Diagnostic value of spectral reconstructions in detecting incidental skeletal muscle metastases in CT staging examinations

Simon Lennartz; Nils Große Hokamp; Nuran Abdullayev; Markus Le Blanc; Andra-Iza Iuga; Grischa Bratke; David Zopfs; David Maintz; Jan Borggrefe; Thorsten Persigehl

doi:10.1186/s40644-019-0235-3

Diagnostic value of spectral reconstructions in detecting incidental skeletal muscle metastases in CT staging examinations

Cancer Imaging. 2019 Jul 17;19(1):50. doi: 10.1186/s40644-019-0235-3.

Authors

Affiliations

¹ Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
² Else Kröner Forschungskolleg Clonal Evolution in Cancer, University Hospital Cologne, Weyertal 115b, 50931, Cologne, Germany.
³ Department of Radiology, Case Western Reserve University and University Hospitals, Cleveland, OH, USA.
⁴ Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Str. 62, 50937, Cologne, Germany. thorsten.persigehl@uk-koeln.de.

Abstract

Background: To investigate if iodine density overlay maps (IDO) and virtual monoenergetic images at 40 keV (VMI_40keV) acquired from spectral detector computed tomography (SDCT) can improve detection of incidental skeletal muscle metastases in whole-body CT staging examinations compared to conventional images.

Methods: In total, 40 consecutive cancer patients who underwent clinically-indicated, contrast-enhanced, oncologic staging SDCT were included at this retrospective study: 16 patients with n = 108 skeletal muscle metastases confirmed by prior or follow-up CT, ¹⁸F-FDG-PET, MRI or histopathology, and a control group of 24 patients without metastases. Four independent readers performed blinded, randomized visual detection of skeletal muscle metastases in conventional images, IDO and VMI_40keV, indicating diagnostic certainty for each lesion on a 5-point Likert scale. Quantitatively, ROI-based measurements of attenuation (HU) in conventional images and VMI_40keV and iodine concentration in IDO were conducted. CNR was calculated and receiver operating characteristics (ROC) analysis of quantitative parameters was performed.

Results: Regarding subjective assessment, IDO (63.2 (58.5-67.8) %) and VMI_40keV (54.4 (49.6-59.2) %) showed an increased sensitivity for skeletal muscle metastases compared to conventional images (39.8 (35.2-44.6) %). Specificity was comparable in VMI_40keV (69.8 (63.2-75.8) %) and conventional images (69.2 (60.6-76.9) %), while in IDO, it was moderately increased to 74.2 (65.3-78.4) %. Quantitative image analysis revealed that CNR of skeletal muscle metastases to circumjacent muscle was more than doubled in VMI_40keV (25.8 ± 11.1) compared to conventional images (10.0 ± 5.3, p ≤ 0.001). Iodine concentration obtained from IDO and HU acquired from VMI_40kev (AUC = 0.98 each) were superior to HU attenuation in conventional images (AUC = 0.94) regarding differentiation between healthy and metastatic muscular tissue (p ≤ 0.05).

Conclusions: IDO and VMI_40keV provided by SDCT improve diagnostic accuracy in the assessment of incidental skeletal muscle metastases compared to conventional CT.

Keywords: Dual energy computed tomography; Iodine maps; Iodine quantification; Oncologic imaging; Skeletal muscle metastases.

Publication types

Evaluation Study

MeSH terms

Adult
Aged
Female
Humans
Iodine Radioisotopes
Male
Middle Aged
Muscle Neoplasms / diagnostic imaging*
Muscle Neoplasms / secondary
Muscle, Skeletal / diagnostic imaging*
Muscle, Skeletal / pathology
Radiopharmaceuticals
Tomography, X-Ray Computed / methods*
Tomography, X-Ray Computed / standards

Substances

Iodine Radioisotopes
Radiopharmaceuticals