Detection of Bone Marrow Edema Pattern With Dual-Energy Computed Tomography of the Pig Mandible Treated With Radiotherapy and Surgery Compared With Magnetic Resonance Imaging:

Dual-energy CT-derived virtual noncalcium imaging to assess bone marrow lesions in patients with knee osteoarthritis

To determine the diagnostic performance of dual-energy CT (DECT) virtual noncalcium (VNCa) technique in the detection of bone marrow lesions (BMLs) in knee osteoarthritis, and further analyze the correlation between the severity of BMLs on VNCa image and the degree of knee pain. 23 consecutive patients with clinically diagnosed knee osteoarthritis were underwent DECT and 3.0T MRI between August 2017 and November 2018. Evaluation of two pain assessment scales (WOMAC and KOOS) were collected. VNCa images and MRI were independently scored by three readers using a four-level scoring system over 15 anatomical subregions in each knee joint. Spearman correlation coefficient was used for total BML scores on DECT and MRI correlation with WOMAC and KOOS. Specificity, Sensitivity, NPV and PPV of reader 1 and reader 2 were 99.4%/99.2%, 89.4%/87.2%, 98.6%/98.3% and 95.5%/93.2%. A cutoff value of - 41.5 HU/- 46.5 HU provided sensitivities of 93.2%/90.9% and specificities of 100.0%/93.9% for diagnosing BMLs with AUC of 0.970/0.996. A stronger correlation was observed between the WOMAC and total BML score compared to the KOOS. DECT possessed excellent diagnostic performance in the detection of BMLs in knee osteoarthritis. And the pain degree increased with the severity of BMLs on VNCa images.

Characterization of size-specific effects during dual-energy CT material decomposition of non-iodine materials

PURPOSE

The dual-energy CT (DECT) LiverVNC application class in the Siemens Syngo.via software has been used to perform non-iodine material decompositions. However, the LiverVNC application is designed with an optional size-specific calibration based on iodine measurements. This work investigates the effects of this iodine-based size-specific calibration on non-iodine material decomposition and benchmarks alternative methods for size-specific calibrations.

METHODS

Calcium quantification was performed with split-filter and sequential-scanning DECT techniques on the Siemens SOMATOM Definition Edge CT scanner. Images were acquired of the Gammex MECT abdomen and head phantom containing calcium inserts with concentrations ranging from 50-300 mgCa/ml. Several workflows were explored investigating the effects of size-specific dual-energy ratios (DERs) and the beam hardening correction (BHC) function in the LiverVNC application. Effects of image noise were also investigated by varying CTDIvol and using iterative reconstruction (ADMIRE).

RESULTS

With the default BHC activated, Syngo.via underestimated the calcium concentrations in the abdomen for sequential-scanning acquisitions, leaving residual calcium in the virtual non-contrast images and underestimating calcium in the enhancement images for all DERs. Activation of the BHC with split-filter images resulted in a calcium over- or underestimation depending on the DER. With the BHC inactivated, the use of a single DER led to an under- or overestimate of calcium concentration depending on phantom size and DECT modality. Optimal results were found with BHC inactivated using size-specific DERs. CTDIvol levels and ADMIRE had no significant effect on results.

CONCLUSION

When performing non-iodine material decomposition in the LiverVNC application class, it is important to understand the implications of the BHC function and to account for patient size appropriately. The BHC in the LiverVNC application is specific to iodine and leads to inaccurate quantification of other materials. The inaccuracies can be overcome by deactivating the BHC function and using size-specific DERs, which provided the most accurate calcium quantification.

Advanced CT and MR Imaging of the Posttreatment Head and Neck

Advances in MR and computed tomography (CT) techniques have resulted in greater fidelity in the assessment of treatment response and residual tumor on one hand and the assessment of recurrent head and neck malignancies on the other hand. The advances in MR techniques primarily are related to diffusion and perfusion imaging which rely on the intrinsic architecture of the tissues and organ systems. The techniques exploit the density of the cellular architecture; and the vascularity of benign and malignant lesions which in turn affect the changes in the passage of contrast through the vascular bed. Dual-energy CT and CT perfusion are the major advances in CT techniques that have found significant applications in the assessment of treatment response and tumor recurrence.

Single-source dual-energy computed tomography for the detection of bone marrow lesions: impact of iterative reconstruction and algorithms

PURPOSE

To compare the diagnostic performance of different reconstruction algorithms of single-source dual-energy computed tomography (DECT) for the detection of bone marrow lesions (BML) in patients with vertebral compression fracture using MRI as the standard of reference.

MATERIAL AND METHODS

Seventeen patients with an age over 50 who underwent single-source DECT of the spine were included. The raw data (RD) were reconstructed using filtered back-projection (FBP) and iterative reconstruction (IR) with three iteration levels (IR1-IR3). Bone marrow images were generated using a three-material decomposition (3MD) and a two-material decomposition (2MD) algorithm and an RD-based approach. Three blinded readers scored the images for image quality and the presence of bone marrow lesions (BML). Only vertebrae with height loss were included. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The different reconstructions were compared using Dunn's multiple comparison test.

RESULTS

Thirty-nine vertebrae were included. IR(1-3) showed superior sensitivity (87.5%) compared to FBP (75%) using 3MD but was comparable to RD (83.3%). All 2MD images were inferior (sensitivity < 38%). The image quality score was significantly higher for 3MD-IR(1-3) compared to 3MD-FBP (p < 0.0001) and all 2MD data sets (p < 0.03). This pattern was also supported by the SNR and CNR measurements. RD showed no significant improvement compared to IR.

CONCLUSION

The image quality of bone marrow images acquired with DECT can be improved by using IR compared with FBP. RD-based reconstruction does not offer significant improvement over image data-based reconstruction. 2MD algorithms are not suitable for BML detection.

Clinical application of multi-material artifact reduction (MMAR) technique in Revolution CT to reduce metallic dental artifacts

Background

This study aimed to explore the performance of Revolution CT virtual monoenergetic images (VMI) combined with the multi-material artifact reduction (MMAR) technique in reducing metal artifacts in oral and maxillofacial imaging.

Results

There were significant differences in image quality scores between VMI + MMAR images and VMI+MARS (multiple artifact reduction system) images at each monochromatic energy level (p = 0.000). Compared with the MARS technology, the MMAR technology further reduced metal artifacts and improved the image quality. At VMI_{90 keV} and VMI_{110 keV}, the SD, CNR, and AI in the Revolution CT group were significantly lower than in the Discovery CT, but no significant differences in these parameters were found between two groups at VMI_{50 keV}, VMI_{70 keV}, and VMI_{130 keV} (p > 0.05). The attenuation was comparable between two groups at any energy level (p > 0.05).

Conclusions

Compared with the MARS reconstruction technique of Discovery CT, the MMAR technique of Revolution CT is better to reduce the artifacts of dental implants in oral and maxillofacial imaging, which improves the image quality and the diagnostic value of surrounding soft tissues.

Utility of CT and MRI in assessment of mandibular involvement in oral cavity cancer

Objective

Oral cavity squamous cell carcinoma (SCC) may present with early invasion of mandibular bone. Preoperative planning of surgery is essential considering patient's postoperative quality of life. Our purpose was to evaluate the efficacy of computer tomography scan (CT) and magnetic resonance imaging (MRI) in detecting mandibular bone involvement in oral SCC.

Methods

A retrospective study was conducted on 98 patients with SCC of floor of mouth, lower alveolus and retromolar trigone operated on with curative intent. Preoperative CT and MRI scans were re-reviewed by a consultant radiologist and original histology slides were re-reviewed by 3 pathologists.

Results

Forty-five patients were included in the final study. Combined CT and MRI had a sensitivity of 100% and a specificity of 72%.

Conclusion

The results suggest that combined CT and MRI have diagnostic utility in detecting mandibular invasion by oral cancer, but with a significant false positive rate.

Dual-Energy CT in Head and Neck Imaging

PURPOSE OF REVIEW

To explain the technique of Dual-energy CT (DECT) and highlight its applications and advantages in head and neck radiology.

RECENT FINDINGS

Using DECT, additional datasets can be created next to conventional images. In head and neck radiology, three material decomposition algorithms can be used for improved lesion detection and delineation of the tumor. Iodine concentration measurements can aid in differentiating malignant from nonmalignant lymph nodes and benign posttreatment changes from tumor recurrence. Virtual non-calcium images can be used for detection of bone marrow edema. Virtual mono-energetic imaging can be useful for improved iodine conspicuity at lower keV and for reduction of metallic artifacts and increase in signal-to-noise ratio at higher keV.

SUMMARY

DECT and its additional reconstructions can play an important role in head and neck cancer patients, from initial diagnosis and staging, to therapy planning, evaluation of treatment response and follow-up. Moreover, it can be helpful in imaging of infections and inflammation and parathyroid imaging as supplementary reconstructions can be obtained at lower or equal radiation dose compared with conventional single energy scanning.