Improved differentiation between high- and low-grade gliomas by combining dual-energy CT analysis and perfusion CT

Characterization of Normal Bone in the Equine Distal Limb with Effective Atomic Number and Electron Density Determined with Single-Source Dual Energy and Detector-Based Spectral Computed Tomography

Single-source dual energy (SSDECT) and detector-based spectral computed tomography (DBSCT) are emerging technologies allowing the interrogation of materials that have different attenuation properties at different energies. Both technologies enable the calculation of effective atomic number (EAN), an index to determine tissue composition, and electron density (ED), which is assumed to be associated with cellularity in tissues. In the present prospective observational study, EAN and ED values were determined for 16 zones in normal subchondral and trabecular bone of 37 equine cadaver limbs. Using both technologies, the following findings were obtained: 1. palmar/plantar EAN zone values in the fetlock increased significantly with increasing age of the horse; 2. all EAN and ED values were significantly lower in the trabecular bone than in the subchondral bone of all phalanges; 3. in the distal phalanx and navicular bone, most EAN and ED values were significantly lower compared to the proximal and middle phalanx; and 4. some EAN and ED values were significantly different between front and hind limbs. Several EAN and ED values significantly differed between SSDECT and DBSCT. The reported EAN and ED values in the subchondral and trabecular bone of the equine distal limb may serve as preliminary reference values and aid future evaluation and classification of diseases.

[Usefulness of Electron Density Calculated from Dual Energy CT in Differential Diagnosis between Hepatocellular Carcinoma and Hepatic Hemangioma]

PURPOSE

The aim of this study were to compare electron density (ED), obtained by dual energy computed tomography (DECT), between hepatocellular carcinoma (HCC) and hemangioma, and to assess the differential diagnostic performance of ED between HCC and hemangioma.

METHODS

A total of 46 patients (27 men and 19 women; mean age, 65.7±14.0 years) diagnosed with HCC or hemangioma who underwent upper abdominal DECT between October 2021 and December 2022 were included. ED of each lesion was measured. Relative ED (rED), which is normalized by the ED of background liver parenchyma, was calculated. ED and rED of HCC and hemangioma were statistically analyzed.

RESULTS

The HCC group showed significantly higher ED (48.1±5.2) and rED (80.0±7.3) than the hemangioma group (43.7±4.1, 69.7±7.2, respectively) (p<0.01). The area under the curve of rED was greater than that of ED, but no significant difference was found (p=0.153).

CONCLUSION

ED may help in the differential diagnosis between HCC and hemangioma.

Extracellular volume by dual-energy CT, hepatic reserve capacity scoring, CT volumetry, and transient elastography for estimating liver fibrosis

Our purpose was to compare the efficacy of liver and splenic volumetry (LV and SV), extracellular volume (ECV) on dual-layer spectral-detector CT scoring systems for estimating liver fibrosis (LF) in 45 patients with pathologically staged LF. ECV measured on CT value (HU-ECV), iodine density (ID-ECV), atomic number (Zeff-ECV), and electron density (ED-ECV), LV or SV/body surface area (BSA), albumin bilirubin grade (ALBI), model for end-stage liver disease (MELD) score, aspartate aminotransferase platelet ratio index (APRI), and fibrosis index based on the four factors (FIB-4) were recorded. Transient elastography was measured in 22 patients, and compared to ECV. No correlation was found between transient elastography and all ECVs. Area under the curve (AUC) for estimating F4 on transient elastography was 0.885 (95% CI 0.745-1.000). ALBI was weakly associated with LF (p = 0.451), while MELD (p < 0.001), APRI (p = 0.010), and FIB-4 (p = 0.010) were significantly associated with LF. SV/BSA had a higher AUC than MELD, APRI, and FIB-4 for estimating F4 (AUC = 0.815, 95% CI 0.63-0.999), but MELD (AUC = 0.799, 95% CI 0.634-0.965), APRI (AUC = 0.722, 95% CI 0.561-0.883), and FIB-4 (AUC = 0.741, 95% CI 0.582-0.899) had higher AUCs than ALBI. SV/BSA significantly contributed to differentiation for estimating F4; odds ratio (OR) was 1.304-1.353 (Reader 1-2; R1-R2), whereas MELD significantly contributed to the differentiation between F0-2 and F3-4; OR was 1.528-1.509 (R1-R2). AUC for SV/BSA and MELD combined was 0.877 (95% CI 0.748-1.000). In conclusion, SV/BSA allows for a higher estimation of liver cirrhosis (F4). MELD is more suitable for assessing severe LF (≥ F3-4). The combination of SV/BSA and MELD had a higher AUC than SV/BSA alone for liver cirrhosis (F4).

Spectral CT in Emergency

Spectral CT technology is based on the acquisition of CT images with X-ray at 2 different energy levels which makes possible to distinguish between materials with different atomic numbers using their energy-dependent attenuation, even if those materials have similar density at conventional CT. This kind of technology has gained wide application due to the innumerable uses of their post-processing techniques, including virtual non-contrast images, iodine maps, virtual mono-chromatic images or mixed images without increasing radiation dose. There are several applications of spectral CT in Emergency Radiology that help in the detection, diagnosis and management of various pathologies such as differentiate haemorrhage from the underlaying causative lesion, diagnosis of pulmonary embolisms, demarcation of abscess, characterization of renal stones or reduction of artifacts. The purpose of this review is to provide the emergency radiologist a brief description of the main indications for spectral CT.

Using quantitative parameters derived from pretreatment dual-energy computed tomography to predict histopathologic features in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) patients with a high tumor grade, lymphovascular invasion (LVI), or perineural invasion (PNI) tend to demonstrate a poor prognosis in clinical series. Thus, the identification of histopathological features, including tumor grade, LVI, and PNI, before treatment could be used to stratify the prognosis of patients with HNSCC. This study aimed to assess whether quantitative parameters derived from pretreatment dual-energy computed tomography (DECT) can predict the histopathological features of patients with HNSCC.

METHODS

In this study, 72 consecutive patients with pathologically confirmed HNSCC were enrolled and underwent dual-phase (noncontrast-enhanced phase and contrast-enhanced phase) DECT examinations. Normalized iodine concentration (NIC), the slope of the spectral Hounsfield unit curve (λ_HU), and normalized effective atomic number (NZ_eff) were calculated. The attenuation values on 40-140 keV noise-optimized virtual monoenergetic images [VMIs (+)] in the contrast-enhanced phase were recorded. The diagnostic performance of the quantitative parameters for predicting histopathological features, including tumor grade, LVI, and PNI, was assessed by receiver operating characteristic curves.

RESULTS

The NIC, λ_HU, NZ_eff, and attenuation value on the VMIs (+) at 40 keV (A₄₀) in the grade III group, LVI-positive group, and PNI-positive group were significantly higher than those in the grade I and II groups, the LVI-negative group, and the PNI-negative group (all P values <0.05). A multivariate logistic regression model combining these 4 quantitative parameters improved the diagnostic performance of the model in predicting tumor grade, LVI, and PNI (areas under the curve: 0.969, 0.944, and 0.931, respectively).

CONCLUSIONS

Quantitative parameters derived from pretreatment DECT, including NIC, λ_HU, NZ_eff, and A_4,0 were found to be imaging markers for predicting the histopathological characteristics of HNSCC. Combining all these characteristics improved the predictive performance of the model.

Perfusion CT detects alterations in local cerebral flow of glioma related to IDH, MGMT and TERT status

BACKGROUND

The aim of this study was to investigate the relationship between tumor biology and values of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), time to peak (TTP), permeability surface (PS) of tumor in patients with glioma.

METHODS

Forty-six patients with glioma were involved in the study. Histopathologic and molecular pathology diagnoses were obtained by tumor resection, and all patients accepted perfusion computed tomography (PCT) before operation. Regions of interests were placed manually at tumor and contralateral normal-appearing thalamus. The parameters of tumor were divided by those of contralateral normal-appearing thalamus to normalize at tumor (relative [r] CBV, rCBF, rMTT, rTTP, rPS). The relationships of the parameters, world health organization (WHO) grade, molecular pathological findings were analysed.

RESULTS

The rCBV, rMTT and rPS of patients are positively related to the pathological classification (P < 0.05). The values of rCBV and rPS in IDH mutated patients were lower than those IDH wild-type. The values of rCBF in patients with MGMT methylation were lower than those MGMT unmethylation (P < 0.05). The MVD of TERT wild-type group was lower than TERT mutated group (P < 0.05). The values of rCBV were significant difference in the four molecular groups divided by the combined IDH/TERT classification (P < 0.05). The progression free survival (PFS) and overall survival (OS) were significant difference in the four molecular groups divided by the combined IDH/TERT classification (P < 0.05).

CONCLUSIONS

Our study introduces and supports the changes of glioma flow perfusion may be closely related to its biological characteristics.

Correlation of dual energy computed tomography electron density measurements with cerebral glioma grade

OBJECTIVE

To correlate dual energy computed tomography electron density measurements with histopathological cerebral glioma grading to determine whether it can be used as a non-invasive predictor of cerebral glioma grade.

MATERIALS AND METHODS

Fifty patients with suspected cerebral gliomas on imaging scheduled to undergo resection were included. We tested our hypothesis that with increasing glioma grade, increased tumor cellularity should translate into increased electron density and if a statistically significant difference between electron density of low-grade gliomas and high-grade gliomas is seen, we may have a clinical use of dual energy computed tomography as a non-invasive tool to predict cerebral glioma grade.A pre-operative dual energy computed tomography scan of the brain was performed, and electron density measurements calculated from the solid part of the tumor. Obtaining a ratio with electron density of contralateral normal brain parenchyma normalized these values. The minimum, maximum and mean electron density and their normalized values recorded between high-grade gliomas and low-grade gliomas were compared for presence of statistical significance.

RESULTS

A statistically significant difference was found between all six parameters recorded (minimum electron density and normalized values, mean electron density and normalized values, maximum electron density and normalized values) between low-grade gliomas and high-grade gliomas. The predictivity ranged from 75% (for minimum electron density and maximum normalized values) to 81.25% (for mean normalized values). All six parameters were found to have statistically significant positive correlation with Ki-67 index.

CONCLUSION

Dual energy computed tomography electron density measurements in cerebral gliomas are predictive of pre-operative differentiation of low-grade gliomas from high-grade gliomas and show a linear, statistically significant positive correlation with Ki-67 index.

CT-guided bone biopsy using electron density maps from dual-energy CT

Computed tomography (CT) -guided bone biopsy is a diagnostic procedure performed on the musculoskeletal system with a high diagnostic yield and low complications. However, CT-guided bone biopsy has the disadvantage that it is difficult to confirm the presence of tumor cells during the biopsy procedure. Recently, the clinical benefits of dual-energy CT (DECT) over single-energy CT have been revealed. DECT can provide material decomposition images including calcium suppression images, and effective atomic number (Z_eff) and electron density (ED) maps. ED maps have been reported to indicate cellularity. A 61-year-old woman with a history of breast cancer surgery was admitted to our hospital and underwent a CT-guided bone biopsy of the right ilium using ED maps. As a result, she was diagnosed with breast cancer metastases of intertrabecular bone. A comparison of ED maps with a pathological specimen revealed that high ED values occurred exclusively in the tumor area with high cellularity. This study indicates that ED maps produced using DECT may have potential utility in the accurate identification of metastases with high cellularity in bone lesions.

Dual-Energy CT-Derived Electron Density for Diagnosing Metastatic Mediastinal Lymph Nodes in Non-Small Cell Lung Cancer: Comparison With Conventional CT and FDG PET/CT Findings

Background: Accurate nodal staging is essential to guide treatment selection in patients with non-small cell lung cancer (NSCLC). To our knowledge, measurement of electron density (ED) using dual-energy CT (DECT) is unexplored for this purpose. Objective: To assess the utility of ED from DECT in diagnosing metastatic mediastinal lymph nodes in patients with NSCLC, in comparison with conventional CT and FDG PET/CT. Methods: This retrospective study included 57 patients (36 men, 21 women; mean age 68.4±8.9 years) with NSCLC and surgically resected mediastinal lymph nodes who underwent preoperative DECT and FDG PET/CT. The patients had a total of 117 resected mediastinal lymph nodes (33 metastatic, 84 nonmetastatic). Two radiologists independently reviewed nodes' morphologic features on the 120 kVp images and also measured nodes' iodine concentration (IC) and ED using maps generated from DECT data; consensus was reached for discrepancies. Two separate radiologists assessed FDG PET/CT examinations in consensus for positive node uptake. Diagnostic performance was evaluated for individual and pairwise combinations of features. Results: The sensitivity, specificity, and accuracy for nodal metastasis were 15.2%, 98.8%, and 75.2% for presence of necrosis; 54.5%, 85.7%, and 76.9% for short-axis diameter >8.5 mm; 63.6%, 73.8%, and 70.9% for long-axis diameter >13.0 mm; 51.5%, 79.8%, and 71.8% for attenuation on 120 kVp images ≤95.8 HU; 87.9%, 58.3%, and 66.7% for ED ≤3.48×1023/cm3; and 66.7%, 75.0%, and 72.6% for positive FDG uptake, respectively. Among pairwise combinations of features, accuracy was highest for the combination of ED and short-axis diameter (accuracy 82.9%, sensitivity 54.5%, specificity 94.0%) and the combination of ED and positive FDG uptake (accuracy 82.1%, sensitivity 60.6%, specificity 90.5%); these accuracies were greater than for the individual features (p<.05). Remaining combinations exhibited accuracies ranging from 74.4% to 77.8%. Interobserver agreement analysis demonstrated intraclass correlation coefficient of 0.90 for ED. IC was not significantly different between metastatic and nonmetastatic nodes (p=.18) and was excluded from the diagnostic performance analysis. Conclusion: ED derived from DECT may help diagnose metastatic lymph nodes in NSCLC given decreased ED in metastatic nodes. Clinical Impact: ED may complement conventional CT findings and FDG uptake on PET/CT in diagnosing metastatic nodes.

Dual-layer detector spectral CT-a new supplementary method for preoperative evaluation of glioma

PURPOSE

To investigate the value of the iodine concentration (IC) measured by dual-layer detector spectral CT (DLDSCT) in evaluating the factors related to the treatment scheme and survival prognosis of patients with glioma.

METHODS

From 2018 to 2019, we prospectively collected the data of 99 patients with glioma. The degree of CT enhancement and the IC of low grade gliomas (LGGs, II), high grade gliomas (HGGs, III and IV), grade II and III gliomas, were compared. The predictive performance of the degree of CT enhancement and IC was examined via receiver operating characteristic (ROC) analysis. The correlations between IC and Ki-67 labeling index, isocitrate dehydrogenase (IDH) mutation, chromosome 1p/19q deletion status of the tumor were examined.

RESULTS

Both IC and the degree of CT enhancement of patients with HGG were significantly higher than those of patients with LGG (p < 0.001; χ² =41.707, p <  0.001); IC had large area under the ROC curve for diagnostic HGG (0.931; 95 % CI: 0.882-0.979; p <  0.001). The IC in the grade III gliomas was significantly higher than that in grade II gliomas (p < 0.001); IC had a large area under the ROC curve for diagnostic grade III gliomas (0.865; 95 % CI: 0.779-0.952; p <  0.001). There was a significant positive correlation between IC and Ki-67 LI (r = 0.679; p < 0.001).

CONCLUSIONS

The DLDSCT technology can be used as a supplementary method to provide more information for preoperative grading of the gliomas and the prognosis assessment of the patients.

A Review of the Applications of Dual-Energy CT in Acute Neuroimaging

Dual-energy computed tomography (CT) is a promising tool with increasing availability and multiple emerging and established clinical applications in neuroradiology. With its ability to allow characterization of materials based on their differential attenuation when imaged at two different energy levels, dual-energy CT can help identify the composition of brain, neck, and spinal components. Virtual monoenergetic imaging allows a range of simulated single energy-level reconstructions to be created with postprocessing. Low-energy reconstructions can aid identification of edema, ischemia, and subtle lesions due to increased soft tissue contrast as well as increasing contrast-to-noise ratios on angiographic imaging. Higher energy reconstructions can reduce image artifact from dental amalgam, aneurysm clips and coils, spinal hardware, dense contrast, and dense bones. Differentiating iodine from hemorrhage may help guide management of patients after thrombectomy and aid diagnosis of enhancing tumors within parenchymal hemorrhages. Iodine quantification may predict hematoma expansion in aneurysmal bleeds and outcomes in traumatic brain injury. Calcium and bone subtraction can be used to distinguish hemorrhage from brain parenchymal mineralization as well as improving visualization of extra-axial lesions and vessels adjacent to dense plaque or skull. This article reviews the basics of dual-energy CT and highlights many of its clinical applications in the evaluation of acute neurological presentations.

Utility of dual-energy CT for predicting the vascularity of meningiomas

PURPOSE

Dual-energy computed tomography (DECT) can provide iodine, electron density (ED), and effective atomic number Z (Z_eff) maps, facilitating the identification of tissue types. We investigated whether DECT parameters can predict the vascularity of meningiomas.

METHOD

We acquired DECT and perfusion CT (PCT) images in 24 patients with histologically diagnosed meningioma. Regions of interest (ROIs) were placed at the tumor in iodine, ED, and Z_eff maps derived from DECT and in a blood volume (BV) map derived from PCT. To normalize these parameters' values, we divided them by the values of contralateral normal-appearing white matter, i.e., the relative (r)ED, rZ_eff, and rBV. The vascular density of the tumor specimens was immunohistochemically analyzed by calculating the von Willebrand factor-positive vessel wall. We calculated Pearson's correlation coefficients to determine the correlation with PCT/DECT parameters and an immunohistopathological index.

RESULTS

Contrast rZ_eff (r = 0.7020, p = 0.0001) and iodine (r = 0.5814, p = 0.0029) both had positive correlations with rBV derived from PCT. The rED values were negatively correlated with the rBV values (r = -0.4735, p = 0.0194), and the vascular density results confirmed positive correlations with rBV (r = 0.6909, p = 0.0002) and contrast rZ_eff (r = 0.4982, p = 0.0132) and a negative correlation with rED (r = -0.4265, p = 0.0377). Regarding the radiation exposure, the mean estimated volume CT dose index (CTDI_vol) of DECT was 33.1 ± 1.72 mGy, much lower than that of PCT (103.3 ± 4.65 mGy).

CONCLUSIONS

DECT predicted vascular density with lower radiation exposure compared to PCT. DECT could potentially replace PCT for evaluating the vascularity of meningiomas.