The clinical use of photon-counting CT (PCCT) allows for the generation of virtual non-contrast (VNC) series from contrast-enhanced images. In routine clinical practice, specific issues such as ruling out acute bleeding require non-contrast images. The aim of this study is to evaluate the use of PCCT-derived VNC reconstructions in abdominal imaging. PCCT scans of 17 patients including early arterial, portal venous and native sequences were enrolled. VNC reconstructions have been calculated. In every sequence and VNC reconstruction, 10 ROIs were measured (portal vein, descending aorta, inferior vena cava, liver parenchyma, spleen parenchyma, erector spinae muscle, subcutaneous adipose tissue, first lumbar vertebral body, air, and psoas muscle) and density values were compared. The VNC reconstructions show significant changes in density compared to the contrast-enhanced images. However, there were no significant differences present between the true non-contrast (TNC) and any VNC reconstructions in the observed organs and vessels. Significant differences (p < 0.05) between the measured mean density values in the TNC versus VNC reconstructions were found in fat and bone tissue. The PCCT-derived VNC reconstructions seemed to be comparable to the TNC images, despite some deviations shown in the adipose tissue and bone structures. However, the further benefits in terms of specific clinical issues need to be evaluated.

With personalized tumor therapy, understanding and addressing the heterogeneity of malignant tumors is becoming increasingly important. Heterogeneity can be found within one lesion (intralesional) and between several tumor lesions emerging from one primary tumor (interlesional). The heterogeneous tumor cells may show a different response to treatment due to their biology, which in turn influences the outcome of the affected patients and the choice of therapeutic agents. Therefore, both intra- and interlesional heterogeneity should be addressed at the diagnostic stage. While genetic and biological heterogeneity are important parameters in molecular tumor characterization and in histopathology, they are not yet addressed routinely in medical imaging. This article summarizes the recently established markers for tumor heterogeneity in imaging as well as heterogeneous/mixed response to therapy. Furthermore, a look at emerging markers is given. The ultimate goal of this overview is to provide comprehensive understanding of tumor heterogeneity and its implications for radiology and for communication with interdisciplinary teams in oncology. Key points:

Objectives: To evaluate the potential of Photon counting CT (PCCT) -derived iodine densities and Virtual-Non-Contrast (VNC) reconstructions for the differentiation between adrenal adenomas and adrenal metastases. Materials and methods: This retrospective study enrolled 53 PCCT scans of patients with adrenal lesions (29 adenomas, 24 metastases) including early-arterial (ea) and portal-venous (pv) contrast phase. Iodine maps and VNC reconstructions were calculated from the acquired sequences. Using the measured values, several parameters such as relative enhancement (RE), normalized iodine density (NID), and iodine to VNC ratio (IVR) were calculated. In the acquired image series, iodine maps and VNC reconstructions density values were evaluated (adrenal lesion, ipsilateral adrenal tissue, contralateral adrenal tissue, portal vein, descending aorta, inferior vena cava, subcutaneous adipose tissue, in the first lumbar vertebral body, surrounding air, and in the psoas muscle) and compared. Results: In total, the measured structures showed significant variation in density values due to different contrast phases and reconstructions. VNC reconstructions of portal-venous contrast phase showed significant differences in measured density mean values between adrenal adenomas and adrenal metastases (21.64 HU vs. 28.26 HU, p: 0.027, AUC: 0.68). No significant differences between metastases and adenomas were observed in iodine concentration, RE of ea, NID of ea and pv, as IVR of ea. Significant alterations were observed in RE of pv (p: 0.023, AUC: 0.7) and IVR of pv (pv: 0.029, AUC: 0.69). Conclusion: The recent study shows that PCCT derived VNC reconstructions of portal venous contrast phase can be used for reliable differentiation of adrenal adenomas and adrenal metastases and underlines the value of PCCT in oncological imaging.

Purpose: Hepatocellular carcinoma (HCC) is the largest subgroup of primary liver tumors. Ablative therapies, such as selective internal radiation therapy (SIRT), are used in late stages for patients with unresectable liver metastases and no response to other therapies. CCL2 (C-C motif chemokine ligand 2) is a potent monocyte chemoattractant. It is associated with tumor progression and metastasis. The role of circulating CCL2 as a biomarker in HCC undergoing selective internal radiation therapy remains unclear. Methods: A total of 41 patients (8 female, 33 male) suffering from HCC and undergoing SIRT were enrolled. Pre- and post-therapy changes in circulating CCL2 levels were determined by bead-based immunoassay and compared with clinical laboratory parameters and patient data. Results: A total of 32 patients exhibited survival beyond 60 days. It was observed that levels of CCL2 correlated with scores indicating a higher likelihood of non-survival and with the severity of the disease. Moreover, a significant inverse correlation was discovered between CCL2 levels and the survival of patients over 60 days in relation to counts of leukocytes, granulocytes, monocytes, and C-reactive protein. Conclusions: CCL2 may serve as a potential marker for patient survival after SIRT. The prediction of which HCC patients are likely to benefit from SIRT may be helpful in guiding therapeutic management.

With personalized tumor therapy, understanding and addressing the heterogeneity of malignant tumors is becoming increasingly important. Heterogeneity can be found within one lesion (intralesional) and between several tumor lesions emerging from one primary tumor (interlesional). The heterogeneous tumor cells may show a different response to treatment due to their biology, which in turn influences the outcome of the affected patients and the choice of therapeutic agents. Therefore, both intra- and interlesional heterogeneity should be addressed at the diagnostic stage. While genetic and biological heterogeneity are important parameters in molecular tumor characterization and in histopathology, they are not yet addressed routinely in medical imaging. This article summarizes the recently established markers for tumor heterogeneity in imaging as well as heterogeneous/mixed response to therapy. Furthermore, a look at emerging markers is given. The ultimate goal of this overview is to provide comprehensive understanding of tumor heterogeneity and its implications for radiology and for communication with interdisciplinary teams in oncology.

Die diffuse alveoläre Hämorrhagie (DAH) beschreibt eine Subgruppe der pulmonalen Blutungen. Sie kann bei verschiedenen Grunderkrankungen auftreten und potenziell lebensbedrohlich sein [Reisman S et al. AJR Am J Roentgenol 2021; 216: 1500–1509]. Nach ihrer Genese kann sie in 4 Subgruppen eingeteilt werden: immunassoziiert, assoziiert mit kongestivem Herzversagen, sonstige Ursachen (beispielsweise Infektionen, Trauma oder medikamentös-toxisch) und idiopathisch. Bei den meisten Fällen ist jedoch die Pathogenese unbekannt [Park JA. Int J Mol Sci 2021; 22]. Klinisch präsentieren sich die Patienten mit Atemnot, Hämoptysen und Anämie [Qi Y. et al. Transl Pediatr 2021; 10: 2921–2928]. Zur Diagnostik der DAH gehört eine Bronchoskopie. Diese dient dem Nachweis einer Hämorrhagie in der bronchoalveolären Lavage (BAL), sowie dem Ausschluss von makroskopisch sichtbaren Blutungen [Ioachimescu OC et al. Cleve Clin J Med 2008; 75: 258, 260, 264–5]. Ebenso kann die Projektionsradiografie des Thorax diagnostisch eingesetzt werden. Diese weist typischerweise bipulmonale Konsolidierungen mit zentraler Betonung auf [Reisman S et al. AJR Am J Roentgenol 2021; 216: 1500–1509]. Die Computertomografie (CT) zeigt in der akuten Phase zentral betonte Milchglastrübungen, die in Konsolidierungen übergehen können und Ausdruck einer subtotalen Füllung der Alveolen mit Blut sind. Ebenfalls kann das „dark-bronchus-sign“ vorliegen, welches eine scheinbare Hervorhebung segmentaler und subsegmentaler Bronchien beschreibt. Dabei wirken die luftgefüllten Bronchien durch das umgebende dichteangehobene Lungenparenchym dunkler als in der gesunden Lunge. Innerhalb von 2–3 Tagen kann das „crazy-paving“-Muster auftreten, das durch eine landkartenartige Verteilung von Milchglasarealen mit Überlagerung durch verdickte Intra-, sowie Interlobärsepten gekennzeichnet ist [Marten K et al. AJR Am J Roentgenol 2005; 184]. Betroffene Patienten zeigen hohe Mortalitätsraten und benötigen eine zielgerichtete Therapie. Diese besteht aus supportiven Maßnahmen, der Behandlung der Grunderkrankung (meist durch Immunsuppressiva) und lokaler Hämostase [Park JA. Int J Mol Sci 2021; 22]. Received: 28 September 2022 Accepted after revision: 22 January 2023 Article published online: 02 March 2023 © 2023. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany