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.

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 ㎣ ; 95% confidence interval [CI], 4.9–24.3 ㎣ ); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, -0.7 ㎣ ; 95% CI, -9.1–7.7 ㎣ ). 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 ㎟ ; 95% CI, 0.89–1.25 ㎟ ) but not in the larger lumen area group (mean of difference, -0.07 ㎟ ; 95% CI, -0.22–0.08 ㎟ ). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 ㎟ ; 95% CI, 0.27–0.65 ㎟ ) than in that of IVUS and SATM (1.53 ㎟ ; 95% CI, 1.27–1.79㎟ ). @*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

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 nonacute 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.

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 ㎣ ; 95% confidence interval [CI], 4.9–24.3 ㎣ ); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, -0.7 ㎣ ; 95% CI, -9.1–7.7 ㎣ ). 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 ㎟ ; 95% CI, 0.89–1.25 ㎟ ) but not in the larger lumen area group (mean of difference, -0.07 ㎟ ; 95% CI, -0.22–0.08 ㎟ ). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 ㎟ ; 95% CI, 0.27–0.65 ㎟ ) than in that of IVUS and SATM (1.53 ㎟ ; 95% CI, 1.27–1.79㎟ ). @*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

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 nonacute 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.

Erratum: Correction of Notes. In vitro MRI and Characterization of Rat Mesenchymal Stem Cells Transduced with Ferritin as MR Reporter Gene

We found an error in our published article.

Noninvasive Assessment of Hepatic Fibrosis in Patients with Chronic Hepatitis B Viral Infection Using Magnetic Resonance Elastography

OBJECTIVE: To evaluate the diagnostic performance of magnetic resonance elastography (MRE) for staging hepatic fibrosis in patients with chronic hepatitis B virus (HBV) infection. MATERIALS AND METHODS: Patients with chronic HBV infection who were suspected of having focal or diffuse liver diseases (n = 195) and living donor candidates (n = 166) underwent MRE as part of the routine liver MRI examination. We measured liver stiffness (LS) values on quantitative shear stiffness maps. The technical success rate of MRE was then determined. Liver cell necroinflammatory activity and fibrosis were assessed using histopathologic examinations as the reference. Areas under the receiver operating characteristic curve (Az) were calculated in order to predict the liver fibrosis stage. RESULTS: The technical success rate of MRE was 92.5% (334/361). The causes of technical failure were poor wave propagation (n = 12), severe respiratory motion (n = 3), or the presence of iron deposits in the liver (n = 12). The mean LS values, as measured by MRE, increased significantly along with an increase in the fibrosis stage (r = 0.901, p or = F1, > or = F2, > or = F3, and F4 were 2.45 kPa, 2.69 kPa, 3.0 kPa, and 3.94 kPa, respectively, and with Az values of 0.987-0.988. CONCLUSION: MRE has a high technical success rate and excellent diagnostic accuracy for staging hepatic fibrosis in patients with chronic HBV infection.

CT Findings of Gallbladder Metastases: Emphasis on Differences According to Primary Tumors

OBJECTIVE: To describe computed tomography (CT) features of metastatic gallbladder (GB) tumors (MGTs) from various primary tumors and to determine whether there are differential imaging features of MGTs according to different primary tumors. MATERIALS AND METHODS: Twenty-one patients who had pathologically confirmed MGTs and underwent CT were retrospectively enrolled. Clinical findings including presenting symptoms, type of surgery, and interval between primary and metastatic tumors were recorded. Histologic features of primary tumor and MGTs including depth of invasion were also reviewed. Imaging findings were analyzed for the location and morphology of MGTs, pattern and degree of enhancement, depth of invasion, presence of intact overlying mucosa, and concordance between imaging features of primary and metastatic tumors. Significant differences between the histologies of MGTs and imaging features were determined. RESULTS: The most common primary tumor metastasized to the GB was gastric cancer (n = 8), followed by renal cell carcinoma (n = 4) and hepatocellular carcinoma (n = 3). All MGTs (n = 21) manifested as infiltrative wall thickenings (n = 15) or as polypoid lesions (n = 6) on CT, similar to the features of primary GB cancers. There were significant differences in the morphology of MGTs, enhancement pattern, enhancement degree, and depth of invasion according to the histology of primary tumors (p < 0.05). Metastatic adenocarcinomas of the GB manifested as infiltrative and persistently enhancing wall thickenings, while non-adenocarcinomatous metastases usually manifested as polypoid lesions with early wash-in and wash-out. CONCLUSION: Although CT findings of MGTs are similar to those of primary GB cancer, they are significantly different between the various histologies of primary tumors.

Rat Model of Hindlimb Ischemia Induced via Embolization with Polyvinyl Alcohol and N-Butyl Cyanoacrylate

OBJECTIVE: To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). MATERIALS AND METHODS: Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. RESULTS: There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). CONCLUSION: The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model.

In vitro MRI and Characterization of Rat Mesenchymal Stem Cells Transduced with Ferritin as MR Reporter Gene

PURPOSE: This study was performed to evaluate the characteristics of rat mesenchymal stem cells (RMSCs) transduced with human ferritin gene and investigate in vitro MRI detectability of ferritin-transduced RMSCs. MATERIALS AND METHODS: The RMSCs expressing both myc-tagged human ferritin heavy chain subunit (myc-FTH) and green fluorescence protein (GFP) were transduced with lentiviurs. Transduced cells were sorted by GFP expression using a fluorescence-activated cell sorter. Myc-FTH and GFP expression in transduced cells were detected by immunofluorescence staining. The cell proliferative ability and viability were assessed by MTT assay. The RMSC surface markers (CD29+/CD45-) were analyzed by flow cytometry. The intracellular iron amount was measured spectrophotometically and the presence of ferritin-iron accumulation was detected by Prussian blue staining. In vitro magnetic resonance imaging (MRI) study of cell phantoms was done on 9.4 T MR scanner to evaluate the feasibility of imaging the ferritin-transduced RMSCs. RESULTS: The myc-FTH and GFP genes were stably transduced into RMSCs. No significant differences were observed in terms of biologic properties in transduced RMSCs compared with non-transduced RMSCs. Ferritin-transduced RMSCs exhibited increased iron accumulation ability and showed significantly lower T2 relaxation time than non-transduced RMSCs. CONCLUSION: Ferritin gene as MR reporter gene could be used for non-invasive tracking and visualization of therapeutic mesenchymal stem cells by MRI.

Clinical Application of Liver MR Imaging in Wilson's Disease

OBJECTIVE: To determine whether there is a correlation between liver MR findings and the clinical manifestations and severity of liver dysfunction in patients with Wilson's disease. MATERIALS AND METHODS: Two radiologists retrospectively evaluated MR images of the liver in 50 patients with Wilson's disease. The Institutional Review Board approved this retrospective study and informed consent was waived. MR images were evaluated with a focus on hepatic contour abnormalities and the presence of intrahepatic nodules. By using Fisher's exact test, MR findings were compared with clinical presentations (neurological and non-neurological) and hepatic dysfunction, which was categorized by the Child-Pugh classification system (A, B and C). Follow-up MR images were available for 17 patients. RESULTS: Contour abnormalities of the liver and intrahepatic nodules were observed in 31 patients (62%) and 25 patients (50%), respectively. Each MR finding showed a statistically significant difference (p < 0.05) among the three groups of Child-Pugh classifications (A, n = 36; B, n = 5; C, n = 9), except for splenomegaly (p = 0.243). The mean age of the patients with positive MR findings was higher than that of patients with negative MR findings. For patients with Child-Pugh class A (n = 36) with neurological presentation, intrahepatic nodules, surface nodularity, and gallbladder fossa widening were more common. Intrahepatic nodules were improved (n = 8, 47%), stationary (n = 5, 29%), or aggravated (n = 4, 24%) on follow-up MR images. CONCLUSION: MR imaging demonstrates the contour abnormalities and parenchymal nodules of the liver in more than half of the patients with Wilson's disease, which correlates with the severity of hepatic dysfunction and clinical manifestations.

Treatment Strategy of Transcatheter Arterial Embolization after Pelvic CT Angiography in Traumatic Pelvic Hemorrhage: A Single Regional Emergency Center's Experience

PURPOSE: This study was conducted to evaluate the effectiveness of the treatment strategy of transcatheter arterial embolization after pelvic CT angiography (CTA) in cases of traumatic pelvic hemorrhage. METHODS: This is a retrospective analysis of pelvic hemorrhage patients who underwent transcatheter arterial embolization after pelvic CTA at our regional emergency center during a 31-month period. We reviewed the medical records and imagings of all these patients. RESULTS: Transcatheter arterial embolization was performed in 17 patients (M:F=7:10, mean age=53.9) who underwent pelvic CTA for the evaluation of traumatic pelvic hemorrhage. Arterial bleeding was demonstrated on pelvic CTA in all patients, and the combined injury was also noted in 13 patients. The admission-to-CTA time was 84.53+/-66.92 minutes, and the CTA-to-embolization time was 147.65+/-99.97 minutes. Extravasation of contrast media or pseudoaneurysm was demonstrated on conventional angiography in all patients. Unilateral iliac artery embolization was performed in 8 patients, and bilateral iliac artery embolization was performed in 9 patients. Additional embolizations other than in the iliac arteries were performed in 7 patients. Initial hemostasis was achieved in 16 patients. One patient died of ongoing pelvic bleeding. Rebleeding occurred in only one patient and hemostasis was achieved with the second embolization. Another patient died of intracranial and facial bleeding in spite of pelvic hemostasis. The overall mortality was 11.8%, and there was no significant adverse effects in the other patients. CONCLUSION: Transcatheter arterial embolization after pelvic CTA is an effective treatment strategy in the management of traumatic pelvic hemorrhage patients.

Overnight Preliminary Interpretations of CT and MR Images by Radiology Residents in ER: How Accurate Are They?

PURPOSE: At many institutes in Korea, preliminary interpretations of after-hours CT and MR images are performed by radiology residents, with the attending radiologist's reviewing the interpretations the next day. The purpose of this study was to assess the rate of discrepancy between residents' interpretations and the final interpretations performed by attending radiologists. METHODS: We reviewed the interpretations of 1381 CT and 404 MRI scans that were obtained at the emergency department of our institute over three months. Any discrepancies between the preliminary and final interpretations were categorized as either major or minor discrepancies with a major discrepancy defined as one resulting in a change in diagnosis and treatment plans. We conducted patient follow-up via a retrospective review of the medical records to evaluate the clinical outcomes of the discrepancies. RESULTS: The rate of major discrepancies was 2.5%, and the rate of minor discrepancies was 11.4%. Major discrepancies led to a change in diagnosis or patient treatment plans, but did not lead to any increase in patient morbidity. CONCLUSION: The discrepancy rate at our institution was relatively insignificant, and patient care at the emergency department was not adversely affected by having radiology residents interpret CT and MRI scans after-hours and the attending radiologist review the interpretations the next morning. Still, further efforts are needed in order to reduce the frequency of major discrepancies.

New Around-the-clock Radiology Coverage System for the Emergency Department: A Satisfaction Survey among Clinicians

PURPOSE: The purpose of this study was to assess the clinician satisfaction of a newly introduced around-the-clock radiology coverage system for the emergency department. MATERIALS AND METHODS: Seventeen emergency physicians (8 board certified physicians, 9 residents) were invited to fill out a survey pertaining to the newly introduced radiology coverage system for the emergency department. The questionnaire included 10 questions covering three major topics. The first topic related to the around-the-clock radiology coverage by two full-time radiology residents. The second topic focused on the preliminary interpretations of radiology residents. The last topic included the interpretation assistance system by board-certified radiologists. The answers to each question were assessed using a scoring system of 1 to 5. RESULTS: The mean satisfaction score of the around-the-clock radiology coverage system by the two full-time radiology residents was 4.6 (range 3-5). The mean score for the preliminary interpretation system by the radiology residents was 4.8 (range 4-5). The score for the reliability of the preliminary versus the final interpretations was 4.1 (range 4-5). Lastly, the mean score for the interpretation assistance system by board-certified radiologists was 4.9 (range 4-5). CONCLUSION: The results of this study indicate a high satisfaction rating among clinicians' of the new around-the-clock radiology coverage system for the emergency department.

Endovascular Therapy of Left Subclavian Artery Stenosis in Patients with Left Internal Mammary-Coronary Artery Bypass Graft

PURPOSE: We wanted to evaluate the clinical usefulness of percutaneous transluminal angioplasty (PTA) and stenting of left subclavian artery (LSA) stenosis in the patients with a left internal mammary artery (LIMA)-coronary artery bypass graft. MATERIALS AND METHODS: From September 1998 to November 2005, significant proximal LSA stenoses were treated with PTA and stenting in 22 patients (15 men and 7 women) who had a prior LIMA-coronary artery bypass graft or who were willing to undergo LIMA-coronary artery bypass grafting. The technical success rates, complications and restenosis during the follow-up period were retrospectively evaluated. RESULTS: Six patients had a prior LIMA bypass graft and 16 patients were treated before their coronary artery bypass surgery. The etiology of the LSA stenosis was atherosclerosis in all patients. Four patients were treated with PTA only, and stents were placed in 18 patients. Technical success was achieved in all patients. An embolism in the proximal LIMA occurred after stenting in one patient, and the LIMA was recanalized with transcatheter thrombolysis. During a mean follow-up of 30 months, only one patient was found to have recurrent LSA stenosis 29 months after stenting and this patient was successfully managed with angioplasty. CONCLUSION: Endovascular therapy is useful and efficacious for the treatment of LSA stenosis in patients with a LIMA-coronary artery bypass graft.