RPS 1416 - Latest CT technology in oncologic imaging

Author Block: M. Dimitrova, A. Gökduman, V. Koch, L. D. Gruenewald, L. S. Alizadeh, S. Martin, T. J. Vogl, I. Yel, C. Booz; Frankfurt/DE
Purpose: This study aims to evaluate the diagnostic accuracy of dual-energy computed tomography (DECT)-based Rho/Z-maps for differentiation of hypodense liver lesions in patients with diagnosed colorectal carcinoma compared with conventional CT value measurements.
Methods or Background: This retrospective study included 364 patients (mean age, 70 ± 13 years; 183 men and 181 women) suffering from colorectal carcinoma who had undergone third-generation dual-source DECT as part of tumour staging between January 2016 and January 2023. For this study, we measured Rho (electron density) and Z (effective atomic number) values as well as Hounsfield units (HU) in hypodense liver lesions. Values were compared, and diagnostic accuracy for differentiation was computed using receiver operating characteristic (ROC) curve analyses. MRI or biopsy served as a standard of reference for lesion characterisation.
Results or Findings: A total of 822 lesions (351 metastases and 471 cysts) in contrast-enhanced DECT images were evaluated. Mean Rho, Z and HU120kV values showed significant differences between both liver lesion types (p<.0001). The greatest difference between measured values for liver metastases and benign cysts was observed for Rho (MD, -35.31 ± 3.217, 92%; HU120kV MD, -21.46 ± 3.017, 60%). Rho and Z measurements showed a higher AUC value (Rho, 0.962; 95% CI, 0.936-0.989; Z, 0.918; 95% CI, 0.845-0.954) compared with HU120kV (0.802; 95% CI, 0.741-0.862) for lesion differentiation.
Conclusion: Rho and Z measurements derived from DECT allow for improved differentiation of liver metastases and cysts in patients with colorectal carcinoma compared with conventional CT value measurements.
Limitations: The single-centre retrospective study design was an identified limitation.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the local IRB.

Author Block: H. Blomstrand¹, W. C. Bartholomä¹, E. Tesselaar¹, B. Björnsson¹, T. Bjerner¹, M. Sandborg¹, N. Elander², M. Woisetschlager¹; ¹Linköping/SE, ²Liverpool/UK
Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a challenging condition with low survival rates. Accurate imaging is vital for treatment decisions. Photon-counting CT (PCCT) is an emerging technology with potential benefits over standard CT. This pilot study assessed PCCT's usefulness in pancreatic and PDAC imaging compared to energy-integrating detector (EID) CT.
Methods or Background: Eight PDAC patients received equivalent radiation doses of EID and PCCT scans, with five experienced evaluators rating image quality using a Likert scale. Quantitative measures including contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), noise levels, and tissue sharpness (line density profiles) were also recorded.
Results or Findings: PCCT images matched EID CT quality overall, with a slight preference for EID CT in arterial phase images for three parameters (p=0.015). Venous phase image quality showed no significant difference (p>0.05). Quantitatively, PCCT displayed a trend toward higher CNR and SNR, indicating potential advantages in tissue differentiation. Noise levels were lower in PCCT images, especially in pancreatic tissue (p=0.064). Line density profiles hinted at sharper tissue edges in PCCT, although not statistically significant.
Conclusion: In conclusion, this pilot study suggests that PCCT is a promising imaging tool for pancreatic cancer patients. Despite slight preferences for EID CT in certain criteria, PCCT's quantitative advantages and noise reduction trends indicate its potential for enhancing soft tissue discrimination and clinical outcomes, pending further advancements in PCCT technology.
These findings suggest PCCT's promise in pancreatic imaging, offering similar image quality to EID CT. Quantitative assessments hint at potential benefits in tissue differentiation and noise reduction. While EID CT was preferred in some criteria, PCCT's advantages may improve with evolving technology.
Limitations: This is a pilot study with a low number of patients. Comparison was made only to one scanner (Somatom Force).
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Swedish Ethical Review Authority.

Author Block: H. Watanabe, Y. Sato, K. Oikado, T. Terauchi; Tokyo/JP
Purpose: The fifth edition of the WHO classification introduced a grading system for invasive non-mucinous adenocarcinoma. Lesions are categorised into Grade 1 (well-differentiated), Grade 2 (moderately differentiated), and Grade 3 (poorly differentiated) based on the percentage of histological subtypes with a high-risk pattern for poor prognosis. This study investigates the correlation between the iodine concentration (IC) of lung adenocarcinoma measured by dual-energy CT (DECT) and this WHO grading.
Methods or Background: We examined preoperative contrast DECTs from 111 patients (46 men, 65 women; median age: 70 years; 37 Grade 1, 25 Grade 2, 49 Grade 3) diagnosed with primary lung adenocarcinoma between January and December 2022. Cases with a solid component diameter under 5 mm on CT or those with invasive mucinous adenocarcinoma were excluded. IC measurements were taken during the equilibrium phase, 3 minutes after contrast administration. The corrected IC was determined by dividing the IC in the solid component of the lesion by the IC in the descending aorta at the tracheal bifurcation level. An ordinal logistic regression model, accounting for corrected IC, smoking status, nodule type (solid or part-solid), gender, and age, was employed for the multiple regression analysis.
Results or Findings: The multivariable analysis identified that significant independent predictors for a higher grade of invasive non-mucinous adenocarcinoma were the corrected IC (OR, 2.74 [95% CI, 1.46–5.98]; p = .005) and the presence of a pure solid nodule (OR, 5.02 [95% CI, 2.21-11.8]; p<.001).
Conclusion: IC measurements using DECT may predict the grade of pulmonary invasive non-mucinous adenocarcinoma.
Limitations: This study's limitations include its single-centre focus and retrospective design.
Funding for this study: This study was financially supported by Bayer Pharma Japan.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The institutional review board approved this study, and there was a waiver for the need for written informed consent.

Author Block: T. Lee¹, J-H. Yoon¹, J. Park², J. Lee¹, J. W. Choi¹, C. Ahn¹, J-M. Lee¹; ¹Seoul/KR, ²Busan/KR
Purpose: The study aimed to investigate the diagnostic value of low-contrast-dose liver CT using a deep learning-based iodine contrast-augmenting algorithm (DLICA) to assess hypovascular hepatic metastases.
Methods or Background: This retrospective study included 128 patients who underwent contrast-enhanced DECT for hepatic metastasis surveillance between July 2019 and June 2022 using a 30% reduced iodine contrast dose in the portal phase. Three image types were reconstructed: 50-keV virtual monoenergetic images (50-keV VMI); linearly blended images simulating 120-kVp images (120-kVp); and post-processed 120-kVp images using DLICA (DLICA 120-kVp). Three reviewers evaluated lesion conspicuity, and contrast-to-noise ratios (CNRs) were measured from the regions of interest in the metastatic lesions and liver parenchyma. The detection performance for hepatic metastases was evaluated using a jackknife alternative free-response receiver operating characteristic method, with the consensus of two independent radiologists as the reference standard.
Results or Findings: DLICA 120-kVp demonstrated significantly higher CNR of lesions to liver (5.7±3.1 vs. 3.8±2.1 vs. 3.8±2.1) and superior lesion conspicuity (4.0[3.3–4.3] vs. 3.7[3.0–4.0] vs. 3.7[3.0–4.0]) compared with 50-keV VMI and 120-kVp (P<0.001 for all). Although there was no significant difference of merit in the figure for lesion detection among the three methods (P=0.105), DLICA 120-kVp had a significantly higher figure of merit for lesions with a diameter <20 mm than 50-keV VMI (0.677 vs. 0.648, P=0.007). DLICA 120-kVp also demonstrated higher sensitivity on a per-lesion basis than the 50-keV VMI (81.2% vs. 72.9%, P<0.001).
Conclusion: DLICA 120-kVp provided higher lesion conspicuity and similar diagnostic performance to detect hypovascular hepatic metastases compared with 50 keV VMI. DLICA 120-kVp can serve as an alternative to 50keV VMI for improved detection of liver metastases, particularly in the case of smaller lesions, circumventing the need for high-end DECT equipment.
Limitations: The retrospective study design and the small sample size were identified limitations.
Funding for this study: This study was supported by a research grant from ClariPi (No. 06-2022-4530).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This retrospective study was approved by the Institutional Review Board of Seou National University Hospital and the requirement for written informed consent was waived.

Author Block: T. Xie, W. Liu, W. Deng, Y. Wang, W. Tang, Z. Zhou; Shanghai/CN
Purpose: The study aimed to investigate the value of dual-layer spectral-detector CT (DLCT) in detecting neuroendocrine tumour liver metastases (NETLM) and to compare the diagnostic performance of polyenergetic CT images (PEI), DLCT, and Gd-EOB-DTPA-enhanced MR.
Methods or Background: Seventy-two patients with suspected NETLM who underwent both DLCT and Gd-EOB-DTPA-enhanced MR within three weeks were retrospectively enrolled, and they were divided into dataset 1 and dataset 2. In dataset 1, virtual monoenergetic images (VMI) at 40-140 keV (VMI40-140, 10-keV interval) were reconstructed. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of NETLM were measured and compared between PEI and VMIs. In dataset 2, two readers independently evaluated the diagnostic performance of PEI (Set 1), VMI + PEI (Set 2), and Gd-EOB-DTPA-enhanced MR (Set 3) for detecting NETLM. Subgroup analysis stratified by lesion size was performed.
Results or Findings: In dataset 1, VMI40 exhibited highest SNR and CNR across all energy levels, which was significantly higher than that of PEI (P<0.01). In dataset 2, a total of 477 lesions were identified (396 metastases, 81 benign lesions). Adding VMI40 into PEI resulted in a significantly improved per-lesion AUC and sensitivity (AUC, Set 1: 0.85; Set 2: 0.90, P < 0.01; Sensitivity, Set 1: 0.76; Set 2: 0.86, P < 0.01). Set 3 achieved the highest per-lesion AUC of 0.97 and per-lesion sensitivity of 0.95. Subgroup analysis demonstrated that the difference in diagnostic performance was concentrated on lesions <10 mm.
Conclusion: Gd-EOB-DTPA-enhanced MR yielded the highest diagnostic accuracy for NETLM detection. DLCT should be an alternative choice, given the superior image quality and incremental diagnostic value of VMI40.
Limitations: The retrospective study design introduces the potential risk of selection bias.
Funding for this study: Funding was received from the Hong Kong, Macao, and Taiwan Cooperation Project of Scientific and Innovative Plan of Shanghai (22490760800).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This retrospective study was approved by the Institutional Review Board of the Fudan University Shanghai Cancer Center (1612167–18). Informed consent was waived owing to the retrospective nature of the study.

Author Block: F. Haag¹, N. Große Hokamp², D. P. Overhoff¹, G. Dasegowda³, A. Hertel¹, D. Nörenberg¹, S. O. Schönberg¹, M. K. Kalra³, M. Frölich¹; ¹Mannheim/DE, ²Cologne/DE, ³Boston, MA/US
Purpose: The use of port implants in cancer patients during follow-up CT scans can result in beam hardening artefacts, which can significantly impact the quality and accuracy of the acquired images. The aim of this study is to improve image quality and accuracy in thoracic imaging using photon-counting computed tomography (PCCT) derived spectral reconstructions.
Methods or Background: This retrospective single-centre study enrolled 49 patients with port systems undergoing CT for staging of oncologic disease. 8 ROIs for 19 spectral reconstructions (polyenergetic imaging, monoenergetic reconstructions from 40 to 190 keV [in steps of 10] as well as iodine maps and virtual non contrast [VNC]) were measured, resulting in a total of 7,448 mean and SD Hounsfield unit measurements of port-chamber associated hypo- and hyperdense artefacts, bilateral muscles and vessels. Additionally, a subjective analysis of the degree of artefacts was performed in consensus reading by two radiologists with more than 25 years and more than 5 years of experience in thoracic imaging.
Results or Findings: In quantitative analysis, a significant association of keV and iodine contrast as well as artefact intensity was noted (p<0.001). In qualitative assessment, utilisation of 120 keV monoenergetic reconstructions could reduce severe and pronounced artefacts completely, when compared to lower keV reconstructions (p<0.001). For imaging findings, no significant difference between monoenergetic reconstructions could be noted (all p>0.05).
Conclusion: PCCT-derived, monoenergetic CT reconstructions are capable of reducing beam-hardening artefacts in chest imaging. They may prove helpful to improve diagnostic confidence in these cases.
Limitations: The present study deals mainly with the potential of spectral reconstructions for artefact suppression. Other algorithms for artefact reduction were not investigated and could be the subject of further research.
Funding for this study: This research was funded by the Photon-counting Consortium Baden-Württemberg (PC3), BMBF-Research Campus M2OLIE and Hector Foundation, as well as a travel grant from ICON (DFG).
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: No information provided by the submitter.