Dual-Layer Spectral CT for Advanced Tissue Characterization: Differentiating Bladder Neoplasm from Intraluminal Thrombus—A Case Report

A Clinical-Radiomic Combined Model based on Dual-Layer Spectral CT for Predicting Pathological T4 in Gastric Cancer.

Quantitative calcium-based assessment of osteoporosis in dual-layer spectral CT

To evaluate the ability of spectral CT to non-invasively monitor liver temperature in vivo during thermal ablation. Under a protocol approved by the Institutional Animal Care and Use Committee, domestic swine (n = 3) underwent microwave ablation (MWA). Four thermocouples were percutaneously placed in the ablation region under ultrasound guidance. Single-probe MWA was performed for 5min at 65W. Sequential dual-layer spectral CT scans were collected at 1-min intervals during and after ablation (n = 16 scans/subject). Pre- and post-ablation contrast-enhanced CTs were acquired. Virtual monoenergetic images (70keV) were used to mask gas bubbles and metal artifacts and to identify and segment ROIs at the thermocouple tips. Electron density weighted (EDW), effective atomic number (Z-eff), and conventional CT results were associated with temperature using correlation analysis and polynomial curve fitting. Explanted ablation zones were sectioned perpendicular to the probe track, and gross pathology was analyzed. Twelve thermocouples were placed near the MWA probe shaft at a mean distance of 8.3mm (range 2.5-24.0mm). Maximum measurements for each thermocouple ranged from 46 to 99°C (overall range 29-99°C). Temperature measurements were compared to corresponding spectral CT imaging results (n = 192). At the thermocouple locations, the mean EDW was 103.9 ± 0.97 (range 98.5-105.8). A negative linear correlation was found between temperature and EDW (r = - 0.570, 95%CI [- 0.483 - 0.645], p < 0.001, root mean squared error = 8.05°C). This proof-of-concept study demonstrated the feasibility of monitoring temperature in vivo using spectral CT during thermal ablation. Intraprocedural temperature feedback may improve treatment margin identification and monitoring of nearby critical structures.

Objective To explore the quantitative characteristics of pancreatic ductal adenocarcinoma (PDAC) in single-source dual energy spectral CT imaging. Methods From January 2013 to December 2014, 113 patients underwent dual phase contrast-enhanced gemstone spectral imaging (GSI) on Discovery CT 750 HD. All diagnoses were pathologically confirmed by surgery or biopsy. The spectral HU curves of PDAC were observed, the monochromatic CT values, the effective atomic number (Zeff), the iodine concentration (IC), water concentration (WC), and the corresponding normalized values (normalized monochromatic CT values, normalized Zeff, normalized IC, normalized WC) of the lesion and the pancreatic parenchyma in late arterial phase (AP) and portal venous phase (PP) were recorded. The measurements were performed three times repeatedly. Paired t test (normal distribution) or Wilcoxon test (non-normal distribution) were used for analyzing the differences between the two phases and between PDAC and pancreatic parenchyma. Results The monochromatic CT values of PDAC in AP were lower than in PP at each energy level and the difference was more marked at lower energy. The normalized monochromatic CT values increased with the increase of energy level in both AP and PP and the difference was more distinct at lower energy. The Zeff, IC and normalized IC of PDAC all had significant differences (P<0.05), while the WC, normalized Zeff, and normalized WC had no difference between AP and PP. The Zeff and IC of pancreatic parenchyma had significant differences (P<0.05), while the WC had no difference between AP and PP. The differences of Zeff, IC, and WC between PDAC and pancreatic parenchyma were significant in both two phases (P<0.05). Conclusions Dual phase CT spectral imaging showed characteristic quantitative parameters of pancreatic ductal adenocarcinoma. The monochromatic CT values, Zeff, and iodine concentration of PDAC were lower than those of pancreatic parenchyma in both AP and PP. The monochromatic CT values, Zeff, and iodine concentration of PDAC in late arterial phase were lower than those in portal venous phase. The differences were all more distinct at lower energy. Key words: Pancreatic neoplasms; Tomography, X-ray computed; Comparative study

Evaluation of microcirculation in asymptomatic cerebral infarction with multi-parameter imaging of spectral CT

Objective To study the clinical,histopathological,immunohistochemical features and the diagnosis and treatment of paraganglioma of urinary bladder. Methods Two cases of paraganglioma of urinary bladder were treated. The first case was a male with painless haematuria. The abdominal ultrasonography and CT scan showed a 2.5 cm× 2.0 cm mass in the right anterior wall of the bladder, and urine vanillylmandelic acid elevated to 17. 9- 31. 3 μmol/24 h (normal range 10- 35 μmol/24 h). The second case was a female who presented with 8 years history of headache and palpitation after voiding. Abdominal ultrasonography and CT scan showed a 2. 6 cm× 1.5 cm mass in the left wall of the bladder, and her urine vanillylmandelic acid was 35.3-43.3 μmol/24 h. Results One patient underwent transurethral resection (TURBT) and the other underwent partial cystectomy.The two cases were diagnosed as bladder paraganglioma by pathological examination. Immunohistochemically, the tumor cells were positive for CgA, Syn, NSE and S-100. No evidence of recurrence was detected during follow-up at 3 months and 3 years. Conclusions Paraganglioma of urinary bladder should be considered as a low grade malignancy. Partial cystectomy should be recommended. The diagnosis depends on clinical symptoms, pathological and immunohistochemical results. Key words: Urinary bladder neoplasms; Paraganglioma; Pathology, clinical

Background Previously reported dual-energy CT methods for detecting noncalcified gallstones have reduced accuracy for gallstones smaller than 9 mm. Purpose To develop a dual-energy CT method for differentiating isoattenuating gallstones from bile and compare it with previously reported dual-energy CT methods by using a prospective ex vivo phantom reader study. Materials and Methods From May 2017 to May 2018, gallstones were collected from 105 patients (34 men; mean age, 51 years; age range, 18-84 years) undergoing cholecystectomy and placed inside 120-mL vials containing ox bile. The vials were placed inside a water-filled phantom and were scanned with dual-layer dual-energy CT. Thirty isoattenuating gallstones (4.3-24.7 mm in diameter) were evaluated. Conventional CT images, virtual noncontrast images, and monoenergetic images at 200 and 40 keV were created. Segmented images were created by using a two-dimensional histogram of Compton and photoelectric attenuation. Six readers evaluated the presence of isoattenuating gallstones in each image. Intra- and interreader agreement was measured by using percentage agreement, diagnostic performance was evaluated by using mean area under the receiver operating characteristic curve (AUC) estimates and pairwise comparisons, and the agreement of gallstone sizes measured at pathologic examination with those measured on segmented images was compared by using Bland-Altman analysis. Results For all gallstones, segmented images provided the highest mean intrareader (88.1%) and interreader (88.2% and 93.6%) agreements for all readers and reading sessions and the highest overall AUC (0.99; 95% confidence interval [CI]: 0.97, 1.00; adjusted P < .02 for all). For gallstones larger than 9 mm, no significant difference was found between the segmented and monoenergetic AUCs (all P > .94, adjusted P > .05 for all). For gallstones measuring 9 mm or smaller, the segmented images had the highest overall AUC (0.99; 95% CI: 0.97, 1.00; adjusted P < .01 for all). The mean difference in stone sizes was -0.6 mm, with limits of agreement from 2.6 to -3.8 mm. Conclusion Segmented images from Compton and photoelectric attenuation coefficients improve detection of isoattenuating gallstones compared with previously reported dual-energy CT methods. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Matos in this issue.

To assess (i) the optical properties and depth of penetration of varying wavelengths of light in ex-vivo human bladder tissue, using specimens of normal bladder wall, transitional cell carcinoma (TCC) and bladder tissue after exposure to ionizing radiation; and (ii) to estimate the depth of bladder wall containing cancer that could potentially be treated with intravesical photodynamic therapy (PDT), assuming satisfactory tissue levels of photosensitizer. Materials and methods The study included 11 cystectomy specimens containing invasive TCC (five from patients who had previously received external-beam bladder radiotherapy, but with recurrent TCC) and three 'normal' bladders removed from patients treated by exenteration surgery for extravesical pelvic cancer. Full-thickness bladder wall and tumour samples were taken from these specimens and using an 'intravesical' and a previously validated interstitial model, the optical penetration depths (i.e. the tissue depth at which the light fluence is 37% of incident) were calculated at wavelengths of 633, 673 and 693 nm. There were no significant differences in light penetration between normal and tumour-affected bladder tissue at each wavelength. There were significant differences in light penetration among wavelengths; light at 693 nm penetrated approximately 40% further than light at 633 nm (P < 0.002). The light currently used in bladder PDT (633 nm) has a mean (SEM) optical penetration depth of 4.0 (0.1) mm within TCC. In addition, at this wavelength, there was 29% greater light penetration in previously irradiated than in unirradiated bladder wall (P = 0.001). This did not occur in the tumour-affected bladder. Bladder tissue is relatively more translucent than other human tissues and there is therefore great potential for PDT in the treatment of bladder cancer. As there is no difference in light penetration between TCC and normal bladder tissue, a tumour-specific response with diffuse illumination of the bladder will depend on drug localization within the tumour. The currently used wavelength of 633 nm can be expected to exert a PDT effect within bladder tumour up to a depth of 20 mm. Increasing the wavelength will allow deeper pathology to be treated.

Lung adenocarcinoma (LUAD) is the leading cause of cancer-related deaths. High-resolution computed tomography (HRCT) has improved the detection of ground glass nodules (GGNs), which are early indicators of lung cancer. Accurate assessment of GGN invasiveness is crucial for determining the appropriate surgical approach. Dual-layer spectral detector computed tomography (DLCT) offers advanced imaging capabilities, including electron density and iodine density, which enhance the evaluation of GGN invasiveness. This study aims to develop a machine learning (ML) model that integrates DLCT parameters and clinical features to predict the invasiveness of GGNs in LUAD, aiding in surgical decision-making and prognosis improvement. The retrospective study encompassed 272 patients who were diagnosed with LUAD, comprising154 cases of invasive adenocarcinomas(IA) and118 cases of pre-invasive minimally invasive adenocarcinoma (MIA) which were then randomly allocated into atraining setand atest set. Six ML models were developed based on five DLCT parameters (conventional, iodine density, virtual noncontrast, electron density, and effective atomic number). Subsequently, a nomogram was constructed using multi-factor logistic regression, incorporating radiomic characteristics and clinicopathological risk factors. The ML model based on conventional plus electron density performed better than the models with other DLCT parameters,with the area under the curves (AUCs) of0.945 and 0.964 in the training and test sets, respectively. The clinical model and radiomics score (Rad-score) were combinedin the logistic regression to construct a joint model,of which the AUCs were0.974 in the training sets and 0.949 in the test sets. The ML model effectively differentiated between IA and pre-invasive MIA, and further classified patients into high and medium risk categories for invasion using waterfall plots. The ML model based on DLCT parameters helpspredict the invasiveness of GGNs and classifiesthe GGNs intodifferent risk grades.

We explored the potential clinical value of material separation enabled by dual-energy spectral computed tomography in detecting left atrial appendage thrombi. The study enrolled 24 patients who were scheduled to undergo atrial fibrillation ablation (12 with and 12 without left atrial appendage thrombi). Computed tomograms were acquired in gemstone spectral imaging mode; the densities in the regions of the left atrial appendage cavities, pectinate muscles, and left atrial appendage thrombi were analyzed on monochromatic 70-keV images. Iodine and blood were chosen as the material basis pair; the iodine and blood densities were observed and quantitatively determined from the iodine- and blood-specific material decomposition images. On the 70-keV monochromatic and iodine-specific images, the left atrial appendage pectinate muscles and thrombi appeared as areas of hypodense attenuation. On the blood-specific images, similar areas of high attenuation were observed in the thrombi and cavities, whereas lower attenuation was noticed in the pectinate muscles. The quantitative iodine and blood densities in the pectinate muscles were lower than those in the cavities (P <0.001). The iodine densities in the thrombi were lower than those in the cavities (P <0.001); however, blood densities did not differ significantly between the thrombi and cavities (P=0.192). Compared with the pectinate muscles, the thrombi showed lower blood-density differences (P=0.003) and higher iodine-density differences (P=0.006) in relation to the cavities. Spectral computed tomography-enabled material separation is a novel method for differentiating left atrial appendage thrombi from pectinate muscles. The potential applications of this technology warrant further studies.

Definitive Chemoradiation in Bladder Cancer: Whole Bladder Versus Partial Bladder Image Guided IMRT

The aim was to evaluate Virtual Non-Contrast (VNC)-CT images for the detection of acute infarcts in the brain after mechanical thrombectomy using a dual-layer spectral CT. 29 patients between September 2016 and February 2017 with unenhanced head spectral-CT after mechanical thrombectomy and available follow-up images (MRI, n:26; CT, n:3) were included. VNC-CT and conventional CT (CT) images were reconstructed using dedicated software. Based on those, contrast-to-noise ratio (CNR), and the volume of infarction were measured semi-automatically in VNC-CT, CT and MRI. Furthermore, two readers independently assessed the VNC-CT and CT images in a randomized order by using the ASPECT score, and inter-rater reliability, sensitivity and specificity were calculated. CNR was significantly higher in VNC-CT compared to CT (3.1 ± 1.5 versus 1.1 ± 1.1, p < 0.001). The mean estimated volume of infarction was significantly higher in VNC-CT compared to CT (72% versus 55% of the volume measured in MRI, p < 0.005). Inter-rater reliability was higher in VNC-CT compared to CT (0.751 versus 0.625) and sensitivity was higher in VNC-CT compared to CT (73% versus 55%). In conclusion, acute ischemic lesions after mechanical thrombectomy are better definable in VNC-CT compared to CT images using a dual-layer spectral CT system.

To compare conventional and dual-energy CT (DECT) for the diagnosis of acute cholecystitis and gangrene. Fifty-seven consecutive adult patients with abdominal pain who underwent IV contrast-enhanced abdominal DECT on a dual-layer (dlDECT) or rapid-switching (rsDECT) scanner from September, 2018 to April, 2021 with cholecystectomy and pathology-confirmed cholecystitis were retrospectively reviewed, and compared with 57 consecutive adult patients without cholecystitis from the same interval scanned with DECT. Images were reviewed independently by two abdominal radiologists with 12 and 16years of experience in two sessions 4weeks apart, blinded to clinical data. Initially, only blended reconstructions (simulating conventional single-energy CT images) were reviewed (CT). Subsequently, CT and DECT reconstructions including low-keV virtual monoenergetic images and iodine maps were reviewed. Gallbladder fossa hyperemia, pericholecystic fluid, subjective presence of gangrene, heterogeneous wall enhancement, sloughed membranes, intramural air, abscess, overall impression of the presence of acute cholecystitis, and intramural iodine density were assessed. Gallbladder fossa hyperemia was detected with increased sensitivity on DECT (R1, 61.4%; R2, 75.4%) vs. CT (R1, 22.8%; R2, 15.8%). DECT showed increased sensitivity for gangrene (R1, 24.6%; R2, 38.6%) vs. CT (R1, 5.3%; R2, 14%), heterogeneous wall enhancement (DECT: R1, 33.3%; R2, 63.2% vs. CT: R1, 7%; R2, 31.6%), and cholecystitis (DECT: R1, 86%; R2, 89.5% vs. CT: R1, 77.2%; R2, 70.2%). In addition, DECT was more sensitive for the detection of acute cholecystitis (R1, 86%; R2, 89.5%) vs. CT (R1, 77.2%; R2, 70.2%). Iodine density threshold of 1.2mg/ml, 0.8mg/mL, and 0.5mg/mL showed specificity for gangrenous cholecystitis of 78.26%, 86.96%, and 95.65%, respectively, using the rsDECT platform. DECT showed improved sensitivity compared to conventional CT for detection of acute cholecystitis. Iodine density measurements may be helpful to diagnose gangrene.

A 77-year-old patient with history of non muscle invasive and recurrent multifocal bladder tumour (pTaG2), with superficial 4-mm recurrence in the fundus bladder mucosa during the follow-up, underwent a transurethral resection of bladder tumor (TURB). Without bladder perforation suspected, intravesical instillation Mitomycin-C in the immediate postoperative period was administered. In cystoscopy, 3 months later, with the patient being asymptomatic, a fibrino-stone like growing was observed, arising from fundus bladder mucosa (1, 2). In an attempt to dismiss a post TURB leak, a biopsy of the fibrinous material was taken and URO-CT performed, which revealed irregularity and a scar tract with some calcifications within the bladder anterior wall (Fig.1 and Fig.2). The histological result of the sample taken was adipose tissue, necrosis, lymphoplasmacytic inflammatory infiltrate and dystrophic calcifications (3), compatible with encrusted cystitis. With those findings in the anatomopathological report, urine sample was analyzed. The pH of the urine was 6 and the culture was negative, so encrustated cystitis was dismissed (4). Most probable, the changes in the bladder mucosa were due to a reactive process to the intravesical instillation of Mytomicin-C in a non-suspected microscopic perforation of bladder wall. During the follow-up after biopsy, the patient was asymptomatic and without pathological findings in the cystoscopy.

Dual-energy computed tomography for non-invasive staging of liver fibrosis: Accuracy of iodine density measurements from contrast-enhanced data.