Radiologic Imaging of Traumatic Bowel and Mesenteric Injuries: A Comprehensive Up-to-Date Review.

Diagnosing bowel and mesenteric trauma poses a significant challenge to radiologists. Although these injuries are relatively rare, immediate laparotomy may be indicated when they occur. Delayed diagnosis and treatment are associated with increased morbidity and mortality; therefore, timely and accurate management is essential. Additionally, employing strategies to differentiate between major injuries requiring surgical intervention and minor injuries considered manageable via non-operative management is important. Bowel and mesenteric injuries are among the most frequently overlooked injuries on trauma abdominal computed tomography (CT), with up to 40% of confirmed surgical bowel and mesenteric injuries not reported prior to operative treatment. This high percentage of falsely negative preoperative diagnoses may be due to several factors, including the relative rarity of these injuries, subtle and non-specific appearances on CT, and limited awareness of the injuries among radiologists. To improve the awareness and diagnosis of bowel and mesenteric injuries, this article provides an overview of the injuries most often encountered, imaging evaluation, CT appearances, and diagnostic pearls and pitfalls. Enhanced diagnostic imaging awareness will improve the preoperative diagnostic yield, which will save time, money, and lives.

Role of Dedicated Subspecialized Radiologists in Multidisciplinary Team Discussions on Lower Gastrointestinal Tract Cancers.

OBJECTIVE: To determine the impact of dedicated subspecialized radiologists in multidisciplinary team (MDT) discussions on the management of lower gastrointestinal (GI) tract malignancies. MATERIALS AND METHODS: We retrospectively analyzed the data of 244 patients (mean age ± standard deviation, 61.7 ± 11.9 years) referred to MDT discussions 249 times (i.e., 249 cases, as five patients were discussed twice for different issues) for lower GI tract malignancy including colorectal cancer, small bowel cancer, GI stromal tumor, and GI neuroendocrine tumor between April 2018 and June 2021 in a prospective database. Before the MDT discussions, dedicated GI radiologists reviewed all imaging studies again besides routine clinical reading. The referring clinician's initial diagnosis, initial treatment plan, change in radiologic interpretation compared with the initial radiology report, and the MDT's consensus recommendations for treatment were collected and compared. Factors associated with changes in treatment plans and the implementation of MDT decisions were analyzed. RESULTS: Of the 249 cases, radiologic interpretation was changed in 73 cases (29.3%) after a review by dedicated GI radiologists, with 78.1% (57/73) resulting in changes in the treatment plan. The treatment plan was changed in 92 cases (36.9%), and the rate of change in the treatment plan was significantly higher in cases with changes in radiologic interpretation than in those without (78.1% [57/73] vs. 19.9% [35/176], p < 0.001). Follow-up records of patients showed that 91.2% (227/249) of MDT recommendations for treatment were implemented. Multiple logistic regression analysis revealed that the nonsurgical approach (vs. surgical approach) decided through MDT discussion was a significant factor for patients being managed differently than the MDT recommendations (Odds ratio, 4.48; p = 0.017). CONCLUSION: MDT discussion involving additional review of radiology examinations by dedicated GI radiologists resulted in a change in the treatment plan in 36.9% of cases. Changes in treatment plans were significantly associated with changes in radiologic interpretation.

The feasibility of deep learning-based synthetic contrast-enhanced CT from nonenhanced CT in emergency department patients with acute abdominal pain.

Our objective was to investigate the feasibility of deep learning-based synthetic contrast-enhanced CT (DL-SCE-CT) from nonenhanced CT (NECT) in patients who visited the emergency department (ED) with acute abdominal pain (AAP). We trained an algorithm generating DL-SCE-CT using NECT with paired precontrast/postcontrast images. For clinical application, 353 patients from three institutions who visited the ED with AAP were included. Six reviewers (experienced radiologists, ER1-3; training radiologists, TR1-3) made diagnostic and disposition decisions using NECT alone and then with NECT and DL-SCE-CT together. The radiologists' confidence in decisions was graded using a 5-point scale. The diagnostic accuracy using DL-SCE-CT improved in three radiologists (50%, P = 0.023, 0.012, < 0.001, especially in 2/3 of TRs). The confidence of diagnosis and disposition improved significantly in five radiologists (83.3%, P < 0.001). Particularly, in subgroups with underlying malignancy and miscellaneous medical conditions (MMCs) and in CT-negative cases, more radiologists reported increased confidence in diagnosis (83.3% [5/6], 100.0% [6/6], and 83.3% [5/6], respectively) and disposition (66.7% [4/6], 83.3% [5/6] and 100% [6/6], respectively). In conclusion, DL-SCE-CT enhances the accuracy and confidence of diagnosis and disposition regarding patients with AAP in the ED, especially for less experienced radiologists, in CT-negative cases, and in certain disease subgroups with underlying malignancy and MMCs.

Can endoscopic ultrasonography (EUS) improve the accuracy of clinical T staging by computed tomography (CT) for gastric cancer?

INTRODUCTION: With the introduction of new therapeutic options for gastric cancer treatment, more precise preoperative staging of gastric cancer is needed. The purpose of this study was to evaluate the role of endoscopic ultrasonography (EUS) for improving the accuracy of clinical T staging by computed tomography (CT) for gastric cancer. MATERIALS AND METHODS: A total of 2636 patients underwent stomach protocol CT (S-CT) and EUS, followed by gastrectomy for primary gastric adenocarcinoma between September 2012 and February 2018 at Seoul National University Hospital. The results of preoperative S-CT and EUS were compared to the postoperative pathologic staging. RESULTS: The overall accuracy of S-CT and EUS for T staging were 69.4% and 70.4%, respectively. When T staging was divided into T1-2 and T3-4 for clinically advanced gastric cancer (AGC), the positive predictive value for T3-4 using S-CT, EUS, and a combination of both modalities was 73.8%, 79.3%, and 85.6%, respectively. In 114 cases of indeterminate lesions between cT1 and cT2 by S-CT, EUS had a better prediction rate than the final decision based on endoscopy or the agreement between the two experts (Match rate: EUS vs. final decision, 69.3% vs. 58.8%). CONCLUSION: EUS can be a complementary diagnostic tool to clinical T staging of gastric cancer by CT for selecting T3-4 lesion.

Coronary Artery Lumen Segmentation Using Location-Adaptive Threshold in Coronary Computed Tomographic Angiography: A Proof-of-Concept.

OBJECTIVE: To compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS). MATERIALS AND METHODS: The Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements. RESULTS: Lumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm³; 95% confidence interval [CI], 4.9-24.3 mm³); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, -0.7 mm³; 95% CI, -9.1-7.7 mm³). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm²; 95% CI, 0.89-1.25 mm²) but not in the larger lumen area group (mean of difference, -0.07 mm²; 95% CI, -0.22-0.08 mm²). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm²; 95% CI, 0.27-0.65 mm²) than in that of IVUS and SATM (1.53 mm²; 95% CI, 1.27-1.79 mm²). CONCLUSION: SATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM.

[Analysis of the Rate of Discrepancy between Preliminary Reports by Radiology Residents and Final Reports by Certified Radiologists for Emergency Radiology Studies in a University Hospital]. / 대학병원 응급 영상검사에서 영상의학과 ì „ê³µì˜ ê°€íŒë ê³¼ ì „ë¬¸ì˜ ìµœì¢ íŒë ê°„ì˜ 불일치 ë°œìƒë¥ ë¶„ì„.

Purpose: In the adult emergency department of a university hospital, we investigated the frequency of major discrepancies between the preliminary reports by radiology residents and the final reports by certified radiologists. Materials and Methods: Based on CT and MRI scans obtained between December 2016 and November 2019, we selected cases with diagnoses or treatment plans that could be changed due to discrepancies between preliminary and final reports and classified them by the type of discrepancy. We also examined the distributions of the major discrepancies and stratified them by residents' working time zone, experience, and subspecialty. Results: Based on the 72137 preliminary reports evaluated, 1348 tests (1.9%) showed major discrepancies. Most of the major discrepancies were false negatives (72.0%), followed by misdiagnosis (26.3%) and false positives (1.7%). Acute findings (87.2%) were more common than non-acute findings (12.8%). The major discrepancy rate increased toward the second half of the 24-hour shift, with the highest rate of 2.9% occurring between 2 am and 4 am. The major discrepancy rate did not vary with experience, and it varied from 0.6% to 4.5% for each subspecialty. Conclusion: The major discrepancy rate was less than 2%, and it increased with longer working hours during a 24-hour shift.

Normal and Abnormal Postoperative Imaging Findings after Gastric Oncologic and Bariatric Surgery.

Surgical resection remains the primary choice of treatment and the only potentially curative option for gastric carcinoma, and is increasingly performed laparoscopically. Gastric resection represents a challenging procedure, with a significant morbidity and non-negligible postoperative mortality. The interpretation of imaging after gastric surgery can be challenging due to significant modifications of the normal anatomy. After the surgery, the familiarity with expected imaging appearances is crucial for diagnosis and appropriate management of potentially life-threatening complications in patients who underwent gastric surgery. We review various surgical techniques used in gastric surgery and describe fluoroscopic and cross-sectional imaging appearances of normal postoperative anatomic changes as well as early and late complications after gastric surgery.

Infected cyst in patients with autosomal dominant polycystic kidney disease: Analysis of computed tomographic and ultrasonographic imaging features.

PURPOSE: To investigate the imaging features of cyst infection in autosomal dominant polycystic kidney disease (ADPKD) patients using computed tomography (CT) and ultrasonography (US). MATERIALS & METHODS: The institutional review board approved this retrospective study. Fifty-one episodes with proven cyst infection in forty-three ADPKD patients were included. Two experienced abdominal radiologists reviewed CT and US images and evaluated the following imaging features in consensus: cyst size, location, cyst shape, intracystic attenuation, intracystic echogenicity, intracystic heterogeneity, wall thickness, the presence of fluid-fluid level, septation, intracystic gas, pericystic fat infiltration, and pericystic hyperemia. Intracystic attenuation was measured for all infected cysts and two presumed normal cysts and compared using the Wilcoxon rank-sum test. RESULTS: On CT scans, the median size of infected cysts was 5.5 cm (range: 2.3-18.8 cm) and 46 of 51 (90.2%) infected cysts were located in the subcapsular region. Most (48 of 51, 94.1%) infected cysts showed lobulated, focal bulging or irregular shape. Discernible wall thickening (84.1%) was the most frequently found imaging feature of infected cysts followed by relatively higher intracystic attenuation compared to normal cysts (79.1%) and pericystic fat infiltration (52.9%). Fluid/fluid level was found in 3 of 51 (5.9%) infected cysts and intracystic gas was found in 3 of 51 (5.9%) infected cysts, respectively. For hepatic cysts, 11 of 14 (78.6%) infected cysts showed pericystic hyperemia. Intracystic attenuation was significantly higher in infected cysts (median; 19.0 HU) than in presumed normal cysts (median; 8.5 HU) (P<0.001), and exceeded 25 HU in 18 (35.3%) of 51 infected cysts. Among the 41 infected cysts for which US images were available, 35 (85.1%) showed heterogeneous echogenicity. CONCLUSION: Minute imaging features such as minimal wall thickening or relatively high attenuation compared to normal cysts would be helpful to detect infected cysts in ADPKD patients.

Sub-millisievert CT colonography: effect of knowledge-based iterative reconstruction on the detection of colonic polyps.

OBJECTIVES: To assess the feasibility of ultra-low dose computed tomography colonography (CTC) using knowledge-based iterative reconstruction (IR) and to determine its effect on polyp detection. METHODS: Forty-nine prospectively-enrolled patients underwent ultra-low dose CTC in the supine (100 kVp/20 mAs) and prone positions (80 kVp/20 mAs), followed by same-day colonoscopy. Thereafter, images were reconstructed using filtered back projection (FBP) and knowledge-based IR (IMR; Philips Healthcare, Best, Netherlands) algorithms. Effective radiation dose of CTC was recorded. Pooled per-polyp sensitivity and positive predictive value of three radiologists was analysed and compared between FBP and IMR. Image quality was assessed on a five-point scale and image noise was recorded using standard deviations. RESULTS: Mean effective radiation dose of ultra-low dose CTC was 0.90 ± 0.06 mSv. Eighty-nine polyps were detected on colonoscopy (mean, 8.5 ± 4.7 mm). The pooled per-polyp sensitivity for polyps 6.0-9.9 mm (n = 22) on CTC reconstructed with IMR (36/66, 54.5%) was not significantly different with that using FBP algorithm (34/66, 51.5%) (p = 0.414). For polyps ≥10 mm (n = 35), however, the pooled per-polyp sensitivity on CTC with IMR (73/105, 69.5%) was significantly higher than that with FBP (55/105, 52.4%) (p < 0.001). In particular, the difference of per-polyp sensitivity was statistically significant in intermediate (p = 0.014) and novice (p = 0.003) reviewers. Furthermore, mean image noise of IMR (8.4 ± 6.2 HU) was significantly lower than that of FBP (37.5 ± 13.9 HU) (p < 0.001) and image quality with IMR was significantly better than with FBP in all evaluated segments in all reviewers (all ps < 0.001). CONCLUSIONS: Sub-mSv CTC reconstructed with IMR was feasible for the detection of clinically significant polyps, demonstrating 70% per-polyp sensitivity of polyps ≥10 mm, while allowing significant noise reduction and improvement in image quality compared with FBP reconstruction. KEY POINTS: • Sub-mSv CTC using IMR demonstrated 70% per-polyp sensitivity for polyps ≥10 mm. • CTC using IMR significantly outperformed CTC reconstructed with FBP. • IMR allows significantly more noise reduction and improvement in image quality than FBP.

Frequency, outcome, and risk factors of contrast media extravasation in 142,651 intravenous contrast-enhanced CT scans.

OBJECTIVE: To evaluate the frequency, outcome, and risk factors of intravenous contrast media (CM) extravasation during contrast-enhanced CT scans in a large population. METHODS: After institutional review board approval, 142,651 patients (72,976 males and 69,675 females; mean age, 59.9 ± 13.0 years) who underwent contrast-enhanced CT scans with intravenous CM between January 2015 and April 2017 were retrospectively included. The frequency of CM extravasations and their clinical outcomes were investigated. Risk factors of CM extravasation were evaluated using logistic regression with generalized estimating equation analyses. In addition, the frequency and risk factors of large-volume (≥100 ml) CM extravasation were also investigated. RESULTS: CM extravasation occurred in 0.23% (321/142,651) of patients, all of which were of mild degree and resolved without any sequelae through conservative management. Multivariate analysis revealed that female gender [odds ratio (OR) = 1.61; p < 0.001], 60 < age ≤ 70 years (OR = 1.71; p = 0.004) or age > 70 years (OR = 2.49; p < 0.001), patients in general wards (OR = 2.71; p < 0.001) or ICUs (OR = 4.76; p < 0.001), 9.4 < CM viscosity ≤ 10.0 (OR = 1.65; p = 0.015), 10.0 < CM viscosity ≤ 10.6 (OR = 1.60; p = 0.002), and CM viscosity > 16.0 (OR = 2.55, p < 0.001) were independent risk factors for CM extravasation. CONCLUSION: CM extravasation during contrast-enhanced CT scans was uncommon with no substantial clinical consequences. Several risk factors that may have the potential to reduce the occurrence of CM extravasation were identified. KEY POINTS: • The observed frequency of contrast media extravasation during contrast-enhanced CT scans was 0.23% (321/142,651). • Significant risk factors for contrast media extravasation were female gender, age older than 60 years, patients in general wards or ICUs, and the viscosity of contrast media greater than 9.4 mPa∙s. • The main preventive action for contrast media extravasation would be to lower the viscosity of contrast media.

Critical Test Result Notification via Mobile Phone-Based Automated Text Message System in the Radiologic Field: Single Institutional Experience.

PURPOSE: To investigate the feasibility of sharing critical test result (CTR) notifications (CTRNs) via automated text messaging. MATERIALS AND METHODS: CTRNs via automated text messaging was used to notify physicians of CTRs in a tertiary hospital with 1,786 beds. From June 2016 to September 2016, notifications for 545 CTRs were given via a CTRN system. Among them, 490 CTRs (292 male and 198 female patients; mean age, 53.6 years old [range, 1-88]) were included in analysis. CTR levels (CTRLs) were assigned to four categories (CTRL1 to CTRL3 and unclassified) when reported, and reclassified into three CTRLs according to their clinical relevance and urgency. Response time was defined as time lapse between CTR reporting and documentation by physicians. Analysis of variance was performed to compare response times according to CTRLs and patients' location. RESULTS: Corresponding actions were taken in 404 of 490 cases (82.4%) without any delayed CTRN-related morbidity. There were 15 CTRL1 (3.1%), 50 CTRL2 (10.2%), 112 CTRL3 (22.9%) cases, and the remaining 313 CTRL cases were unclassified. After reclassification, CTRL1, CTRL2, and CTRL3 were 81 (16.5%), 177 (36.1%), and 232 cases (47.3%), respectively. Response time of reclassified CTRL3 was significantly longer than that of reclassified CTRL1 (median 23.0, [interquartile range 2.0-133.5] hours versus 4.0 [0.0-22.0] hours; P < .001). Response time of outpatient cases (80.0 [6.0 to 157.0] hours) was significantly longer (P < .001) than those of inpatient (3.0 [0.0-16.0]) and emergency department cases (5.0 [1.0-21.0]). CONCLUSION: Automated text messaging could be a feasible option for CTRNs in the radiologic field. Further large-scale investigations regarding efficiency of this system are warranted.

Preoperative tumor restaging and resectability assessment of gastric cancers after chemotherapy: diagnostic accuracy of MDCT using new staging criteria.

PURPOSE: To evaluate the diagnostic performance of preoperative MDCT for tumor restaging and determination of resectability in gastric cancers after chemotherapy using new staging criteria. METHODS: This retrospective study was approved by our institutional review board and the requirement for informed consent was waived. Thirty-seven patients with initially unresectable gastric cancers who had received chemotherapy followed by surgery were included. Two independent radiologists reviewed preoperative MDCT images to determine the TNM staging and rate the overall likelihood of resectability using a 5-point scale (5: definitely unresectable, 1: definitely resectable). New post-chemotherapy MDCT criteria do not use non-enhancing perigastric infiltrations, non-enhancing lymph nodes (LNs), and subtle remaining infiltrations after marked decrease in the size of distant metastases for T, N, and M upstaging, respectively. Discrepancies in TNM staging were resolved by a third reviewer. The diagnostic performances of MDCT were assessed using pathologic results or operation records as reference standards. RESULTS: For predicting resectability, the areas under the ROC curve were 0.885 and 0.882 (95% CIs 0.737-0.966 and 0.733-0.964) in reviewers 1 and 2, respectively, with substantial inter-reader agreement (weighted κ = 0.689). Sensitivities and specificities of MDCT for tumor restaging on a consensus review were 80.0% (4/5) and 100% (29/29) for T4b, 35.3% (6/17) and 81.3% (13/16) for N-positive, and 63.6% (7/11) and 100% (26/26) for M1, respectively. CONCLUSIONS: For gastric cancers after chemotherapy, new MDCT criteria demonstrated high specificities for T4b and M-staging and good performances to predict resectability before conversion surgery.

One-mSv CT colonography: Effect of different iterative reconstruction algorithms on radiologists' performance.

PURPOSE: To analyze the effect of different reconstruction algorithms on image noise and radiologists' performance at ultra-low dose CT colonography (CTC) in human subjects. MATERIALS AND METHODS: This retrospective study had institutional review board approval, with waiver of the need to obtain informed consent. CTC and subsequent colonoscopy were performed at the same day in 28 patients. CTC was scanned at the supine/prone positions using 120/100kVp and fixed 10mAs, and reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based IR (Veo) algorithms. Size-specific dose estimates (SSDE) and effective radiation doses were recorded. Image noise was compared among the three datasets using repeated measures analysis of variance (ANOVA). Per-polyp sensitivity and figure-of-merits were compared among the datasets using the McNemar test and jackknife alternative free-response receiver operating characteristic (JAFROC) analysis, respectively, by one novice and one expert reviewer in CTC. RESULTS: Mean SSDE and effective radiation dose of CTC were 1.732mGy and 1.002mSv, respectively. Mean image noise at supine/prone position datasets was significantly lowest with Veo (17.2/13.3), followed by ASIR (52.4/38.9) and FBP (69.9/50.8) (P<0.0001). Forty-two polyps in 25 patients were reference polyps. For both readers, per-polyp sensitivity of all 42 polyps was highest with Veo reconstruction (81.0%, 64.3%), followed by ASIR (73.8%, 54.8%) and FBP (57.1%, 50.0%) with statistical significance between Veo and FBP for reader 1 (P=0.002). JAFROC analysis revealed that the figure-of-merit for the detection of polyps was highest with Veo (0.917, 0.786), followed by ASIR (0.881, 0.750) and FBP (0.750, 0.746) with statistical significances between Veo or ASIR and FBP for reader 1 (P<0.05). CONCLUSION: One-mSv CTC was not feasible using the standard FBP algorithm. However, diagnostic performance expressed as per-polyp sensitivity and figures-of-merit can be improved with the application of IR algorithms, particularly Veo.

Differentiation of intrahepatic mass-forming cholangiocarcinoma from hepatocellular carcinoma on gadoxetic acid-enhanced liver MR imaging.

OBJECTIVES: To determine the different imaging features of intrahepatic mass-forming cholangiocarcinoma (IMCC) from hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI). METHODS: This retrospective study was institutional review board approved and the requirement for informed consent was waived. Patients who underwent gadoxetic acid-enhanced MRI with histologically confirmed IMCCs (n = 46) or HCCs (n = 58) were included. Imaging features of IMCCs and HCCs on gadoxetic acid-enhanced MRI including T2- and T1-weighted, diffusion weighted images, dynamic study and hepatobiliary phase (HBP) images were analyzed. Univariate and multivariate logistic regression analyses were performed to identify relevant differentiating features between IMCCs and HCCs. RESULTS: Multivariate analysis revealed heterogeneous T2 signal intensity and a hypointense rim on the HBP as suggestive findings of IMCCs and the wash-in and "portal wash-out" enhancement pattern as well as focal T1 high signal intensity foci as indicative of HCCs (all, p < 0.05). When we combined any three of the above four imaging features, we were able to diagnose IMCCs with 94 % (43/46) sensitivity and 86 % (50/58) specificity. CONCLUSIONS: Combined interpretation of enhancement characteristics including HBP images, morphologic features, and strict application of the "portal wash-out" pattern helped more accurate discrimination of IMCCs from HCCs. KEY POINTS: • Analysis of enhancement characteristics helped accurate discrimination of IMCCs from HCCs. • Wash-out should be determined on the PVP of gadoxetic acid-enhanced MRI. • A hypointense rim on the HBP was a significant finding of IMCCs.

Portomesenteric vein thrombosis after gastric surgery.

BACKGROUND: Postoperative portomesenteric venous thrombosis (PMVT) is a rare but potentially serious complication of gastric surgery. This study analyzed the incidence, characteristics, risk factors, and outcomes of PMVT following gastric surgery. METHODS: Medical records of patients who underwent gastric surgery between January 2007 and December 2012 were reviewed retrospectively. The risk factors of PMVT were analyzed by a logistic regression analysis with control group matched 1:4 by age, sex, and cancer stage and by a Poisson regression analysis with unmatched control group. The resolution rate of PMVT in 12 months was compared between the treatment group and the nontreatment group. RESULTS: The total incidence of PMVT after gastric surgery was 0.67 % (31/4611). Most (54.84 %) PMVT cases were detected within 1 month postoperatively. No accompanying deep vein thrombosis (DVT) was noted. Multivariate comparison with 1:4 matched control showed that combined splenectomy, synchronous malignancy, and intra-abdominal complication were independent risk factors. Advanced stage, combined splenectomy, and synchronous malignancy were independent risk factors in Poisson regression analysis using unmatched controls. The resolution rate of PMVT was not different from patients treated with anticoagulation (n = 6) or antiplatelet therapy (n = 1) and were not significantly different with those of the untreated group [85.7 % (6/7) vs. 82.3 % (14/17), p = 0.935] during 1-year follow up. CONCLUSIONS: PMVT after gastric surgery was associated with advanced cancer stage, combined splenectomy, and synchronous malignancy, but it was not related to laparoscopy or DVT. Significant differences in the natural course of PMVT were not found between the treatment group and observation group.

Efficacy of Gastric Balloon Dilatation and/or Retrievable Stent Insertion for Pyloric Spasms after Pylorus-Preserving Gastrectomy: Retrospective Analysis.

PURPOSE: We retrospectively investigated the feasibility and clinical efficacy of balloon dilatation and subsequent retrievable stent insertion, when necessitated, for pyloric spasms after pylorus-preserving gastrectomy (PPG). MATERIALS AND METHODS: Forty-five patients experiencing pyloric spasms after PPG underwent fluoroscopic balloon dilations to alleviate obstructive symptoms due to delayed gastric emptying. Patients showing poor response to balloon dilation underwent subsequent retrievable stent insertion. Safety of the procedures was analyzed, and subjective symptoms and objective signs of pyloric spasms were analyzed and compared before and after treatment. RESULTS: Thirty-three patients (73.3%, 33/45) showed good response to balloon dilatation requiring no further treatment (balloon group). Conversely, 12 patients (26.7%, 12/45) showed poor or no response after balloon dilation requiring subsequent stent insertion (stent group). Balloon dilations and/or stent insertions were safely performed in all patients except one patient who suffered a transmural tear after balloon dilatation. In both groups, mean subjective symptom score was significantly improved and mean pyloric canal-to-height of the adjacent vertebral body ratio was significantly increased after the procedures (P < .05). CONCLUSION: Balloon dilation is a safe and effective treatment for patients with pyloric spasms after PPG. In patients refractory to balloon dilations, retrievable stent placement can be a safe alternative tool.

CT differentiation of poorly-differentiated gastric neuroendocrine tumours from well-differentiated neuroendocrine tumours and gastric adenocarcinomas.

PURPOSE: To evaluate the differential CT features of gastric poorly-differentiated neuroendocrine tumours (PD-NETs) from well-differentiated NETs (WD-NETs) and gastric adenocarcinomas (ADCs) and to suggest differential features of hepatic metastases from gastric NETs and ADCs. MATERIALS AND METHODS: Our study population was comprised of 36 patients with gastric NETs (18 WD-NETs, 18 PD-NETs) and 38 patients with gastric ADCs who served as our control group. Multiple CT features were assessed to identify significant differential CT findings of PD-NETs from WD-NETs and ADCs. In addition, CT features of hepatic metastases including the metastasis-to-liver ratio were analyzed to differentiate metastatic NETs from ADCs. RESULTS: The presence of metastatic lymph nodes was the sole differentiator of PD-NETs from WD-NETs (P = .001, odds ratio = 56.67), while the presence of intact overlying mucosa with mucosal tenting was the sole significant CT feature differentiating PD-NETs from ADCs (P = .047, odds ratio = 15.3) For hepatic metastases, metastases from NETs were more hyper-attenuated than those from ADCs. CONCLUSION: The presence of metastatic LNs and intact overlying mucosa with mucosal tenting are useful CT discriminators of PD-NETs from WD-NETs and ADCs, respectively. In addition, a higher metastasis-to-liver ratio may help differentiate hepatic metastases of gastric NETs from those of gastric ADCs with high accuracy. KEY POINTS: • Presence of metastatic LNs is a useful differentiator of PD-NETs from WD-NETs. • Intact overlying mucosa with mucosal tenting suggests PD-NETs more than gastric ADCs. • Metastatic LNs are larger in size and greater in necrotic volume in PD-NETs. • Hepatic metastases from gastric NETs are more hyper-attenuated than those from ADCs.

CT findings suggesting anastomotic leak and predicting the recovery period following gastric surgery.

OBJECTIVE: To assess diagnostic performance of routine CT for detecting anastomotic leak after gastric surgery, and analyse the relationship between recovery period and CT findings. METHODS: We included 179 patients who underwent immediate CT and fluoroscopy after gastric surgery. Two reviewers retrospectively rated the possibility of leak on CT using a five-point scale focused on predefined CT findings. They also evaluated CT findings. Patients were categorised as: Group I, leak on fluoroscopy; Group II, possible leak on CT but negative on fluoroscopy; Group III, no leak. We analysed the relationship between recovery period and group. RESULTS: Area under the curve for detecting leak on CT was 0.886 in R1 and 0.668 in R2 with moderate agreement (к = 0.482). Statistically common CT findings for leak included discontinuity, large amount of air-fluid and wall thickening at anastomosis site (p < 0.05). Discontinuity at anastomosis site and a large air-fluid collection were independently associated with leak (p < 0.05). The recovery period including hospitalisation and postoperative fasting period was longer in Group I than Group II or III (p < 0.05). Group II showed a longer recovery period than Group III (p < 0.05). CONCLUSIONS: Postoperative routine CT was useful for predicting anastomotic leak using specific findings, and for predicting length of recovery period. KEY POINTS: • Anastomotic leakage remains a significant clinical problem following gastric surgery. • Routine CT without oral contrast is useful for predicting anastomotic leaking. • Wall discontinuity at anastomosis sites was an independent predictor for leaking. • CT is also useful for predicting recovery period following gastric surgery.

Effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low dose CT colonography.

PURPOSE: To assess the effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low-dose CT colonography (ULD CTC). MATERIALS AND METHODS: IRB approval and informed consents were obtained. Thirty prospectively enrolled patients underwent non-contrast CTC at 120 kVp/10 mAs in supine and 100 kVp/10 mAs in prone positions, followed by same-day colonoscopy. Images were reconstructed with filtered back projection (FBP), 80% adaptive statistical iterative reconstruction (ASIR80), and model-based iterative reconstruction (MBIR). A commercial CAD system was applied and per-polyp sensitivities and numbers of false-positives (FPs) were compared among algorithms. RESULTS: Mean effective radiation dose of CTC was 1.02 mSv. Of 101 polyps detected and removed by colonoscopy, 61 polyps were detected on supine and on prone CTC datasets on consensus unblinded review, resulting in 122 visible polyps (32 polyps<6 mm, 52 6-9.9 mm, and 38≥10 mm). Per-polyp sensitivity of CAD for all polyps was highest with MBIR (56/122, 45.9%), followed by ASIR80 (54/122, 44.3%) and FBP (43/122, 35.2%), with significant differences between FBP and IR algorithms (P<0.017). Per-polyp sensitivity for polyps≥10 mm was also higher with MBIR (25/38, 65.8%) and ASIR80 (24/38, 63.2%) than with FBP (20/38, 58.8%), albeit without statistical significance (P>0.017). Mean number of FPs was significantly different among algorithms (FBP, 1.4; ASIR, 2.1; MBIR, 2.4) (P=0.011). CONCLUSION: Although the performance of stand-alone CAD for ULD CTC can be improved, IR algorithms, particularly MBIR, were shown to significantly increase the per-polyp sensitivity of CAD compared to FBP according to this study. Therefore, as ULD CTC only requires 1.02mSv, specific optimization of CAD for ULD CTC and IR algorithms is strongly warranted to make ULD CTC with CAD clinically viable.

Usefulness of a metal artifact reduction algorithm for orthopedic implants in abdominal CT: phantom and clinical study results.

OBJECTIVE. The purpose of this study was to evaluate the usefulness of a metal artifact reduction (MAR) algorithm for orthopedic prostheses in phantom and clinical CT. MATERIALS AND METHODS. An agar phantom with two sets of spinal screws was scanned at various tube voltage (80-140 kVp) and tube current-time (34-1032 mAs) settings. The orthopedic MAR algorithm was combined with filtered back projection (FBP) or iterative reconstruction. The mean SDs in three ROIs were compared among four datasets (FBP, iterative reconstruction, FBP with orthopedic MAR, and iterative reconstruction with orthopedic MAR). For the clinical study, the mean SDs of three ROIs and 4-point scaled image quality in 52 patients with metallic orthopedic prostheses were compared between CT images acquired with and without orthopedic MAR. The presence and type of image quality improvement with orthopedic MAR and the presence of orthopedic MAR-related new artifacts were also analyzed. RESULTS. In the phantom study, the mean SD with orthopedic MAR was significantly lower than that without orthopedic MAR regardless of dose settings and reconstruction algorithms (FBP versus iterative reconstruction). The mean SD near the metallic prosthesis in 52 patients was significantly lower on CT images with orthopedic MAR (28.04 HU) than those without it (49.21 HU). Image quality regarding metallic artifact was significantly improved with orthopedic MAR (rating of 2.60 versus 1.04). Notable reduction of metallic artifacts and better depiction of abdominal organs were observed in 45 patients. Diagnostic benefit was achieved in six patients, but orthopedic MAR-related new artifacts were seen in 30 patients. CONCLUSION. Use of the orthopedic MAR algorithm significantly reduces metal artifacts in CT of both phantoms and patients and has potential for improving diagnostic performance in patients with severe metallic artifacts.