Contrast Material-enhanced Computed Tomography Research Articles

Unresectable pancreatic ductal adenocarcinoma: Role of CT quantitative imaging biomarkers for predicting outcomes of patients treated with chemotherapy

ObjectivesThe primary aim of this study was to determine if computed tomographic (CT) texture analysis measurements of the tumor are independently associated with progression-free survival (PFS) and overall survival (OS) in patients with unresectable pancreatic ductal adenocarcinoma (PDAC), including both unresectable locally advanced and metastatic PDAC, who were treated with chemotherapy. MethodsAfter an institutional review board waiver was obtained, contrast material-enhanced CT studies in 41 patients with unresectable PDAC who underwent contrast-enhanced CT before chemotherapy between 2014 and 2017 were analyzed in terms of tumor texture, with quantification of mean gray-level intensity (Mean), entropy, mean of positive pixels (MPP), kurtosis, standard deviation (SD), and skewness for fine to coarse textures (spatial scaling factor (SSF) 0–6, respectively). The association between pretreatment and posttreatment texture parameters, as well as Δ value (difference between posttreatment and pretreatment texture parameters), and survival time was assessed by using Cox proportional hazards models and Kaplan-Meier analysis. ResultsFindings from the multivariate Cox model indicated that tumor size, tumor SD (HR, 0.942; 95% CI: 0.898, 0.988) and skewness (HR, 0.407; 95% CI: 0.172, 0.962) measurements with SSF = 3, and tumor SD (HR, 0.958; 95% CI: 0.92, 0.997) measurements with SSF = 4 were significantly and independently associated with PFS, while tumor size and tumor SD (HR, 0.928; 95% CI: 0.882, 0.976) measurements with SSF = 3 were significantly and independently associated with OS. None of the post-therapy texture parameters or Δ value had a significant association with OS or PFS in multivariate Cox regression models. Medium SD (SSF = 3) of more than 38.38 and coarse SD (SSF = 4) of more than 40.67 were associated with longer PFS after chemotherapy (for SSF = 3, median PFS was 10.0 vs 6.0 months [P = 0.024], and for SSF = 4, median PFS was 12.0 vs 6.0 months [P = 0.003]). SD of 38.38 or greater (SSF = 3) as a dichotomized variable was a significant positive prognostic factor for OS (median OS, 20.0 vs 9.0 months [P = 0.04]). Survival models that included a combination of pretreatment SD (SSF = 3) with tumor size, had the potential to perform better than SD alone, while having no statistical significance in this study (area under the ROC curve, 0.756 vs 0.715 [P = 0.066]). ConclusionsPretreatment CT quantitative imaging biomarkers from texture analysis are associated with PFS and OS in patients with unresectable PDAC who were treated with chemotherapy, and the combination of pretreatment texture parameters and tumor size have the potential to perform better in survival models than imaging biomarker alone.

Assessment of Bowel Wall Enhancement for the Diagnosis of Intestinal Ischemia in Patients with Small Bowel Obstruction: Value of Adding Unenhanced CT to Contrast-enhanced CT.

Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia, a complication of mechanical SBO, on the basis of decreased bowel wall enhancement. (©) RSNA, 2016.

Contrast-enhanced Reformatted MR Images for Preoperative Assessment of the Bridging Veins of the Skull Base.

Magnetic resonance (MR) venography and computed tomographic (CT) venography are suited for displaying the convexity veins that drain the medial and lateral surfaces of the brain hemispheres. However, such is not the case for the bridging veins of the skull base. Technical factors prevent contrast material-enhanced MR or CT images obtained in standard axial, coronal, and sagittal planes from fully displaying the curved pathways of these clinically important venous structures. This limitation can be overcome by using a reconstruction technique that depicts these venous structures and their interconnections. Curved and multiplanar reformatted images that distill the important venous features often require knowledgeable manipulation of source images by an operator who is familiar with numerous venous variants and their surgical implications. The normal anatomy of the draining veins is detailed-anatomy that radiologists must master before they can show the surgeon the important venous anatomy that is often missing at standard imaging; this information will foster better communication between radiologists and their surgical colleagues. As a practical matter, the skull base veins are arbitrarily subdivided into those that are at greatest risk with the pterional approach and the subtemporal approach, respectively. These approaches can be expanded to define connections between the superficial venous system and the other valveless venous networks that drain the deep portions of the cerebral hemisphere, the scalp, face, muscles of the neck, diploë of the skull, and meninges. As radiologists gain experience, their image interpretations should mature beyond simple analysis of the primary hemodynamic changes induced by intraoperative sacrifice or injury.

A Simplified Whole-Organ CT Perfusion Technique with Biphasic Acquisition: Preliminary Investigation of Accuracy and Protocol Feasibility in Kidneys.

To determine the feasibility and accuracy of a protocol for calculating whole-organ renal perfusion (renal blood flow [RBF]) and regional perfusion on the basis of biphasic computed tomography (CT), with concurrent dynamic contrast material-enhanced (DCE) CT perfusion serving as the reference standard. This prospective study was approved by the institutional review board, and written informed consent was obtained from all patients. Biphasic CT of the kidneys, including precontrast and arterial phase imaging, was integrated with a first-pass dynamic volume CT protocol and performed and analyzed in 23 patients suspected of having renal artery stenosis. The perfusion value derived from biphasic CT was calculated as CT number enhancement divided by the area under the arterial input function and compared with the DCE CT perfusion data by using the paired t test, correlation analysis, and Bland-Altman plots. Correlation analysis was made between the RBF and the extent of renal artery stenosis. All postprocessing was independently performed by two observers and then averaged as the final result. Mean ± standard deviation biphasic and DCE CT perfusion data for RBF were 425.62 mL/min ± 124.74 and 419.81 mL/min ± 121.13, respectively (P = .53), and for regional perfusion they were 271.15 mL/min per 100 mL ± 82.21 and 266.33 mL/min per 100 mL ± 74.40, respectively (P = .31). Good correlation and agreement were shown between biphasic and DCE CT perfusion for RBF (r = 0.93; ±10% variation from mean perfusion data [P < .001]) and for regional perfusion (r = 0.90; ±13% variation from mean perfusion data [P < .001]). The extent of renal artery stenosis was negatively correlated with RBF with biphasic CT perfusion (r = -0.81, P = .012). Biphasic CT perfusion is clinically feasible and provides perfusion data comparable to DCE CT perfusion data at both global and regional levels in the kidney. Online supplemental material is available for this article.

The Radiogenomic Risk Score: Construction of a Prognostic Quantitative, Noninvasive Image-based Molecular Assay for Renal Cell Carcinoma.

To evaluate the feasibility of constructing radiogenomic-based surrogates of molecular assays (SOMAs) in patients with clear-cell renal cell carcinoma (CCRCC) by using data extracted from a single computed tomographic (CT) image. In this institutional review board approved study, gene expression profile data and contrast material-enhanced CT images from 70 patients with CCRCC in a training set were independently assessed by two radiologists for a set of predefined imaging features. A SOMA for a previously validated CCRCC-specific supervised principal component (SPC) risk score prognostic gene signature was constructed and termed the radiogenomic risk score (RRS). It uses the microarray data and a 28-trait image array to evaluate each CT image with multiple regression of gene expression analysis. The predictive power of the RRS SOMA was then prospectively validated in an independent dataset to confirm its relationship to the SPC gene signature (n = 70) and determination of patient outcome (n = 77). Data were analyzed by using multivariate linear regression-based methods and Cox regression modeling, and significance was assessed with receiver operator characteristic curves and Kaplan-Meier survival analysis. Our SOMA faithfully represents the tissue-based molecular assay it models. The RRS scaled with the SPC gene signature (R = 0.57, P < .001, classification accuracy 70.1%, P < .001) and predicted disease-specific survival (log rank P < .001). Independent validation confirmed the relationship between the RRS and the SPC gene signature (R = 0.45, P < .001, classification accuracy 68.6%, P < .001) and disease-specific survival (log-rank P < .001) and that it was independent of stage, grade, and performance status (multivariate Cox model P < .05, log-rank P < .001). A SOMA for the CCRCC-specific SPC prognostic gene signature that is predictive of disease-specific survival and independent of stage was constructed and validated, confirming that SOMA construction is feasible.

Role of US Contrast Agents in the Assessment of Indeterminate Solid and Cystic Lesions in Native and Transplant Kidneys.

Ultrasonography (US) is often the initial imaging modality employed in the evaluation of renal diseases. Despite improvements in B-mode and Doppler imaging, US still faces limitations in the assessment of focal renal masses and complex cysts as well as the microcirculation. The applications of contrast-enhanced US (CEUS) in the kidneys have dramatically increased to overcome these shortcomings with guidelines underlining their importance. This article describes microbubble contrast agents and their role in renal imaging. Microbubble contrast agents consist of a low solubility complex gas surrounded by a phospholipid shell. Microbubbles are extremely safe and well-tolerated pure intravascular agents that can be used in renal failure and obstruction, where computed tomographic (CT) and magnetic resonance (MR) imaging contrast agents may have deleterious effects. Their intravascular distribution allows for quantitative perfusion analysis of the microcirculation, diagnosis of vascular problems, and qualitative assessment of tumor vascularity and enhancement patterns. Low acoustic power real-time prolonged imaging can be performed without exposure to ionizing radiation and at lower cost than CT or MR imaging. CEUS can accurately distinguish pseudotumors from true tumors. CEUS has been shown to be more accurate than unenhanced US and rivals contrast material-enhanced CT in the diagnosis of malignancy in complex cystic renal lesions and can upstage the Bosniak category. CEUS can demonstrate specific enhancement patterns allowing the differentiation of benign and malignant solid tumors as well as focal inflammatory lesions. In conclusion, CEUS is useful in the characterization of indeterminate renal masses and cysts.

Determining the normal aorta size in children.

To establish effective aorta diameter standards at multiple levels of the thoracic aorta, abdominal aorta, and common iliac arteries by using computed tomographic (CT) data in healthy children (infants, children, adolescents) through young adults (hereafter referred to collectively as "children") of a wide range of sizes so that z scores may be calculated. This retrospective study was approved by the institutional review board. The effective diameter, the average of aortic anteroposterior and lateral diameters, was independently measured at multiple levels of the aorta and common iliac arteries by two radiologists using 1-mm-collimation double-oblique reconstructions. Ordinary least squares regression methods were used to investigate models with various functional forms that related effective diameters at each level to patient body surface area (BSA) and sex. The best model was selected by using R(2), and formulas for deriving the expected diameter and estimates of the mean squared error (MSE) were generated. Results from 88 thoracic and 110 abdominal contrast material-enhanced CT examinations were analyzed in children without known cardiovascular disease who ranged in age from 0 to 20 years (mean, 9.9 years; standard deviation, 5.7), with BSA ranging from 0.19 to 2.52 m(2). Excellent interrater reliability was present (correlation coefficients ranged from 0.95 to 0.98). The best model was a polynomial regression model of the natural log transformation of the effective diameter that included linear, quadratic, and cubic BSA terms and a sex main effect as independent variables. The z scores were calculated by using the observed and expected effective diameters and the MSE. The range of normal effective diameters of the aorta at multiple levels and the common iliac arteries was determined for children of different sizes and both sexes. Measurements outside of the normal ranges are consistent with aneurysm or hypoplasia.

Model-based Iterative Reconstruction for Multi–Detector Row CT Assessment of the Adamkiewicz Artery

To determine if model-based iterative reconstruction (MBIR) can improve visualization of the Adamkiewicz artery on multi-detector row computed tomographic (CT) images compared with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP). This retrospective study was approved by the institutional review board, and written informed consent for the CT examination was obtained. Thirty-three patients underwent contrast material-enhanced 64-section multi-detector row CT for assessment of aortic aneurysm or dissection. Helical data were reconstructed by using FBP, ASIR, and MBIR. The signal-to-noise ratio of the aorta and contrast-to-noise ratio of the anterior spinal artery relative to the spinal cord were measured on multiplanar reformatted images. Visualization of the Adamkiewicz artery and its continuity with the intercostal or lumbar artery were evaluated by using a four-point scale. All image analyses were performed by two blinded, independent observers. The one-way analysis of variance and the Wilcoxon signed-rank test were used for statistical analysis. MBIR showed significantly better signal-to-noise and contrast-to-noise ratios than did ASIR and FBP (P < .05 for all comparisons) with good interobserver agreement (intraclass correlation coefficient of 0.93 for signal-to-noise ratio and 0.75 for contrast-to-noise ratio). The visualization score of the Adamkiewicz artery was also significantly better when MBIR was used (3.4 ± 0.8 and 3.6 ± 0.7 for observers A and B, respectively) than when ASIR (2.7 ± 1.1 and 3.0 ± 1.0, respectively) or FBP (2.5 ± 1.2 and 3.1 ± 0.9, respectively) was used. Use of the MBIR algorithm led to improved multi-detector row CT visualization of the Adamkiewicz artery when compared with the use of ASIR and FBP.

Innovative CT acquisition technique for the detection of hepatic nodules: What is the dose delivered to the patient?

Introduction A Fast-kVp Switching (FKS) dual-energy and a routine adaptative iterative reconstruction (Adaptative Statistical Iterative Reconstruction, ASIR, GE Healthcare®) single-energy abdominal Computed Tomography (CT) protocols have been designed for hepatocellular carcinomas detection. Previous studies have shown that FKS exams can deliver a higher dose than standard exam with comparable image quality. This study aims to evaluate the dose delivered to patient exposed to these CT protocols. Material and methods Ten patients with 31 hepatocellular carcinomas underwent FKS dual-energy (80–140 kV; 630 mA, rotation time: 0.5 s pitch: 1.375) and single-energy abdominal contrast materialenhanced (120 kV, 150–650 mA, rotation time: 0.7 s pitch: 1.375, ASIR 50%, FBP 50%) CT exams with liver-arterial and portal venous phases. For each exam, image quality was judged qualitatively and quantitatively on arterial phase by radiologists. Radiation dose, based on Volume CT Index (CTDIVOL) and Dose Length Product (DLP) was reported using a Dose Archiving and Communication System (DACS) (DoseWatch, GE HealthCare®). Since only single energy abdominal protocol uses Automatic Exposure Control (AEC), all the results were classified according to patients Body Mass Index (BMI). Results Image quality, allowed the identification of 94% (29/31) of HCC nodules with adaptative iterative reconstruction single-energy exam and 97% (30/31) with FKS dual-energy protocol. A CTDIVOL of 13 mGy and a mean DLP of 393 mGy.cm were determined for the dual energy protocol whathever BMI. Whereas, for the routine exam, mean CTDIVOL and DLP were 7 mGy, 215 mGy cm; 14 mGy, 454 mGy cm and 18 mGy, 783 mGy cm for BMIs less than 20, of 20–25 and greater than 25 BMI, respectively. Conclusion FKS dual-energy and adaptative iterative reconstruction single-energy abdominal CT protocols can be optimized so as to deliver a radiation dose lower than swiss dose reference level (15 mGy, 500 mGy cm) without neglecting image quality. Current FKS dual energy protocol could be optimized since it now uses adaptive iterative reconstruction. Moreover, it could be adapted to low BMI patients.

Tumor Volume of Resectable Adenocarcinoma of the Esophagogastric Junction at Multidetector CT: Association with Regional Lymph Node Metastasis and N Stage

To determine whether the volume of resectable adenocarcinoma of the esophagogastric junction (AEG) measured at multidetector computed tomography (CT) is associated with regional lymph node metastasis and N stage. The study was approved by the institutional ethics committee, and written informed consent was obtained from each participant. Two hundred sixteen patients with resectable AEG prospectively underwent contrast material-enhanced thoracoabdominal multidetector CT less than 2 weeks before curative resection. Gross tumor volume was retrospectively measured on CT scans. Univariate and multivariate analyses were performed to identify whether gross tumor volume is associated with regional lymph node metastasis. The Mann-Whitney U test was performed to compare gross tumor volume among N stages, with Bonferroni correction for multigroup comparisons. Receiver operating characteristic analysis was performed to determine if gross tumor volume could help classify N stage. Univariate analysis showed that gross tumor volume is associated with regional lymph node metastasis (P < .0001). Multivariate analysis revealed that gross tumor volume is an independent risk factor of lymph node metastasis (P = .023, odds ratio = 2.791). The Mann-Whitney U test showed that gross tumor volume could help differentiate between stage N0 and stages N1-N2 or N1-N3 disease and between stages N1-N2 and stage N3 disease (P < .0001 for all). In patients with stage T1-T3 AEG, gross tumor volume could help differentiate between stage N0 and stages N1-N2 (cutoff, 15.23 cm(3)) or N1-N3 (cutoff, 17.16 cm(3)) disease and between stages N1-N2 and stage N3 disease (cutoff, 33.96 cm(3)). In patients with stage T3 AEG, gross tumor volume could help differentiate stage N0 from stages N1-N2 (cutoff, 18.41 cm(3)) or N1-N3 (cutoff, 19.30 cm(3)) disease and stages N1-N2 from stage N3 disease (cutoff, 33.96 cm(3)). Gross tumor volume of AEG measured with multidetector CT is associated with regional lymph node metastasis and N stage.

Splenic lymphangioma that manifested as a solid-cystic mass: A case report

Lymphangioma, a congenital malformation of the lymphatic system, is usually found in children, and generally occurs in the neck and mediastinum. It is rarely found in the spleen. The clinical features of splenic lymphangioma typically include abdominal pain, nausea, and abdominal distention. Frequently, however, this condition is asymptomatic and is incidentally detected by abdominal ultrasonography or by an abdominal computed tomography (CT) scan. In this paper, we retrospectively describe a case of incidentally detected splenic lymphangioma in a 30-year-old woman with special abdominal contrast material-enhanced CT findings, which was accurately diagnosed by histopathology. The clinical and physical examinations related to the mass were negative. A few cases of splenic lymphangioma have been reported previously; however, the presentation of the mass and the enhancement pattern in the contrast medium-enhanced CT images were quite extraordinary. These findings had misled our abdominal radiologists to consider it as other neoplastic diseases of the spleen.

Effectiveness and Safety of CT-Guided &lt;sup&gt;125&lt;/sup&gt;I Brachytherapy for Lung Metastasis from Hepatocellular Carcinoma

To retrospectively evaluate effectiveness and safety of CT-guided 125I brachytherapy in patients with lung metastasis from hepatocellular carcinoma, sixty lung metastatic lesions in 29 patients were percutaneously treated in 34 125I brachytherapy sessions. Each metastatic lesion was treated with computed tomographic (CT) guidance. Follow-up contrast material-enhanced CT scans were reviewed and the efficacy of treatment was evaluated. Months are counted from the first time of 125I brachytherapy and the median duration of follow-up was 11 months (ranging from 6 - 17 months). The local control rates after 3, 6, 10 and 15 months were 86.2, 71.4, 60.9 and 50.0% respectively. At the time of writing, ten patients are alive without evidence of recurrence at 11 - 15 months. The 10 patients presented good control of local tumor and no systemic recurrence, and survived throughout the follow-up period. Other 11 patients died of multiple hematogenous metastases 5 - 15 months after brachytherapy. A small amount of local hematoma occurred in 5 patients that involved applicator insertion through the lung. Four patients presented pneumothorax with pulmonary compression of 30% - 40% after the procedure and recovered after drainage. Two patients had minor displacement of radioactive seeds. Severe complications such as massive bleeding and radiation pneumonitis did not occur. So CT-guided 125I brachytherapy is effective and may be safely applied to lung metastasis from hepatocellular carcinoma.

Assessment of Primary Colorectal Cancer Heterogeneity by Using Whole-Tumor Texture Analysis: Contrast-enhanced CT Texture as a Biomarker of 5-year Survival

To determine if computed tomographic (CT) texture features of primary colorectal cancer are related to 5-year overall survival rate. Institutional review board waiver was obtained for this retrospective analysis. Texture features of the entire primary tumor were assessed with contrast material-enhanced staging CT studies obtained in 57 patients as part of an ethically approved study and by using proprietary software. Entropy, uniformity, kurtosis, skewness, and standard deviation of the pixel distribution histogram were derived from CT images without filtration and with filter values corresponding to fine (1.0), medium (1.5, 2.0), and coarse (2.5) textures. Patients were followed up until death and were censored at 5 years if they were still alive. Kaplan-Meier analysis was performed to determine the relationship, if any, between CT texture and 5-year overall survival rate. The Cox proportional hazards model was used to assess independence of texture parameters from stage. Follow-up data were available for 55 of 57 patients. There were eight stage I, 19 stage II, 17 stage III, and 11 stage IV cancers. Fine-texture feature Kaplan-Meier survival plots for entropy, uniformity, kurtosis, skewness, and standard deviation of the pixel distribution histogram were significantly different for tumors above and below each respective threshold receiver operating characteristic (ROC) curve optimal cutoff value (P = .001, P = .018, P = .032, P = .008, and P = .001, respectively), with poorer prognosis for ROC optimal values (a) less than 7.89 for entropy, (b) at least 0.01 for uniformity, (c) less than 2.48 for kurtosis, (d) at least -0.38 for skewness, and (e) less than 61.83 for standard deviation. Multivariate Cox proportional hazards regression analysis showed that each parameter was independent from the stage predictor of overall survival rate (P = .001, P = .009, P = .006, P = .02, and P = .001, respectively). Fine-texture features are associated with poorer 5-year overall survival rate in patients with primary colorectal cancer. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120254/-/DC1.

CT-guided 125I brachytherapy for mediastinal metastatic lymph nodes recurrence from esophageal carcinoma: Effectiveness and safety in 16 patients

ObjectivesTo retrospectively evaluate effectiveness and safety of CT-guided 125I brachytherapy in 16 patients with mediastinal metastatic lymph nodes recurrence from esophageal carcinoma. Materials and methodsSixteen metastatic lymph nodes in 16 patients were percutaneously treated in 19 125I brachytherapy sessions. Each metastatic lymph node was treated with computed tomographic (CT) guidance. Follow-up contrast material-enhanced CT or positron emission tomographic (PET) scans were reviewed and the treatment's effectiveness was evaluated. ResultsMonths are counted from the first time of 125I brachytherapy and the median duration of follow-up was 11 months (range, 5–16 months). The local control rates after 3, 6, 10 and 15 months were 75.0, 50.0, 42.9 and 33.3% respectively. At the time of writing, four patients are alive without evidence of recurrence at 16, 9, 16 and 9 months. The 4 patients presented good control of local tumor and no systemic recurrence, and survived throughout the follow-up period. The other 12 patients died of multiple hematogenous metastases 5–15 months after brachytherapy. A small amount of local hematoma occurred in 2 patients that involved applicator insertion through the lung. Two patients presented pneumothorax with pulmonary compression of 30 and 40% after the procedure and recovered after drainage. One patient had minor displacement of radioactive seeds. Severe complications such as massive bleeding and radiation pneumonitis did not occur. Conclusion125I radioactive seed implantation is effective and may be safely applied to mediastinal metastatic lymph nodes recurrence from esophageal carcinoma.

Combined radio-colour contrast in the examination of ballistic head models

The conventional analysis of ballistic gelatine is performed by transillumination and scanning of 1-cm-thick slices. Previous research demonstrated the advantages of colour and radio contrast in gelatine for computed tomography (CT). The aim of this study was to determine whether this method could be applied to head models in order to facilitate their examination. Four head models of about 14cm in diameter were prepared from two acryl hollow spheres and two polypropylene hollow spheres. Acryl paint was mixed with barium meal and sealed in a thin foil bag which was attached to the gelatine-filled sphere which was covered with about 3-mm-thick silicone. The head models were shot at using 9mm × 19 expanding bullets from 4m distance. The models were examined via multislice CT. The gelatine core was removed; the bullet track was photographed and cut into consecutive slices which were scanned optically. CT images were processed with Corel Photo-Paint. Optical and radiological images were analysed using the AxioVision software. The disruption of the gelatine within the head model was visualised by extensive distribution of paint up to the end of the finest cracks and fissures and along the whole bullet track. CT imaging with excellent radio contrast in the gelatine cracks caused by the temporary cavity allowed for multiplanar reconstruction. We conclude that the combination of colour contrast in gelatine with contrast material-enhanced CT facilitates accurate measurements in ballistic head models.

Preparative Fasting for Contrast-enhanced CT: Reconsideration

To evaluate the evidence on the value of preparative fluid fasting for patients undergoing elective computed tomography (CT) with intravenous administration of contrast material and to survey leading institutions in a number of countries on their current policies in this regard. This study qualified for exempt status by the institutional review board. First, 20 keyword combinations were entered into Medline to ascertain the correlation between fluid ingestion preceding contrast material-enhanced CT and development of aspiration pneumonia. The numbers of patients were summed up to estimate incidence of aspiration pneumonia attributable to ingestion of clear inert fluid before contrast-enhanced CT examination. Second, a multinational survey was conducted about the length of preparative fasting protocols, if any, for fluids and solids that they recommend to patients before elective non-gastrointestinal contrast-enhanced CT. Aspiration was not noted in any of 2001 patients (13 studies in the literature) who underwent contrast-enhanced CT after fluid ingestion. Data were available from 69 (86.3%) of 80 institutions queried (17 Korean, 14 U.S., 11 French, 10 Australian, 10 German, and seven Egyptian hospitals). Two-thirds (14 of 21 [66.7%]) of the French and German hospitals had a no-restriction policy for both fluids and solids, while Australian hospitals had a policy liberal about fluids (no restrictions in eight of 10 [80%]) only. Policies on fluids were variable in Korea, the United States, and Egypt (restrictions of 0-8 hours, 0-4 hours, and 0-6 hours, respectively), as were policies on solids in Korea, the United States, Australia, and Egypt (restrictions of 0-8 hours, 0-6 hours, 0 to 4-6 hours, and 0 hours to overnight, respectively). The length of fasting was longer for solids than for fluids in 20 hospitals. There is little evidence that ingestion of clear inert fluid prior to contrast-enhanced CT is a cause of aspiration pneumonia; the length of fasting is variable in any country, being much longer in some hospitals than in others.

Acute Cholecystitis: Preoperative CT Can Help the Surgeon Consider Conversion from Laparoscopic to Open Cholecystectomy

To establish whether preoperative computed tomographic (CT) findings in patients with acute cholecystitis were associated with conversion from laparoscopic to open cholecystectomy in patients with calculous acute cholecystitis. The study protocol was approved by the local institutional review board, and written informed consent was provided by all patients at enrollment. From 2008 to 2010, all patients admitted to a university medical center with acute calculous cholecystitis and for whom a preoperative contrast material-enhanced CT study was available were prospectively included. Cholecystectomy was always initiated laparoscopically. To identify risk factors for conversion specifically related to acute cholecystitis, CT studies were analyzed according to predefined criteria by two radiologists who were blinded to the patient's conversion status. Associations between conversion and radiologic findings were assessed by using univariate and multivariate logistic models. A total of 108 patients were analyzed (61 men, 47 women; median age, 58 years; age range, 17-88 years). Conversion occurred in 24 (22%) cases. On preoperative CT images, the absence of gallbladder wall enhancement was associated with the presence of gangrenous acute cholecystitis (sensitivity, 73%). The absence of gallbladder wall enhancement (58% and 40% for conversion and nonconversion, respectively; P = .02) and the presence of a gallstone in the gallbladder infundibulum (78% and 22% for conversion and nonconversion, respectively; P = .04) were associated with acute cholecystitis-related conversion in a multivariate analysis. Interobserver agreement for CT study interpretation was very good (median k value, 0.92; range, 0.76-1.00). The absence of gallbladder wall enhancement (associated with the presence of gangrenous acute cholecystitis) and the presence of a gallstone in the gallbladder infundibulum are associated with conversion from laparoscopic to open cholecystectomy.

Assessment of Response to Tyrosine Kinase Inhibitors in Metastatic Renal Cell Cancer: CT Texture as a Predictive Biomarker

To assess changes in tumor computed tomographic (CT) texture after two cycles of treatment with tyrosine kinase inhibitors (TKIs) and to determine if tumor texture correlates with measured time to progression in patients with metastatic renal cell cancer who received TKIs. A waiver of institutional review board approval was obtained for this retrospective analysis. Contrast material-enhanced CT texture parameters were assessed in 39 patients with metastatic renal cell cancer who received a TKI. A total of 87 metastases were analyzed at baseline and after two treatment cycles. Changes in tumor entropy and uniformity were derived with a software algorithm that selectively filters and extracts texture at different scales (fine to coarse detail: 1.0-2.5) and were recorded. Response assessment was also obtained by using response evaluation criteria in solid tumors (RECIST), as well as Choi and modified Choi criteria. The correlation of texture parameters and standard criteria with measured time to progression was assessed by using Kaplan-Meier analysis and a Cox regression model. Statistical significance was set at 5%. Tumor entropy decreased by 3%-45% and uniformity increased by 5%-21% for the different scale values after administration of a TKI. With a threshold change of -2% or less for uniformity at a coarse scale value of 2.5, Kaplan-Meier curves of the proportion of patients without disease progression were significantly different and better than those for standard response assessment (P = .008 vs P = .267, P = .053, and P = .042 for RECIST, Choi, and modified Choi criteria, respectively). Cox regression analysis showed that texture uniformity was an independent predictor of time to progression (odds ratio, 4.02; 95% confidence interval: 1.52, 10.65; P = .005). CT texture analysis reflecting tumor heterogeneity is an independent factor associated with time to progression and has potential as a predictive imaging biomarker of response of metastatic renal cancer to targeted therapy.

Immunoglobulin G4–related Periaortitis and Periarteritis: CT Findings in 17 Patients

To retrospectively evaluate computed tomographic (CT) findings of immunoglobulin G4 (IgG4)-related disease involving the vascular system. This study was approved by the institutional review board, and all patients included had consented to the use of their medical records for the purpose of research. The study consisted of 17 patients (16 men and one woman; age range, 54-86 years). CT findings of IgG4-related periarterial lesions were retrospectively analyzed. Radiopathologic correlations were examined on the basis of surgically resected specimens. A total of 22 periarterial lesions were detected in 17 patients. The lesions were located in the thoracic aorta (n = 4), abdominal aorta to iliac arteries (n = 13), superior mesenteric artery (n = 3), inferior mesenteric artery (n = 1), and splenic artery (n = 1). Radiologically, they were characterized by arterial wall thickening (mean thickness, 11 mm), relatively clear circumscription, possible association with luminal change (mostly dilated and rarely stenotic), exaggerated atherosclerotic change, and homogeneous enhancement at the late phase of contrast material-enhanced CT. Twelve patients (71%) had IgG4-related disease in other organs. Pathologically, diffuse lymphoplasmacytic infiltration, numerous IgG4-positive plasma cells, and irregular fibrosis were noted in the thickened arterial wall, especially at the adventitia. Steroid therapy administered to eight patients rapidly diminished the arterial wall thickening. One patient who did not receive steroid therapy showed spontaneous improvement at follow-up CT. IgG4-related arterial lesions occur mainly in the aorta and its main branches and are radiologically characterized by homogeneous arterial wall thickening corresponding to pathologic features of IgG4-related sclerosing inflammation in the adventitia.

Appropriate Patient Selection at Abdominal Dual-Energy CT Using 80 kV: Relationship between Patient Size, Image Noise, and Image Quality

To determine the computed tomographic (CT) detector configuration, patient size, and image noise limitations that will result in acceptable image quality of 80-kV images obtained at abdominal dual-energy CT. The Institutional Review Board approved this HIPAA-compliant retrospective study from archival material from patients consenting to the use of medical records for research purposes. A retrospective review of contrast material-enhanced abdominal dual-energy CT scans in 116 consecutive patients was performed. Three gastrointestinal radiologists noted detector configuration and graded image quality and artifacts at specified levels-midliver, midpancreas, midkidneys, and terminal ileum-by using two five-point scales. In addition, an organ-specific enhancement-to-noise ratio and background noise were measured in each patient. Patient size was measured by using the longest linear dimension at the level of interest, weight, lean body weight, body mass index, and body surface area. Detector configuration, patient sizes, and image noise levels that resulted in unacceptable image quality and artifact rankings (score of 4 or higher) were determined by using multivariate logistic regression. A 14 × 1.2-mm detector configuration resulted in fewer images with unacceptable quality than did the 64 × 0.6-mm configuration at all anatomic levels (P = .004, .01, and .02 for liver, pancreas, and kidneys, respectively). Image acceptability for the kidneys and ileum was significantly greater than that for the liver for all readers and detector configurations (P < .001). For the 14 × 1.2-mm detector configuration, patient longest linear dimensions yielding acceptable image quality across readers ranged from 34.9 to 35.8 cm at the four anatomic levels. An 80-kV abdominal CT can be performed with appropriate diagnostic quality in a substantial percentage of the population, but it is not recommended beyond the described patient size for each anatomic level. The 14 × 1.2-mm detector configuration should be preferred.