Dual-energy CT iodine overlay improves efficiency of oral contrast leak assessment.

BACKGROUND: Evaluation for gastrointestinal leak is a frequent imaging indication, and dual-energy computed tomography (DECT) with oral or rectally administered contrast can be used to improve efficiency and diagnostic confidence. PURPOSE: To assess the value of the DECT iodine overlay (IO) reconstruction as a stand-alone image set compared to routine CT in assessing oral or rectal contrast leak from the gastrointestinal system. MATERIAL AND METHODS: A blinded, retrospective audit study was performed by three readers who each interpreted 50 studies performed for assessment of oral or rectal contrast leak that were acquired using DECT. Each reader independently assessed both the routine CT images and the images of the reconstructed IO for contrast leak in random order with a six-week "wash-out period" between readings. Clinical follow-up provided the reference standard. Readers recorded the presence/absence of a leak, diagnostic confidence, image quality score, and interpretation time for each image set. RESULTS: Pooled data for overall accuracy in identification of a leak increased from 0.81 (95% confidence interval [CI]=0.74-0.87) for routine CT to 0.91 (95% CI=0.85-0.95) with IO, and the area under the curve (AUC) was significantly higher for IO than routine CT (P = 0.015). Readers required significantly less time to interpret IO than routine CT (median improvement of 12.5 s per image using pooled data; P < 0.001) while maintaining diagnostic confidence and perceived image quality. CONCLUSION: Use of DECT IO reconstructions for identification of oral or rectal contrast leak requires less time to interpret than routine CT with improved accuracy and maintained diagnostic confidence and perceived image quality.

A linguistic approach to the psychosis continuum: (dis)similarities and (dis)continuities in how clinical and non-clinical voice-hearers talk about their voices.

Introduction: "Continuum" approaches to psychosis have generated reports of similarities and differences in voice-hearing in clinical and non-clinical populations at the cohort level, but not typically examined overlap or degrees of difference between groups. Methods: We used a computer-aided linguistic approach to explore reports of voice-hearing by a clinical group (Early Intervention in Psychosis service-users; N = 40) and a non-clinical group (spiritualists; N = 27). We identify semantic categories of terms statistically overused by one group compared with the other, and by each group compared to a control sample of non-voice-hearing interview data (log likelihood (LL) value 6.63+=p < .01; effect size measure: log ratio 1.0+). We consider whether individual values support a continuum model. Results: Notwithstanding significant cohort-level differences, there was considerable continuity in language use. Reports of negative affect were prominent in both groups (p < .01, log ratio: 1.12+). Challenges of cognitive control were also evident in both cohorts, with references to "disengagement" accentuated in service-users (p < .01, log ratio: 1.14+). Conclusion: A corpus linguistic approach to voice-hearing provides new evidence of differences between clinical and non-clinical groups. Variability at the individual level provides substantial evidence of continuity with implications for cognitive mechanisms underlying voice-hearing.

Assessment of magnetic resonance imaging derived fat fraction as a sensitive and reliable predictor of myosteatosis in liver transplant recipients.

BACKGROUND: Measures of skeletal muscle abnormalities are rapidly emerging as independent predictors of outcomes after liver transplantation (LT). We describe a simple, novel assessment of myosteatosis acquired prior to liver transplantation using Magnetic Resonance Imaging (MRI) derived fat fraction. METHODS: A retrospective longitudinal cohort study included clinical and biochemical data from patients who underwent liver transplantation at our institution between Feb 2008 and Aug 2014. Patients transplanted for a diagnosis of hepatocellular carcinoma were excluded from the study. The fat fraction of erector spinae muscles was estimated using MRI at the level where muscle volume was highest, with myosteatosis defined at a cut-off value of 0.8. RESULTS: 180 patients were included. At baseline, those with myosteatosis were, on average, older, more likely to be female, and more likely to receive a multi-organ transplant (p < 0.05). Patients with pre-transplant myosteatosis, as delineated by MRI derived fat fraction, also had increased length of hospital stay. CONCLUSION: This preliminary study suggests myosteatosis, as measured by fat fraction on MRI prior to LT, may be associated with increased graft loss and mortality after transplant.

Combined Qualitative and Quantitative Assessment of Low-Attenuation Renal Lesions Improves Identification of Renal Malignancy on Noncontrast Computed Tomography.

OBJECTIVE: The objective of this study was to assess renal lesions measuring less than 20 Hounsfield units (HU) on noncontrast computed tomography (NCT). METHODS: Twenty-one (18.1%) of 116 consecutive pathologically proven renal cell carcinomas measured less than 20 HU on NCT and were compared with 40 confirmed benign cysts also measuring less than 20 HU. All lesions were assessed qualitatively (heterogeneous or homogenous) by 3 blinded readers and quantitatively with commercially available textural analysis software. Finally, a combined assessment was performed. RESULTS: Qualitative assessment performed well (sensitivity, 76%-90%; specificity, 70%-88%). Quantitative assessment revealed mean positive pixels as having the highest performance (area under the curve, 0.912; sensitivity, 90%; specificity, 80% at a cutoff value of 21). The combined assessment, using the mean positive pixel cutoff, improved the sensitivity (reader 1, 100%; reader 2, 95%; and reader 3, 95%). CONCLUSION: Qualitative and quantitative assessments have relatively good performance, but the combination can nearly eliminate renal cell carcinomas being missed on NCT.

A noise-optimized virtual monoenergetic reconstruction algorithm improves the diagnostic accuracy of late hepatic arterial phase dual-energy CT for the detection of hypervascular liver lesions.

OBJECTIVES: To assess the image quality and diagnostic accuracy of a noise-optimized virtual monoenergetic imaging (VMI+) algorithm compared with standard virtual monoenergetic imaging (VMI) and linearly-blended (M_0.6) reconstructions for the detection of hypervascular liver lesions in dual-energy CT (DECT). METHODS: Thirty patients who underwent clinical liver MRI were prospectively enrolled. Within 60 days of MRI, arterial phase DECT images were acquired on a third-generation dual-source CT and reconstructed with M_0.6, VMI and VMI+ algorithms from 40 to 100 keV in 5-keV intervals. Liver parenchyma and lesion contrast-to-noise-ratios (CNR) were calculated. Two radiologists assessed image quality. Lesion sensitivity, specificity and area under the receiver operating characteristic curves (AUCs) were calculated for the three algorithms with MRI as the reference standard. RESULTS: VMI+ datasets from 40 to 60 keV provided the highest liver parenchyma and lesion CNR (p ≤0.021); 50 keV VMI+ provided the highest subjective image quality (4.40±0.54), significantly higher compared to VMI and M_0.6 (all p <0.001), and the best diagnostic accuracy in < 1-cm diameter lesions (AUC=0.833 vs. 0.777 and 0.749, respectively; p ≤0.003). CONCLUSIONS: 50-keV VMI+ provides superior image quality and diagnostic accuracy for the detection of hypervascular liver lesions with a diameter < 1cm compared to VMI or M_0.6 reconstructions. KEY POINTS: • Low-keV VMI+ are characterized by higher contrast resulting from maximum iodine attenuation. • VMI+ provides superior image quality compared with VMI or M_0.6. • 50-keV_VMI+ provides higher accuracy for the detection of hypervascular liver lesions < 1cm.

Impact of low-kVp scan technique on oral contrast density at abdominopelvic CT.

PURPOSE: To assess quantitative and qualitative effects of kVp on oral contrast density. MATERIALS AND METHODS: Three readers retrospectively reviewed 100 CT scans performed at a range of high- and low-energy settings, independently determining their preferred window and level settings for evaluation of the oral-contrast-opacified bowel. Contrast density was also assessed quantitatively in the stomach, jejunum, and ileum. Subsequently, a range of oral contrast dilutions were imaged at varying kVp's in a commercially available CIRS tissue equivalent phantom model. RESULTS: In the retrospective patient study, mean oral contrast density increased significantly in the ileum compared to the jejunum (455.2 and 308.8 HU, respectively, p < 0.01). Similar findings were seen in patients regardless of patients' weight. Mean oral contrast density was higher on lower-energy scans, requiring more window/level adjustment. An oral contrast iodine concentration of 5.82-7.77 mg I/mL most closely approximated a target oral contrast density of 200 HU. CONCLUSIONS: Oral contrast density is strongly influenced by kVp, supporting use of more dilute oral contrast when using lower-kVp techniques.

Single- and dual-energy CT of the abdomen: comparison of radiation dose and image quality of 2nd and 3rd generation dual-source CT.

OBJECTIVES: To compare single-energy (SECT) and dual-energy (DECT) abdominal CT examinations in matched patient cohorts regarding differences in radiation dose and image quality performed with second- and third-generation dual-source CT (DSCT). METHODS: We retrospectively analysed 200 patients (100 male, 100 female; mean age 61.2 ± 13.5 years, mean body mass index 27.5 ± 3.8 kg/m2) equally divided into four groups matched by gender and body mass index, who had undergone portal venous phase abdominal CT with second-generation (group A, 120-kV-SECT; group B, 80/140-kV-DECT) and third-generation DSCT (group C, 100-kV-SECT; group D, 90/150-kV-DECT). The radiation dose was normalised for 40-cm scan length. Dose-independent figure-of-merit (FOM) contrast-to-noise ratios (CNRs) were calculated for various organs and vessels. Subjective overall image quality and reader confidence were assessed. RESULTS: The effective normalised radiation dose was significantly lower (P < 0.001) in groups C (6.2 ± 2.0 mSv) and D (5.3 ± 1.9 mSv, P = 0.103) compared to groups A (8.8 ± 2.3 mSv) and B (9.7 ± 2.4 mSv, P = 0.102). Dose-independent FOM-CNR peaked for liver, kidney, and portal vein measurements (all P ≤ 0.0285) in group D. Subjective image quality and reader confidence were consistently rated as excellent in all groups (all ≥1.53 out of 5). CONCLUSIONS: With both DSCT generations, abdominal DECT can be routinely performed without radiation dose penalty compared to SECT, while third-generation DSCT shows improved dose efficiency. KEY POINTS: • Dual-source CT (DSCT) allows for single- and dual-energy image acquisition. • Dual-energy acquisition does not increase the radiation dose in abdominal DSCT. • Third-generation DSCT shows improved dose efficiency compared to second-generation DSCT. • Dose-independent figure-of-merit image contrast was highest with third-generation dual-energy DSCT. • Third-generation DSCT shows improved dose efficiency for SECT and DECT.

Limitation of Virtual Noncontrasted Images in Evaluation of a Liver Lesion Status Post Transarterial Chemoembolization.

The authors describe a case of a patient with a solitary hepatocellular carcinoma status post transarterial chemoembolization. Follow-up imaging was performed using dual-energy computed tomography. The study was performed with and without contrast and a virtual noncontrast data set was constructed from the postcontrast images. The evaluation of this patient status post transarterial chemoembolization with virtual noncontrast alone erroneously suggested enhancement and viable tumor. However, examination of true noncontrast images revealed these findings to be due to the subtraction of iodine in Ethiodol within the treated lesion.

Imaging Requirements for Utilization of T2*-Weighted Magnetic Resonance Imaging for Identification of Hepatocellular Carcinoma in Cirrhosis: Effect of Hepatic Iron Content.

PURPOSE: To evaluate the impact of the level of inherent hepatic iron deposition on the ability of multiecho T2*-weighted magnetic resonance imaging (T2*WI) to identify hepatocellular carcinoma. This is relevant to the ancillary features described in the Liver Imaging Reporting and Data System reporting system. METHODS: This retrospective review identified liver transplant patients with a preoperative magnetic resonance imaging at 1.5 T including gradient-recalled echo T2*WI (echo time, 9.5, 19.3, 29.0 milliseconds). A blinded, randomized reading was performed by a single reader of each of the images at each echo time. Hepatic iron content (HIC) was calculated for each participant and compared with the results of the blinded read. RESULTS: Ninety-eight HCCs were identified on explant pathology in 73 participants. Of these, 57 HCCs (58%) were identified on T2*WI. However, no HCCs were visible in participants with HIC < 1.0 mg/g. For participants with HIC > 1.0 mg/g, 57 (88%) of 65 HCCs were visible. CONCLUSIONS: Most of HCCs can be identified on T2*WI without gadolinium; however, performance is significantly affected by background HIC.

Application of an Advanced Image-Based Virtual Monoenergetic Reconstruction of Dual Source Dual-Energy CT Data at Low keV Increases Image Quality for Routine Pancreas Imaging.

PURPOSE: To compare image quality on contrast-enhanced dual-energy computed tomography (DECT) during the pancreatic parenchymal phase of pancreatic masses between linearly-blended simulated 120 kVp images (routine) and advanced image-based virtual monoenergetic reconstructions at 55 keV. METHODS: This was a retrospective evaluation of 24 nonconsecutive adults found to have a focal pancreatic mass on a multiphasic abdominal dual-source DECT (12 adenocarcinoma, 5 neuroendocrine, 7 cystic tumors). For pancreatic-parenchymal phase images, subjects had routine and 55 keV images reconstructed at the time of clinical evaluation. Quantitative evaluation by contrast-to-noise ratio and qualitative evaluations of image quality by (1) direct comparison of image pairs (preference) and (2) blinded assessment of image quality measures based on Likert scores were performed. RESULTS: Mean patient weight was 205.8 ± 26.6 lbs. Mean pancreatic lesion contrast-to-noise ratio was significantly higher at 55 keV (6.8 ± 4.1) compared to the routine image series (5.8 ± 3.8; P = 0.0002). All 3 readers preferred the 55-keV images over routine blended images in 70.1% to 95.8% of cases. No significant differences were observed for subjective sharpness of the mass, visualization of internal mass structures, or image noise. CONCLUSIONS: Use of a single advanced image-based virtual monoenergetic reconstruction at 55 keV in pancreatic DECT showed improved objective image quality and reader preference compared to routine images. As this image reconstruction can be incorporated into the scan protocol, this technique should be considered for routine clinical use.

Incidence of intravenous contrast extravasation: increased risk for patients with deep brachial catheter placement from the emergency department.

Deep brachial intravenous catheter (IV) placement can be performed in emergency department patients with difficult vascular access, but the safety of deep brachial IV for iodinated contrast administration has not been assessed. This study compares the relative risk for extravasation of deep brachial IV compared with antecubital IV during power injected computed tomography (CT) examinations. A departmental practice quality improvement was performed to assess the rate of IV extravasation for all CT examinations during a 1 year period. De-identified data was analyzed with a waiver of informed consent to identify the rate and relative risk of iodinated contrast extravasation by catheter type. A total of 10,750 injections were performed, with 82 extravasation events (0.8 %). There were 51 extravasations of antecubital IV from approximately 8,599 placed (0.6 %). For 123 deep brachial IV placed, there were eight extravasations (6.5 %). The relative risk of a deep brachial IV extravasation was 9.4 compared to 0.4 for antecubital placement. Deep brachial IV demonstrated a markedly higher rate of contrast extravasation than antecubital IV. For power injected iodinated contrast administration, it is recommended to avoid the use of deep brachial IV whenever possible.

Iodine quantification of renal lesions: Preliminary results using spectral-based material extraction on photon-counting CT.

Objectives: To assess the range of quantitative iodine values in renal cysts (RC) (with a few renal neoplasms [RNs] as a comparison) to develop an expected range of values for RC that can be used in future studies for their differentiation. Material and Methods: Consecutive patients (n = 140) with renal lesions who had undergone abdominal examination on a clinical photon-counting computed tomography (PCCT) were retrospectively included. Automated iodine quantification maps were reconstructed, and region of interest (ROI) measurements of iodine concentration (IC) (mg/cm3) were performed on whole renal lesions. In addition, for heterogeneous lesions, a secondary ROI was placed on the area most suspicious for malignancy. The discriminatory values of minimum, maximum, mean, and standard deviation for IC were compared using simple logistic regression and receiver operating characteristic curves (area under the curve [AUC]). Results: A total of 259 renal lesions (243 RC and 16 RN) were analyzed. There were significant differences between RC and RN for all IC measures with the best-performing metrics being mean and maximum IC of the entire lesion ROI (AUC 0.912 and 0.917, respectively) but also mean and minimum IC of the most suspicious area in heterogeneous lesions (AUC 0.983 and 0.992, respectively). Most RC fell within a range of low measured iodine values although a few had higher values. Conclusion: Automated iodine quantification maps reconstructed from clinical PCCT have a high diagnostic ability to differentiate RCs and neoplasms. The data from this pilot study can be used to help establish quantitative values for clinical differentiation of renal lesions.

Improved performance of SPECT-CT In-111 capromab pendetide by correlation with diffusion-weighted magnetic resonance imaging for identifying metastatic pelvic lymphadenopathy in prostate cancer.

PURPOSE: To preliminarily evaluate the potential for an improvement in diagnostic performance by a combined interpretation of In-111 capromab pendetide single photon emission computed tomography (SPECT) including computed tomography (CT) image fusion with magnetic resonance diffusion-weighted imaging (MR-DWI) for identifying prostate cancer in pelvic lymph nodes thru correlation with histopathology. MATERIALS AND METHODS: This institutional approved, retrospective study identified patients with available histopathology of lymph nodes removed at the time of radical prostatectomy and who had undergone staging with In-111 capromab pendetide SPECT-CT and/or pelvic MRI (including DWI). The performance of In-111 capromab pendetide SPECT for identifying malignant lymph nodes was assessed. Subsequently, a combined reading of In-111 capromab pendetide SPECT and prostate MRI with DWI was performed and the performance assessed. RESULTS: 18 patients underwent In-111 capromab pendetide SPECT-CT. Of these, 12 patients had also undergone imaging with MR-DWI. In-111 capromab pendetide SPECT-CT had a sensitivity of 40.0% and specificity of 96.7% for identification of malignant lymph nodes. However, In-111 capromab pendetide SPECT-CT combined with MRI with DWI had a sensitivity of 88.9% and specificity of 98.5%. CONCLUSIONS: The addition of MR-DWI to the interpretation of In-111 capromab pendetide SPECT-CT may increase the sensitivity for detecting malignant lymph nodes in prostate cancer. Future prospective evaluation of combined In-111 capromab pendetide SPECT-CT and MR-DWI is indicated and may improve clinical evaluation of nodal disease in prostate cancer.

Utility of quantitative MRI metrics for assessment of stage and grade of urothelial carcinoma of the bladder: preliminary results.

OBJECTIVE: The purpose of this study was to assess associations between quantitative MRI metrics and pathologic indicators of aggressiveness of urothelial carcinoma of the bladder. MATERIALS AND METHODS: In this retrospective biinstitutional study, 37 patients (28 men and nine women; mean age, 73 ± 12 years) who underwent pelvic MRI including diffusion-weighted imaging (b values 0, 400, and 800 s/mm(2)) and T2-weighted imaging before transurethral resection or cystectomy for urothelial carcinoma of the bladder were identified. Tumor diameter (measured on T2-weighted imaging), normalized T2 signal intensity (to muscle; hereafter labeled normalized T2) and apparent diffusion coefficient (ADC) were measured for all tumors. Mann-Whitney test and receiver operating characteristic analyses were used to identify associations between these metrics and histopathologic tumor stage and grade. RESULTS: Thirty-seven tumors were assessed (mean size, 35 ± 23 mm; range 8-88 mm). At histopathologic analysis, 16 of 37 (43%) tumors were stage T2 or greater and 21 of 37 (57%) were stage T1 or lower, whereas 34 of 37 (92%) were high grade and three of 37 (8%) were low grade. High-stage (≥ T2) tumors showed greater tumor diameter, lower normalized T2, and lower ADC (p = 0.005-0.032) than low-stage (≤ T1) tumors. Tumor diameter and ADC were significant independent predictors of stage (p ≤ 0.043), with their combination giving an area-under the-curve (AUC) of 0.804. High-grade tumors showed significantly lower ADC (p = 0.023) but no significant difference in tumor diameter or normalized T2 (p = 0.201-0.559). AUC for differentiating low- and high-grade tumors was higher for ADC (0.902) than for tumor diameter (0.603) or normalized T2 (0.725). CONCLUSION: A combination of size and quantitative MRI metrics can potentially be used as markers of stage and grade of bladder cancer.

Physician preference between low-dose computed tomography with a sinogram-affirmed iterative reconstruction algorithm and routine-dose computed tomography with filtered back projection in abdominopelvic imaging.

OBJECTIVE: The aim of this study was to directly compare the preference between low-dose sinogram-affirmed iterative reconstruction (SAFIRE) and routine filtered back projection (FBP) abdominopelvic computed tomography (CT). METHODS: A retrospective review identified 41 subjects who had undergone 2 different CT examinations at different times (a CT with reduced radiation dose SAFIRE and also a CT with routine-dose FBP). Radiation dose, patient size, and image noise were recorded. Two independent readers assessed the paired CT studies for preference in image quality in regard to 3 clinically relevant diagnostic endpoints (bowel pathology, biliary pathology, and general purpose). RESULTS: Radiation dose was significantly lower for SAFIRE (mean, 7.6 mGy; range, 4.1-15.4 mGy) than FBP (12.9 mGy; 6.7-31.6 mGy) (P < 0.001). Sinogram-affirmed iterative reconstruction was preferred for the general purpose and bowel evaluations, particularly when the level of radiation dose reduction was less than 33%. The preference for interpretation of the biliary system was equivocal, especially when the level of radiation reduction was increased greater than 33%. Filtered back projection was preferred when SAFIRE had a radiation reduction from FBP of greater than 50%. CONCLUSIONS: For abdominopelvic CT, low-dose CT with SAFIRE may produce preferred image quality over FBP up to levels of 50% dose reduction.

Use of dual energy CT to identify gastrointestinal anastomotic leak by assessment of percutaneous drain contents.

Anastomotic leakage is a feared complication of many different types of gastrointestinal surgery. It is important to identify patients with leaks early because sepsis may develop quickly. Suspected leaks are typically confirmed by either fluoroscopy or computed tomography with oral contrast. This article presents a novel method to confirm the presence of a gastrointestinal anastomotic leak when standard imaging and clinical presentation are ambiguous.

Quantitative myocardial T2 mapping adds value to Japanese circulation society diagnostic criteria for active cardiac sarcoidosis.

Noninvasive identification of active myocardial inflammation in patients with cardiac sarcoidosis plays a key role in management but remains elusive. T2 mapping is a proposed solution, but the added value of quantitative myocardial T2 mapping for active cardiac sarcoidosis is unknown. Retrospective cohort analysis of 56 sequential patients with biopsy-confirmed extracardiac sarcoidosis who underwent cardiac MRI for myocardial T2 mapping. The presence or absence of active myocardial inflammation in patients with CS was defined using a modified Japanese circulation society criteria within one month of MRI. Myocardial T2 values were obtained for the 16 standard American Heart Association left ventricular segments. The best model was selected using logistic regression. Receiver operating characteristic curves and dominance analysis were used to evaluate the diagnostic performance and variable importance. Of the 56 sarcoidosis patients included, 14 met criteria for active myocardial inflammation. Mean basal T2 value was the best performing model for the diagnosis of active myocardial inflammation in CS patients (pR2 = 0.493, AUC = 0.918, 95% CI 0.835-1). Mean basal T2 value > 50.8 ms was the most accurate threshold (accuracy = 0.911). Mean basal T2 value + JCS criteria was significantly more accurate than JCS criteria alone (AUC = 0.981 vs. 0.887, p = 0.017). Quantitative regional T2 values are independent predictors of active myocardial inflammation in CS and may add additional discriminatory capability to JCS criteria for active disease.

Preliminary evaluation of ultra-high pitch computed tomography enterography.

BACKGROUND: CT enterography (CTE) is a valuable tool in the management of patients with inflammatory bowel disease. Reducing imaging time, reduced motion artifacts, and decreased radiation exposure are important goals for optimizing CTE examinations. PURPOSE: To assess the potential impact of new CT technology (ultra-high pitch CTE) for the ability to reduce scan time and also potentially reduce radiation exposure while maintaining image quality. MATERIAL AND METHODS: This retrospective study compared 13 patients who underwent ultra-high pitch CTE with 25 patients who underwent routine CTE on the same CT scanner with identical radiation emission settings. Total scan time and radiation exposure were recorded for each patient. Image quality was assessed by measurement of image noise and also qualitatively by two independent observers. RESULTS: Total scan time was significantly lower for patients who underwent ultra-high pitch CTE (2.1 s ± 0.2) than by routine CTE (18.6 s ± 0.9) (P < 0.0001). The mean radiation exposure for ultra-high pitch CTE was also significantly lower (10.1 mGy ± 1.0) than routine CTE (15.8 mGy ± 4.5) (P < 0.0001). No significant difference in image noise was found between ultra-high pitch CTE (16.0 HU ± 2.5) and routine CTE (15.5 HU ± 3.7) (P > 0.74). There was also no significant difference in image quality noted by either of the two readers. CONCLUSION: Ultra-high pitch CTE can be performed more rapidly than standard CTE and offers the potential for radiation exposure reduction while maintaining image quality.

Use of novel photon - counting detector CT for diagnosis of bowel infarction.

A 75 year old male with a history of thoraco-abdominal surgery presented with acute onset epigastric pain. CT of the abdomen and pelvis with contrast performed on a novel photon-counting detector CT demonstrated dilated loops of small bowel herniating into the thoracic cavity through a defect in the left hemidiaphragm. On conventional CT reconstructions, the bowel wall demonstrated a thin rim of hyper-density which could have been interpreted as normal mucosal enhancement in viable bowel. However, spectral-imaging data including the iodine map revealed a complete lack of enhancement within the herniated loops of bowel compatible with infarction. With the added diagnostic information, the patient was taken rapidly to surgery for small bowel resection, with good outcome.

Multi-Center Follow-up Study to Develop a Classification System Which Differentiates Mucinous Cystic Neoplasm of the Liver and Benign Hepatic Cyst Using Machine Learning.

RATIONALE AND OBJECTIVES: To date, no clinically useful classification system has been developed for reliably differentiating mucinous cystic neoplasm (MCN) from a benign hepatic cyst (BHC) in the liver. The objective was to use machine learning and a multi-center study design to develop and assess the performance of a novel classification system for predicting whether a hepatic cystic lesion represents MCN or BHC. MATERIALS AND METHODS: A multi-center cohort study identified 154 surgically resected hepatic cystic lesions in 154 subjects which were pathologic confirmed as MCN (43) or BHC (111). Readers at each institution recorded seven pre-determined imaging features previously identified as potential differentiating features from prior publications. The contribution of each of these features to differentiating MCN from BHC was assessed by machine learning to develop an optimal classification system. RESULTS: Although several of the assessed imaging features demonstrated statistical significance, only 3 imaging features were found by machine learning to significantly contribute to a potential classification system: (1) solid enhancing nodule (2) all septations arising from an external macro-lobulation (3) whether the lesion was solitary or one of multiple cystic liver lesions. The optimal classification system had only four categories and correctly identified 144/154 lesion (93.5%). CONCLUSION: This multi-center follow-up study was able to use machine learning to develop a highly accurate classification system for differentiation of hepatic MCN from BHC, which could be readily applied to clinical practice.