDENCE: II. Diagnostic prospective cohort study. TRAIL REGISTRATION NUMBER: DRKS00030075.

[Radiologic evaluation of lymph nodes in cancer patients]. / Bildgebende Diagnostik von Lymphknoten bei Verdacht auf Tumorbefall.

BACKGROUND: In solid tumors, the detection of locoregional lymph node metastases is of decisive importance not only for the prognosis but also for selecting the correct treatment. Various noninvasive imaging methods or, classically, lymph node dissection are available for this purpose. OBJECTIVE: This article presents the general principles of noninvasive lymph node diagnostics and discusses the value of the clinically available imaging modalities, ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). In addition, recent new technical developments of each modality are highlighted. MATERIAL AND METHODS: Literature search and summary of the clinical and scientific experience of the authors. RESULTS: The available imaging procedures are divided into (1) morphological (US, CT, MRI) and (2) functional modalities (PET, special MRI). The former capture structural lymph node parameters, such as size and shape, while the latter address properties that go beyond morphology (e.g. glucose metabolism). The high diagnostic accuracy required for future treatment algorithms will require a combination of both aspects. DISCUSSION/CONCLUSION: Currently, none of the available modalities have sufficient accuracy to replace lymph node dissection in all oncological scenarios. One of the major challenges for interdisciplinary oncological research is to define the optimal interaction between imaging and lymph node dissection for different malignancies and tumor stages.