Diagnostic Value of Dual-Energy CT Virtual Non-Calcium and Rho/Z Images for Bone Marrow Infiltration in Primary Malignant Bone Tumors

Diagnostic efficacy of dual-energy CT virtual non-calcium technique in the diagnosis of bone marrow edema of sacroiliac joints in ankylosing spondylitis

OBJECTIVE

In-depth investigation of the diagnostic performance of dual-energy CT (DECT) virtual non-calcium (VNCa) technique for sacroiliac joint bone marrow edema (BME) in patients with ankylosing spondylitis(AS).

METHODS

A total of 42 patients with AS)who underwent sacroiliac joint MRI and DECT scans on the same day at our Rheumatology and Immunology Department between August 2022 and June 2023 were selected. Using MRI as the reference standard, the presence of BME on the iliac and sacral surfaces was evaluated, resulting in the categorization of patients into BME-positive and BME-negative groups. Subsequently, the DECT scan data was processed using the "Bone Marrow" algorithm to generate VNCa color-coded images of the bone marrow. The diagnostic performance of DECT in detecting BME was assessed through visual qualitative evaluation and objective quantitative analysis.

RESULTS

Visual qualitative assessment analysis showed good agreement between the results of BME analysis on virtual non-calcium images and MRI images by both physicians (Kappa > 0.61). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of visual qualitative assessment for BME by Physicians A and B were as follows: iliac facet [(92.5%, 88.6%, 88.1%, 92.9%, 90.5%), (90.0%, 90.9%, 90.0%, 90.9%, 90.5%)], sacral facet [(88.4%, 87.8%, 88.4%, 87.8%, 88.1%), (90.7%, 85.3%, 86.7%, 89.7%, 88.1%)].In terms of objective quantitative analysis, the CT values of the edematous areas on the iliac and sacral surfaces were (-41.4 ± 15.9) Hu and (-38.8 ± 19.7) Hu, respectively, while the CT values of normal bone marrow areas were (-79.6 ± 18.2) Hu and (-72.8 ± 14.8) Hu, respectively. The CT values of the edematous areas were higher than those of the non-edematous areas. Based on the receiver operating characteristic curve analysis, the area under the curve for the iliac and sacral surfaces were 0.90 and 0.89, respectively. The optimal CT cutoff values were - 57.4 Hu and - 56.8 Hu, with corresponding sensitivities of 92.5% and 86.4% and specificities of 90.7% and 87.8%.

CONCLUSION

The DECT VNCa technique has a high diagnostic efficacy in the diagnosis of BME in the sacroiliac joints in ankylosing spondylitis in terms of visual qualitative assessment and objective quantitative analysis.

Quantitative multi-energy CT in oncology: State of the art and future directions

Multi-energy computed tomography (CT) involves acquisition of two or more CT measurements with distinct energy spectra. Using the differential attenuation of tissues and materials at different X-ray energies, multi-energy CT allows distinction of tissues and materials. Multi-energy technology encompasses different types of CT systems, such as dual-energy CT and photon-counting CT, that can use information from the energy and type of material present in acquired images to create multiple datasets. These scanners have overcome many of the limitations of conventional CT, making it possible to improve the diagnostic performance of CT and expand its use to new applications through better tissue characterization and multiple quantitative parameters. Quantitative imaging biomarkers based on multi-energy CT have enormous potential in oncologic imaging, from the diagnosis and characterization of tumor phenotypes to the evaluation of the response to treatment. Nevertheless, implementing these techniques in clinical practice remains challenging. This article reviews the basic principles underlying multi-energy CT and the most recent technical developments in these systems together with their advantages and limitations to establish the value of quantitative imaging derived from multi-energy CT in the field of oncology.

Electron density dual-energy CT can improve the detection of lumbar disc herniation with higher image quality than standard and virtual non-calcium images

OBJECTIVES

To compare the diagnostic performance and image quality of dual-energy computed tomography (DECT) with electron density (ED) image reconstruction with those of DECT with standard CT (SC) and virtual non-calcium (VNCa) image reconstructions, for diagnosing lumbar disc herniation (L-HIVD).

METHODS

A total of 59 patients (354 intervertebral discs from T12/L1 to L5/S1; mean age, 60 years; 30 women and 29 men) who underwent DECT with spectral reconstruction and 3-T MRI within 2 weeks were enrolled between March 2021 and February 2022. Four radiologists independently assessed three image sets of randomized ED, SC, and VNCa images to detect L-HIVD at 8-week intervals. The coefficient of variance (CV) and the Weber contrast of the ROIs in the normal and diseased disc to cerebrospinal fluid space (NCR-normal/-diseased, respectively) were calculated to compare the image qualities of the noiseless ED and other series.

RESULTS

Overall, 129 L-HIVDs were noted on MRI. In the detection of L-HIVD, ED showed a higher AUC and sensitivity than SC and VNCa; 0.871 vs 0.807 vs 833 (p = 0.002) and 81% vs 70% vs 74% (p = 0.006 for SC), respectively. CV was much lower in all measurements of ED than those for SC and VNCa (p < 0.001). Furthermore, NCR-normal and NCR-diseased were the highest in ED (ED vs SC in NCR-normal and NCR-diseased, p =  0.001 and p = 0.004, respectively; ED vs VNCa in NCR-diseased, p = 0.044).

CONCLUSION

Compared to SC and VNCa images, DECT with ED reconstruction can enhance the AUC and sensitivity of L-HIVD detection with a lower CV and higher NCR.

CLINICAL RELEVANCE STATEMENT

To our knowledge, this is the first study to quantify the image quality of noiseless ED images. ED imaging may be helpful for detecting L-HIVD in patients who cannot undergo MRI.

KEY POINTS

ED images have diagnostic potential, but relevant quantitative analyses of image quality are limited. ED images detect disc herniation, with a better coefficient of variance and normalized contrast ratio values. ED images could detect L-HIVD when MRI is not an option.

Diagnostic Value of Dual-Energy CT Virtual Noncalcium for the Assessment of Bone Marrow Edema of Wrist in Patients with Rheumatoid Arthritis

RATIONALE AND OBJECTIVES

To evaluate the value of dual-energy CT (DECT) virtual noncalcium (VNCa) images in the diagnosis of wrist bone marrow edema (BME) in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

43 patients with wrist involvement in active RA prospectively underwent DECT and MRI. Functional DECT images reconstruction yielded VNCa images. MRI served as the reference standard for diagnosing BME. BME diagnosis differences between VNCa images and MRI were compared. Differences in CT values between BME and normal bone marrow were assessed. The optimal CT value for detecting BME in VNCa images was determined through ROC curve analysis. The correlation between VNCa images scores and RA disease activity was evaluated.

RESULTS

There was a high agreement between VNCa images and MRI in diagnosing BME (Kappa=0.831). VNCa images showed a significant difference in CT values between BME and normal bone marrow (P < 0.001). A cut-off value of - 54.8 HU yielded a sensitivity, specificity, and accuracy of 90.72%, 94.30%, and 93.33%, respectively, for detecting BME on VNCa images. The area under the ROC curve was 0.937 for distinguishing BME from normal bone marrow. Conventional CT images showed no statistically significant difference (P = 0.174) in CT values between BME and normal bone marrow. The VNCa images BME scores were positively correlated with RA disease activity (r = 0.399).

CONCLUSION

The DECT VNCa technique demonstrates its potential for diagnosing wrist BME in patients with RA and provides a valuable tool for assessing disease activity in RA.

IMPORTANT FINDINGS

The DECT VNCa technique has the ability to distinguish between BME and normal bone marrow. The VNCa images BME scores were positively correlated with the disease activity in RA.

Role of effective atomic number of paraspinal muscles in the prediction of acute vertebral fracture risk assessment: a cross-sectional case-control study

OBJECTIVES

We aim to investigate the relations among effective atomic number (Zeff), density, and area of paraspinal muscles, volumetric bone mineral density (vBMD), and acute vertebral fractures (VF) by using spectral base images (SBIs) and routine CT images.

METHODS

A total of 223 patients (52 men and 171 women) with acute lumber VF and 776 subjects (286 men and 390 women) without VF of at least 60 years were enrolled and underwent dual-layer detector CT scans. We quantified the cross-sectional area, density (paraSMD), and Zeff of paraspinal muscles by CT images and SBIs and measured vBMD of the lumbar spine by quantitative CT.

RESULTS

Higher vBMD was associated with lower VF risk in both sexes (adjusted OR, 0.33 and 0.43). After adjusting for age and body mass index, the associations of paraSMD with VF were not significant in men, and in women the association was borderline significant (OR, 0.80; 95% CI, 0.64-1.00). However, higher Zeff of paraspinal muscles was associated with lower VF risk in men (adjusted OR, 0.59; 0.36-0.96) but not in women. The associations of all muscle indexes with VF were not significant after further adjusting for vBMD.

CONCLUSIONS

A higher Zeff of paraspinal muscles is associated with lower VF risk in older men but not in older women. The density, area, and Zeff of paraspinal muscles were not vBMD independent risk factors for acute VF.

ADVANCES IN KNOWLEDGE

The effective atomic number of paraspinal muscles might be a potential marker for VF risk prediction.

Updates on the Applications of Spectral Computed Tomography for Musculoskeletal Imaging

Spectral CT represents a novel imaging approach that can noninvasively visualize, quantify, and characterize many musculoskeletal pathologies. This modality has revolutionized the field of radiology by capturing CT attenuation data across multiple energy levels and offering superior tissue characterization while potentially minimizing radiation exposure compared to traditional enhanced CT scans. Despite MRI being the preferred imaging method for many musculoskeletal conditions, it is not viable for some patients. Moreover, this technique is time-consuming, costly, and has limited availability in many healthcare settings. Thus, spectral CT has a considerable role in improving the diagnosis, characterization, and treatment of gout, inflammatory arthropathies, degenerative disc disease, osteoporosis, occult fractures, malignancies, ligamentous injuries, and other bone-marrow pathologies. This comprehensive review will delve into the diverse capabilities of dual-energy CT, a subset of spectral CT, in addressing these musculoskeletal conditions and explore potential future avenues for its integration into clinical practice.