Erosive Progression by High-Resolution Peripheral Quantitative Computed Tomography and Conventional Radiography in Rheumatoid Arthritis.

OBJECTIVES: To investigate the diagnostic accuracy of high-resolution peripheral quantitative computed tomography (HR-pQCT) to assess erosive progression during one year compared to conventional radiography (CR) in rheumatoid arthritis (RA). METHODS: This prospective study included 359 patients with RA (disease duration ≥ 5 years) between March 2018 and October 2020. HR-pQCT and CR were obtained at inclusion and after one year. Erosive assessment was performed at two metacarpophalangeal joints of the dominant hand using HR-pQCT and progression was defined as an increase in erosion number ≥ 1 or an increase in erosive volume > least significant change. CR of hands, wrists, and feet were evaluated using Sharp/van der Heijde scores and erosive progression was defined as a 1.1-point increase in erosion score according to the smallest detectable change. RESULTS: In paired analyses (n = 310), erosive progression was identified in 30 patients using CR and in 40 patients using HR-pQCT. In the 40 patients with erosive progression on HR-pQCT, progression was not identified by CR in 33 patients. Adding HR-pQCT to CR doubled the proportion of patients identified with progression from 30 (10%) to 63 (20%) patients. Using CR as the reference, the sensitivity (% (95% CI)) of HR-pQCT for identifying erosive progression was 23.3 (9.9-42.3) and the specificity was 88.2 (83.8-91.7). CONCLUSION: A substantial proportion of patients with erosive progression are overlooked using CR only to monitor erosive progression. Adding high-resolution peripheral CT to CR doubles the proportion of patients, who may benefit from individualised therapy targeting erosive progression in RA.

Bone Mineral Density Derived from Cardiac CT Scans: Using Contrast Enhanced Scans for Opportunistic Screening.

PURPOSE: Osteoporosis is under-diagnosed and often co-exists with other diseases. Very low bone mineral density (BMD) indicates risk of osteoporosis and opportunistic screening for low BMD in CT-scans has been suggested. In a non-contrast enhanced thoracic CT scan, the scan-field-of-view includes vertebrae enabling BMD estimation. However, many CT scans are obtained by administration of contrast material. If the impact of contrast enhancement on BMD measurements could be quantified, considerably more patients are eligible for screening. METHODS: This study investigated the impact of intravenous contrast on thoracic BMD measurements in cardiac CT scans pre- and post-contrast, including different contrast trigger levels of 130 and 180 Hounsfield units (HU). BMD was measured using quantitative CT with asynchronous calibration. RESULTS: In 195 participants undergoing cardiac CT (mean age 57±9 years, 37 % females) contrast increased mean thoracic BMD from 116±33 mg/cm3 (non-enhanced CT) to 130±38 mg/cm3 (contrast-enhanced CT) (p<0.001). Using clinical cut-off values for very low (<80 mg/cm3) and low BMD (<120 mg/cm3) showed that 24 % (47/195 participants) were misclassified when BMD was measured on contrast-enhanced CT-scans. Of the misclassified patients, 6 % (12/195 participants) were categorized as having low BMD despite having very low BMD on the non-enhanced images. Contrast-CT using a higher contrast trigger level showed a significant increase in BMD compared to the lower trigger level (119±32 vs. 135±40 mg/cm3, p<0.01). CONCLUSION: For patients undergoing cardiac CT, using contrast-enhanced images to assess BMD entails substantial overestimation. Contrast protocol trigger levels also affect BMD measurements. Adjusting for these factors is needed before contrast-enhanced images can be used clinically. MINI ABSTRACT: Osteoporosis is under-diagnosed. Contrast-enhanced CT made to examine other diseases might be utilized simultaneously for bone mineral density (BMD) screening. These scans, however, likely entails overestimation of BMD due to the effect of contrast. Adjusting for this effect is needed before contrast-enhanced images can be implemented clinically for BMD screening.

The Minimal Erosive Volume Needed for Radiographic Identification of Erosions in the Metacarpophalangeal Joints in Patients With Rheumatoid Arthritis.

OBJECTIVE: To compare in images, obtained by high-resolution peripheral quantitative computed tomography (HR-pQCT) and conventional radiography (CR) of the second and third metacarpophalangeal (MCP) joints, the minimal erosive cortical break needed to differentiate between pathological and physiological cortical breaks. METHODS: In this single-center cross-sectional study, patients with established rheumatoid arthritis (disease duration ≥ 5 yrs) had their second and third MCP joints of the dominant hand investigated by HR-pQCT and CR. Empirical estimation was used to find the optimal cut-off value for the number of erosions and total erosive volume, which were detectable between patients with and without erosions in the second and third MCP joints according to CR. RESULTS: The total erosive volume in the second and third MCP joints by HR-pQCT for CR-detected erosive disease was estimated to be 56.4 mm3 (95% CI 3.5-109.3). The sensitivity and specificity at this cutpoint were 78% and 83%, respectively, with an area under the receiver-operating characteristic curve (AUC) of 0.81. The optimal cut-off value for the number of erosions by HR-pQCT was 8.5 (95% CI 5.9-11.1) for CR-detected erosive disease in the second and third MCP joints. The sensitivity and specificity at this cutpoint were 74% and 88%, respectively, with an AUC of 0.81. CONCLUSION: Erosions by HR-pQCT were larger in patients with erosive damage in the second and third MCP joints by CR. We found that CR had poor sensitivity for detecting erosive disease when the erosive volume was < 56.4 mm3 or the number of erosions was < 8.5.

Potential impact of texture analysis in contrast enhanced CT in non-small cell lung cancer as a marker of survival: A retrospective feasibility study.

The objective of this feasibility study was to assess computed tomography (CT) texture analysis (CTTA) of pulmonary lesions as a predictor of overall survival in patients with suspected lung cancer on contrast-enhanced computed tomography (CECT). In a retrospective pilot study, 94 patients (52 men and 42 women; mean age, 67.2 ±â€…10.8 yrs) from 1 center with non-small cell lung cancer (NSCLC) underwent CTTA on the primary lesion by 2 individual readers. Both simple and multivariate Cox regression analyses correlating textural parameters with overall survival were performed. Statistically significant parameters were selected, and optimal cutoff values were determined. Kaplan-Meier plots based on these results were produced. Simple Cox regression analysis showed that normalized uniformity had a hazard ratio (HR) of 16.059 (3.861-66.788, P < .001), and skewness had an HR of 1.914 (1.330-2.754, P < .001). The optimal cutoff values for both parameters were 0.8602 and 0.1554, respectively. Normalized uniformity, clinical stage, and skewness were found to be prognostic factors for overall survival in multivariate analysis. Tumor heterogeneity, assessed by normalized uniformity and skewness on CECT may be a prognostic factor for overall survival.

Assessment of Correlation between Dual-Energy Ct (De-Ct)-Derived Iodine Concentration and Local Flourodeoxyglucose (Fdg) Uptake in Patients with Primary Non-Small-Cell Lung Cancer.

(1) The current literature contains several studies investigating the correlation between dual-energy-derived iodine concentration (IC) and positron emission tomography (PET)-derived Flourodeoxyglucose (18F-FDG) uptake in patients with non-small-cell lung cancer (NSCLC). In previously published studies, either the entire tumor volume or a region of interest containing the maximum IC or 18F-FDG was assessed. However, the results have been inconsistent. The objective of this study was to correlate IC with FDG both within the entire volume and regional sub-volumes of primary tumors in patients with NSCLC. (2) In this retrospective study, a total of 22 patients with NSCLC who underwent both dual-energy CT (DE-CT) and 18F-FDG PET/CT were included. A region of interest (ROI) encircling the entire primary tumor was delineated, and a rigid registration of the DE-CT, iodine maps and FDG images was performed for the ROI. The correlation between tumor measurements and area-specific measurements of ICpeak and the peak standardized uptake value (SUVpeak) was found. Finally, a correlation between tumor volume and the distance between SUVpeak and ICpeak centroids was found. (3) For the entire tumor, moderate-to-strong correlations were found between SUVmax and ICmax (R = 0.62, p = 0.002), and metabolic tumor volume vs. total iodine content (R = 0.91, p < 0.001), respectively. For local tumor sub-volumes, a negative correlation was found between ICpeak and SUVpeak (R = −0.58, p = 0.0046). Furthermore, a strong correlation was found between the tumor volume and the distance in millimeters between SUVpeak and ICpeak centroids (R = 0.81, p < 0.0001). (4) In patients with NSCLC, high FDG uptakes and high DE-CT-derived iodine concentrations correlated on a whole-tumor level, but the peak areas were positioned at different locations within the tumor. 18F-FDG PET/CT and DE-CT provide complementary information and might represent different underlying patho-physiologies.

Diagnostic accuracy of high-resolution peripheral quantitative computed tomography and X-ray for classifying erosive rheumatoid arthritis.

OBJECTIVE: To investigate whether high-resolution peripheral quantitative CT (HR-pQCT) of two metacarpophalangeal (MCP) joints can more accurately classify patients as having erosive RA compared with conventional radiography (CR) of 44 joints in the hands, wrists and feet. METHODS: In this single-centre cross-sectional study, patients with established RA (disease duration ≥5 years) were investigated by HR-pQCT and CR. The second and third MCP joints of the dominant hand were assessed for erosions by HR-pQCT. CR of the hands, wrists and feet were scored according to the Sharp-van der Heijde (SHS) method. RESULTS: In total, 353 patients were included; 66 (18.7%) patients were classified as having non-erosive RA, and 287 (81.3%) had erosive RA by CR. The sensitivity and specificity (95% CI) of HR-pQCT for classifying patients as having erosive RA when standard CR of hands, wrists and feet was used as the reference was 89% (84, 92%) and 30% (20, 43%), respectively. Using HR-pQCT as the reference, the sensitivity and specificity of CR for classifying patients having erosive RA were 85% (80, 89%) and 38% (25, 52%), respectively. McNemar's χ2 test showed no significant difference between the sensitivities of patients classified as having erosive RA by HR-pQCT or by CR (2.14, P = 0.177). CONCLUSION: The diagnostic accuracy of HR-pQCT scanning of only two MCP joints and CR of 44 joints suggests the two modalities were comparable for classifying patients with established RA as having erosive disease. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT03429426).

Prognostic Utility of Parameters Derived From Pretreatment Dual-Layer Spectral-Detector CT in Patients With Metastatic Renal Cell Carcinoma.

BACKGROUND. New therapies have emerged for metastatic renal cell carcinoma (mRCC), though corresponding imaging markers are lacking. Dual-layer spectral-detector CT (DLCT) can quantify iodine concentration (IC) and effective atomic number (Zeffective), providing information beyond attenuation that may indicate mRCC prognosis. OBJECTIVE. The purpose of our study was to assess the utility of the DLCT-derived parameters IC and Zeffective for predicting mRCC treatment response and survival. METHODS. This prospective study enrolled 120 participants with mRCC from January 2018 to January 2020 who underwent DLCT, with reconstruction of IC and Zeffective maps, before treatment initiation. Final analysis included 115 participants (86 men, 29 women; median age, 65.1 years), incorporating 313 target lesions that were clinically selected using RECIST version 1.1 on arterial phase acquisitions of the chest and abdomen. Semiautomatic volumetric segmentation was performed of the target lesions. Voxels from all lesions were combined to a single histogram per patient. The median IC and Zeffective of the combined histograms were recorded. Measurements above and below the cohort median values were considered high and low, respectively. Univariable associations were explored between IC and Zeffective with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Multivariable associations were explored between IC and ORR, PFS, and OS, adjusting for treatment (tyrosine kinase inhibitor vs checkpoint immunotherapy) and significant univariable predictors (including tumor histology and International Metastatic Renal Cell Carcinoma Database Consortium [IMDC] risk factors). RESULTS. At baseline, median IC was 2.26 mg/mL, and median Zeffective was 8.49. In univariable analysis, high IC and high Zeffective were associated with better ORR (both, odds ratio [OR] = 4.35; p = .001), better PFS (both, hazard ratio [HR] = 0.51; p = .004), and better OS (both, HR = 0.38; p < .001). In multivariable models, high IC independently predicted better ORR (OR = 4.35, p = .001), better PFS (HR = 0.51, p = .004), and better OS (HR = 0.37, p < .001); neutrophilia independently predicted worse PFS (HR = 2.10, p = .004) and worse OS (HR = 2.28, p = .003). The estimated C-index for predicting OS using IMDC risk factors alone was 0.650 versus 0.687 when incorporating high attenuation and 0.692 when incorporating high IC or high Zeffective. CONCLUSION. High IC and high Zeffective are significant predictors of better treatment response and survival in mRCC. CLINICAL IMPACT. Baseline DLCT parameters may improve current mRCC prognostic models. TRIAL REGISTRATION. ClinicalTrials.gov NCT03616951.

Economic impact of spectral body imaging in diagnosis of patients suspected for occult cancer.

BACKGROUND: Based on prior studies spectral CT has shown a higher sensitivity for malignant lesions than conventional CT at the cost of lower specificity. For the radiologists, it also offers a higher degree of certainty in the diagnosis of benign lesions. The objective of this study was to evaluate the economic impact of spectral CT in patients suspected of occult cancer in a medical center in Denmark. METHODS: This study was a secondary analysis using de-identified data from a prospective study of patients receiving a contrast-enhanced spectral CT scan. Based on suggested follow-up examinations on both spectral CT and contrast-enhanced CT, costs from a payer's perspective were determined using unit costs obtained from national databases. RESULTS: The dataset contained 400 patients. Overall, 203 follow-up procedures were eliminated based on spectral data reading. The largest reduction in suggested follow-up procedures was found for the kidney (83%), followed by the liver (66%), adrenal glands (60%), and pancreas (42%). The total estimated costs for suggested follow-up procedures based on spectral data reading were €155,219, 25.2% (€52,384) less than that of conventional CT reading. CONCLUSION: Our results provide support for spectral body imaging as an advanced imaging modality for suspected occult cancer. A substantial number of follow-up diagnostic procedures could be eliminated based on spectral data reading, which would result in significant cost savings.

Sex Differences in the Association Between Bone Mineral Density and Coronary Artery Disease in Patients Referred for Cardiac Computed Tomography.

Atherosclerosis and osteoporosis are both common and preventable diseases. Evidence supports a link between coronary artery disease (CAD) and low bone mineral density (BMD). This study aimed to assess the association between thoracic spine BMD and CAD in men and women with symptoms suggestive of CAD. This cross-sectional study included 1487 (mean age 57 years (range 40-80), 47% men) patients referred for cardiac computed tomography (CT). Agatston coronary artery calcium score (CACS), CAD severity (no, mild, moderate, and severe), vessel involvement (no, 1-, 2-, and 3/left main disease), and invasive measurements were evaluated. BMD of three thoracic vertebrae was measured using quantitative CT. We used the American college of radiology cut-off values for lumbar spine BMD to categorize patients into very low (<80 mg/cm3), low (80-120 mg/cm3), or normal BMD (>120 mg/cm3). BMD as a continuous variable was included in the linear regression analyses to assess associations between CACS (CACS=0, CACS 1- 399, and CACS ≥ 400) and BMD, and CAD severity and BMD. Significant lower BMD was present with increasing CACS and stenosis degree unadjusted. Multivariate linear regression analyses in women revealed a significant correlation between BMD and CACS groups (ß = -4.06, p<0.05), but no correlation between BMD and CAD severity (ß = -1.59, p = 0.14). No association was found between BMD and CACS (ß = -1.50, p = 0.36) and CAD severity (ß = 0.07, p = 0.94) in men. BMD is significantly correlated to CACS after adjusting for confounders in women, but not in men, suggesting a possible sex difference in pathophysiology.

Effect of radiographic disease severity in high-resolution quantitative computed tomography assessment of metacarpophalangeal joint erosion and cysts.

AIM: Bone erosions are the hallmark of rheumatoid arthritis (RA). High-resolution peripheral quantitative computed tomography (HR-pQCT) enables 3-dimensional visualization of arthritic bone erosions at a high resolution. However, the degree of erosive disease could influence the reliability of HR-pQCT evaluation. We aim to assess the intra- and inter-reader variability of identification of erosions in the metacarpophalangeal (MCP) joints using HR-pQCT in healthy controls and patients with RA, stratified according to van der Heijde-modified Sharp Score (HSS) of radiographic erosions. METHOD: We analyzed HR-pQCT images from 78 patients with RA and 25 healthy controls. Patients were allocated to one of three groups of mild, moderate or severe disease according to HSS of MCP joints 2 and 3. Total HR-pQCT scans were analyzed twice in random order by three experienced readers, blinded to group distribution. The number of cortical interruptions and their classification as either erosions or cysts according to predefined criteria were recorded. Intraclass correlation coefficients (ICC) for cortical interruptions, erosions and cysts were calculated for each group using a 2-way random-effects model for inter-reader ICC and a 2-way mixed-effects model for intra-reader ICC. RESULTS: The intra- and inter-reader ICC were good to moderate for cortical interruptions and moderate for erosions throughout disease severity groups. The ICCs for the identification of cysts decreased with increasing degree of erosive disease. CONCLUSION: The detection of cortical interruptions is only minimally affected by the degree of erosive damage, whereas the distinction between erosions and cysts is more complex in patients with extensive erosive disease.

Thoracic Bone Mineral Density Derived from Cardiac CT Is Associated with Greater Fracture Rate.

Background Osteoporosis is a prevalent, under-diagnosed, and treatable disease associated with increased fracture risk. Bone mineral density (BMD) derived from cardiac CT may be used to determine fracture rate. Purpose To assess the association between fracture rate and thoracic BMD derived from cardiac CT. Materials and Methods This prospective cohort study included consecutive participants referred for cardiac CT for evaluation of ischemic heart disease between September 2014 and March 2016. End of follow-up was June 30, 2018. In all participants, volumetric BMD of three thoracic vertebrae was measured by using quantitative CT software. The primary and secondary outcomes were any incident fracture and any incident osteoporosis-related fracture registered in the National Patient Registry, respectively. Hazard ratios were assessed by using BMD categorized as very low (<80 mg/cm3), low (80-120 mg/cm3), or normal (>120 mg/cm3). The study is registered at ClinicalTrials.gov (identifier: NCT02264717). Results In total, 1487 participants (mean age, 57 years ± 9; age range, 40-80 years; 52.5% women) were included, of whom 179 (12.0%) had very low BMD. During follow-up (median follow-up, 3.1 years; interquartile range, 2.7-3.4 years; range, 0.2-3.8 years), 80 of 1487 (5.3%) participants were diagnosed with an incident fracture and in 31 of 80 participants, the fracture was osteoporosis related. In unadjusted Cox regressions analyses, very low BMD was association with a greater rate of any fracture (hazard ratio, 2.6; 95% confidence interval [CI]: 1.4, 4.7; P = .002) and any osteoporosis-related fracture (hazard ratio, 8.1; 95% CI: 2.4, 26.7; P = .001) compared with normal BMD. After adjusting for age and sex, very low BMD remained associated with any fracture (hazard ratio, 2.1; 95% CI: 1.1, 4.2) and any osteoporosis-related fracture (hazard ratio, 4.0; 95% CI: 1.1, 14.6). Conclusion Routine cardiac CT can be used to help measure thoracic bone mineral density (BMD) to identify individuals who have low BMD and a greater fracture rate. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Bredella in this issue.

Impact of spectral body imaging in patients suspected for occult cancer: a prospective study of 503 patients.

OBJECTIVES: To investigate the diagnostic impact and performance of spectral dual-layer detector CT in the detection and characterization of cancer compared to conventional CE-CT. METHODS: In a national workup program for occult cancer, 503 patients (286 females and 217 males) were prospectively enrolled for a contrast-enhanced spectral CT scan. The readings were performed with and without spectral data available. A minimum of 3 months between interpretations was implemented to minimize recall bias. The sequence of reads for the individual patient was randomized. Readers were blinded for patient identifiers and clinical outcome. Two radiologists with 9 and 33 years of experience performed the readings in consensus. If disagreement, a third radiologist with 11 years of experience determined the outcome of the reading RESULTS: Significantly more cancer findings were identified on the spectral reading. In 73 cases of proven cancer, we found a sensitivity of 89% vs 77% and a specificity of 77% vs 83% on spectral CT compared to conventional CT. A slight increase in reading time in spectral images of 82 s was found (382 vs 300, p < 0.001). For all cystic lesions, the perceived diagnostic certainty increased from 30% being completely certain to 96% most pronounced in the kidney, liver, thyroid, and ovaries. And adding the spectral information to the reading gave a decrease in follow-up examination for diagnostic certainty (0.25 vs 0.81 per reading, p < 0.001). CONCLUSION: The use of contrast-enhanced spectral CT increases the confidence of the radiologists in correct characterization of various lesions and minimizes the need for supplementary examinations. KEY POINTS: • Spectral CT is associated with a higher sensitivity, but a slightly lower specificity compared to conventional CT. • Spectral CT increases the confidence of the radiologists. • The need for supplementary examinations is decreased, with only a slight increase in reading times.

CT-guided cryoablation of renal cancer: radiation burden and the associated risk of secondary cancer from procedural- and follow-up imaging.

OBJECTIVES: To estimate radiation dose and the associated risk of secondary cancer risk related to percutaneous cryoablation (PCA) and follow-up imaging in a cohort of patients treated for small renal masses (SRMs). METHODS: A total of 149 patients underwent PCA for a SRM at our institution. Based on CT dose reports, we calculated the mean effective dose for a CT-guided PCA procedure and post-ablative follow-up CT. Applying follow-up recommendations by a multidisciplinary expert panel, we calculated the total radiation dose for the PCA procedure and the CT surveillance program corresponding to a minimal and preferable follow-up regime (5-year vs 10-year). Estimates of the lifetime attributable cancer risk for different age groups were calculated based on the cumulative effective dose based on the latest BEIR VII report. RESULTS: Total dose for the PCA treatment and follow-up CTs amounted to 174 and 294 mSv for a minimal and preferable protocol, respectively. Follow-up CTs accounted for the majority of the total effective dose for the minimal and preferable protocol (89% vs 94%). CT fluoroscopy contributed only to a limited amount of the total radiation dose for the minimal and preferable protocol (1.8% vs 1.1%). A 70-year-old male undergoing PCA treatment has a lifetime attributable cancer risk of 0.8% (1 in 131) when completing the preferable follow-up protocol. The same regimen in a 30-year-old female results in a lifetime attributable risk of cancer of 3.4% (1 in 29). CONCLUSION: Radiation dose and the associated risk of secondary cancer are high for patients with SRMs undergoing PCA and post-ablative follow-up imaging in particular in younger patients. Radiation exposure in the PCA procedure itself accounts for only a limited amount of the total radiation. Radiologists and clinicians must strive to implement radiation dose saving measures especially with respect to the follow-up regime.

Feasibility of Opportunistic Screening for Low Thoracic Bone Mineral Density in Patients Referred for Routine Cardiac CT.

Despite being a frequent and treatable disease, osteoporosis remains under-diagnosed worldwide. Our study aim was to characterize the bone mineral density (BMD) status in a group of patients with symptoms suggestive of coronary artery disease (CAD) with low/intermediate risk profile undergoing routine cardiac computed tomography (CT) to rule out CAD. This cross-sectional study used prospectively acquired data from a large consecutively included cohort. Participants were referred for cardiac CT based on symptoms of CAD. Quantitative CT (QCT) dedicated software was used to obtain BMD measurements in 3 vertebrae starting from the level of the left main coronary artery. We used the American College of Radiology cut-off values for lumbar spine QCT to categorize patients into very low (<80 mg/cm3), low (80-120 mg/cm3), or normal BMD (>120 mg/cm3). Analyses included 1487 patients. Mean age was 57 years (range 40-80), and 52% were women. The number of patients with very low BMD was 105 women (14%, 105/773) and 74 men (10%, 74/714). The majority of patients with very low BMD was not previously diagnosed with osteoporosis (87%) and received no anti-osteoporotic treatment (90%). Opportunistic screening in patients referred for cardiac CT revealed a substantial number of patients with very low BMD. The majority of these patients was not previously diagnosed with osteoporosis and received no anti-osteoporotic treatment. Identification of these patients could facilitate initiation of anti-osteoporotic treatment and reduce the occurrence of osteoporosis-related complications.

A novel alignment procedure to assess calcified coronary plaques in histopathology, post-mortem computed tomography angiography and optical coherence tomography.

PURPOSE: Improve mapping and registration of longitudinal view on histopathology vessels in a three-dimensional alignment procedure for postmortem quantitative coronary plaque analyses. This new procedure is applied and results shown using calcified coronary plaque analyses within post-mortem computed tomography angiography (PMCTA), optical coherence tomography (OCT) and the gold standard of histopathology. RESULTS: In total, 338 annotated histopathology images were included, 166 PMCTA transversal images and 285 OCT images were aligned in the comparison. The results from the comparison using the alignment procedure showed overall that the calcified plaques seem to be overestimated by PMCTA and underestimated by OCT. CONCLUSIONS: The 3D fusion approach, aligning the images of PMCTA, OCT and histopathology as gold standard allowed for a slice-based comparison of the different modalities. The results showed that PMCTA overestimates the calcified plaques while OCT underestimates these, compared to histopathology.

Vertebral Bone Mineral Density Measured by Quantitative Computed Tomography With and Without a Calibration Phantom: A Comparison Between 2 Different Software Solutions.

Quantitative computed tomography (CT) can be used to quantify bone mineral density (BMD) in the spine from clinical CT scans. We aimed to determine agreement and precision of BMD measurements by 2 different methods: phantom-less internal tissue calibration and asynchronous phantom-based calibration in a cohort of patients with chronic kidney disease (CKD). Patients with CKD were recruited for CT angiography of the chest, abdomen, and pelvis. BMD was analyzed by 2 different software solutions using different calibration techniques; phantom-based by QCT Pro (Mindways Inc.) and phantom-less by Extended Brilliance Workspace (Philips Healthcare). Intraoperator reanalysis was performed on 53 patients (36%) for both methods. An interoperator reanalysis on 30 patients (20%) using the phantom-based method and 29 patients (19%) using the phantom-less method was made. XY- and Bland-Altman plots were used to evaluate method agreement. Phantom-based measured BMD was systematically higher than phantom-less measured BMD. Despite a small absolute difference of 3.3 mg/cm3 (CI: -0.2-6.9 mg/cm3) and a relative difference of 5.1% (CI: 2.2%-8.1%), interindividual differences were large, as seen by a wide prediction interval (PI: -47-40 mg/cm3). The Bland-Altman plot showed no systematic bias, apart from 5 outliers. Intraoperator variability was high for the phantom-less method (5.8%) compared to the phantom-based (0.8%) and the interoperator variability was also high for the phantom-less method (5.8%) compared to the phantom-based (1.8%). Despite high correlation between methods, the between-method difference on an individual level showed great variability. Our results suggest agreement between these 2 methods is insufficient to allow them to be used interchangeably in patients with CKD.

Diet-Induced Abdominal Obesity, Metabolic Changes, and Atherosclerosis in Hypercholesterolemic Minipigs.

BACKGROUND: Obesity and metabolic syndrome (MetS) are major risk factors for atherosclerotic diseases; however, a causal link remains elusive. Animal models resembling human MetS and its complications, while important, are scarce. We aimed at developing a porcine model of human MetS. METHODS: Forty pigs with familial hypercholesterolemia were fed a high fat + fructose diet for 30 weeks. Metabolic assessments and subcutaneous fat biopsies were obtained at 18 and 30 weeks, and fat distribution was assessed by CT-scans. Postmortem, macrophage density, and phenotype in fat tissues were quantified along with atherosclerotic burden. RESULTS: During the experiment, we observed a >4-fold in body weight, a significant but small increase in fasting glucose (4.1 mmol/L), insulin (3.1 mU/L), triglycerides (0.5 mmol/L), and HDL cholesterol (2.6 mmol/L). Subcutaneous fat correlated with insulin resistance, but intra-abdominal fat correlated inversely with insulin resistance and LDL cholesterol. More inflammatory macrophages were found in visceral versus subcutaneous fat, and inflammation decreased in subcutaneous fat over time. CONCLUSIONS: MetS based on human criteria was not achieved. Surprisingly, visceral fat seemed part of a healthier metabolic and inflammatory profile. These results differ from human findings, and further research is needed to understand the relationship between obesity and MetS in porcine models.

Image quality in coronary computed tomography angiography: influence of adaptive statistical iterative reconstruction at various radiation dose levels.

Background Computed tomography (CT) technology is rapidly evolving and software solution developed to optimize image quality and/or lower radiation dose. Purpose To investigate the influence of adaptive statistical iterative reconstruction (ASIR) at different radiation doses in coronary CT angiography (CCTA) in detailed image quality. Material and Methods A total of 160 CCTA were reconstructed as follows: 55 scans with filtered back projection (FBP) (650 mA), 51 scans (455 mA) with 30% ASIR (ASIR30), and 54 scans (295 mA) with 60% ASIR (ASIR60). For each reconstruction, subjective image quality was assessed by five independent certified cardiologists using a visual grading analysis (VGA) with five predefined image quality criteria consisting of a 5-point scale. Objective measures were contrast, noise, and contrast-to-noise ratio (CNR). Results The CTDIvol resulted in 10.3 mGy, 7.4 mGy, and 4.6 mGy for FBP, ASIR30, and ASIR60, respectively. Homogeneity of the left ventricular lumen was the sole aspect in which reconstruction algorithms differed with a decreasing effect for ASIR60 compared to FBP (estimated odds ratio [OR] = 0.49 [95% confidence interval (CI) = 0.32-0.76; P = 0.001]). Decreased sharpness and spatial- and low-contrast resolutions were observed when using ASIR instead of FBP, but differences were not statistically significant. Concerning objective measurements, noise increased significantly for ASIR30 (OR = 1.08; 95% CI = 1.02-1.14; P = 0.006) and ASIR60 (OR = 1.06; 95% CI = 1.01-1.12; P = 0.034) compared to FBP. Conclusion ASIR significantly decreased the subjectively assessed homogeneity of the left ventricular lumen and increased the objectively measured noise compared to FBP. Considering these results, ASIR at a reduced radiation dose should be implemented with caution.

Comparison of single and dual energy CT for stopping power determination in proton therapy of head and neck cancer.

BACKGROUND AND PURPOSE: Patients with head and neck (HN) cancer may benefit from proton therapy due to the potential for sparing of normal tissue. For planning of proton therapy, dual-energy CT (DECT) has been shown to provide superior stopping power ratio (SPR) determination in phantom materials and organic tissue samples, compared to single-energy CT (SECT). However, the benefit of DECT in HN cancer patients has not yet been investigated. This study therefore compared DECT- and SECT-based SPR estimation for HN cancer patients. MATERIALS AND METHODS: Fourteen HN cancer patients were DECT scanned. Eight patients were scanned using a dual source DECT scanner and six were scanned with a conventional SECT scanner by acquiring two consecutive scans. SECT image sets were computed as a weighted summation of the low and high energy DECT image sets. DECT- and SECT-based SPR maps were derived. Water-equivalent path lengths (WEPLs) through the SPR maps were compared in the eight cases with dual source DECT scans. Mean SPR estimates over region-of-interests (ROIs) in the cranium, brain and eyes were analyzed for all patients. RESULTS: A median WEPL difference of 1.9 mm (1.5%) was found across the eight patients. Statistically significant SPR differences were seen for the ROIs in the brain and eyes, with the SPR estimates based on DECT overall lower than for SECT. CONCLUSIONS: Clinically relevant WEPL and SPR differences were found between DECT and SECT, which could imply that the accuracy of treatment planning for proton therapy would benefit from DECT-based SPR estimation.