Combined intravitreal methotrexate and immunochemotherapy followed by reduced-dose whole-brain radiotherapy for newly diagnosed B-cell primary intraocular lymphoma.

Primary intraocular lymphoma (IOL) has a propensity for central nervous system (CNS) relapse within 2 years of initial diagnosis, affecting clinical outcome. To reduce CNS relapse, we performed the combination treatment protocols of intravitreal methotrexate injections, methotrexate-based systemic induction chemotherapy and consolidation high-dose cytarabine and reduced-dose whole brain radiation therapy (rdWBRT, 23·4 Gy) for B-cell primary IOL with or without newly diagnosed CNS involvement. All patients underwent longitudinal brain magnetic resonance imaging (MRI) and cognitive assessment for evaluation of treatment-induced leucoencephalopathy. Seventeen patients initiated and 16 completed the protocol treatment. CNS relapse occurred in 2 patients and intraocular relapse in 3. Four-year progression-free survival (PFS) was 74·9% and 4-year overall survival (OS) was 86·3%, with a median follow-up period of 48·9 months. Of 11 patients without CNS involvement, 1 had CNS relapse and 3 intraocular relapse, and 4-year PFS and OS was 72·7% and 88·9%, respectively. Although white matter abnormalities shown by MRI were significantly increased at 4 years after rdWBRT, only one patient developed mild cognitive impairment. The combination of intravitreal chemotherapy, prophylactic systemic chemotherapy and rdWBRT for primary IOL showed a potential to reduce CNS relapse rate and improved 4-year PFS and OS without increase of cognitive dysfunction.

The effect of expert knowledge on medical search: medical experts have specialized abilities for detecting serious lesions.

How does domain-specific knowledge influence the experts' performance in their domain of expertise? Specifically, can visual search experts find, with uniform efficiency, any type of target in their domain of expertise? We examined whether acquired knowledge of target importance influences an expert's visual search performance. In some professional searches (e.g., medical screenings), certain targets are rare; one aim of this study was to examine the extent to which experts miss such targets in their searches. In one experiment, radiologists (medical experts) engaged in a medical lesion search task in which both the importance (i.e., seriousness/gravity) and the prevalence of targets varied. Results showed decreased target detection rates in the low prevalence conditions (i.e., the prevalence effect). Also, experts were better at detecting important (versus unimportant) lesions. Results of an experiment using novices ruled out the possibility that decreased performance with unimportant targets was due to low target noticeability/visibility. Overall, the findings suggest that radiologists do not have a generalized ability to detect any type of lesion; instead, they have acquired a specialized ability to detect only those important lesions relevant for effective medical practices.

Gallbladder hemorrhage associated with segmental arterial mediolysis: a case report.

BACKGROUND: Gallbladder hemorrhage is a rare but fatal condition. The reported causes of gallbladder hemorrhage include iatrogenesis, atherosclerotic changes in the cystic arteries, acute cholecystitis or cholelithiasis, malignancy, trauma, hemophilia, pseudoaneurysm, and the use of oral anticoagulant medications. Recently, segmental arterial mediolysis (SAM) has been reported as a possible etiology of life-threatening abdominal, retroperitoneal, and intracranial hemorrhages. However, no previous reports have described the association between gallbladder hemorrhage and SAM. CASE PRESENTATION: A 59-year-old man was transferred to our hospital complaining of upper abdominal pain and vomiting. Contrast-enhanced computed tomography revealed high-density images of the gallbladder and common bile duct. However, there were no obvious findings of gallstones, cholecystitis, tumors, or aneurysms. He was diagnosed with gallbladder hemorrhage and bile duct obstruction. We performed a laparoscopic cholecystectomy after endoscopic biliary drainage. The gross appearance of the surgically resected specimen showed 12 small (3-12 mm), slightly elevated lesions on the gallbladder mucosa. Histologically, these slightly elevated lesions consisted of dilated muscular arteries of the gallbladder wall with fibrinoid degeneration of the media and focal loss of the internal and external elastic laminae. The histopathological diagnosis was confirmed as SAM. CONCLUSIONS: To the best of our knowledge, this is the first reported case of a gallbladder hemorrhage associated with SAM. Our case report shows that SAM can cause gallbladder hemorrhage, suggesting that SAM should be considered in the differential diagnosis of gallbladder hemorrhage.

Peritoneal fluid accumulation in healthy men and postmenopausal women: evaluation on pelvic MRI.

OBJECTIVE: The purpose of this article is to investigate the prevalence, volume, and location of peritoneal fluid accumulation and to clarify the clinical significance of a small amount of peritoneal fluid accumulation in healthy men and postmenopausal women on pelvic MRI. MATERIALS AND METHODS: Pelvic MRI was performed on 1017 healthy men and 310 healthy postmenopausal women. Two radiologists independently interpreted images and judged the presence or absence of fluid in the peritoneal cavity. For cases in which peritoneal fluid was detected, the volume and the location were recorded. RESULTS: Peritoneal fluid was identified in 39 of 1017 (3.8%) healthy men and 52 of 310 (16.8%) healthy postmenopausal women. Healthy postmenopausal women had a much higher prevalence than did healthy men (p < 0.0001). The mean (± SD) total volume of fluid accumulation was 3.0 ± 2.7 mL in healthy men and 2.3 ± 2.0 mL in postmenopausal women. The volume of total peritoneal fluid was less than 10 mL in all but one man, who had 10.3 mL of peritoneal fluid accumulation. Peritoneal fluid accumulation was located below the level of the S3 vertebra in all subjects. CONCLUSION: A small amount of peritoneal fluid accumulation is occasionally observed in healthy men and postmenopausal women on pelvic MRI. Pelvic peritoneal fluid accumulation of less than 10 mL is not considered to be of clinical significance in men and postmenopausal women.

Model-based iterative reconstruction technique for radiation dose reduction in chest CT: comparison with the adaptive statistical iterative reconstruction technique.

OBJECTIVES: To prospectively evaluate dose reduction and image quality characteristics of chest CT reconstructed with model-based iterative reconstruction (MBIR) compared with adaptive statistical iterative reconstruction (ASIR). METHODS: One hundred patients underwent reference-dose and low-dose unenhanced chest CT with 64-row multidetector CT. Images were reconstructed with 50 % ASIR-filtered back projection blending (ASIR50) for reference-dose CT, and with ASIR50 and MBIR for low-dose CT. Two radiologists assessed the images in a blinded manner for subjective image noise, artefacts and diagnostic acceptability. Objective image noise was measured in the lung parenchyma. Data were analysed using the sign test and pair-wise Student's t-test. RESULTS: Compared with reference-dose CT, there was a 79.0 % decrease in dose-length product with low-dose CT. Low-dose MBIR images had significantly lower objective image noise (16.93 ± 3.00) than low-dose ASIR (49.24 ± 9.11, P < 0.01) and reference-dose ASIR images (24.93 ± 4.65, P < 0.01). Low-dose MBIR images were all diagnostically acceptable. Unique features of low-dose MBIR images included motion artefacts and pixellated blotchy appearances, which did not adversely affect diagnostic acceptability. CONCLUSION: Diagnostically acceptable chest CT images acquired with nearly 80 % less radiation can be obtained using MBIR. MBIR shows greater potential than ASIR for providing diagnostically acceptable low-dose CT images without severely compromising image quality. KEY POINTS: • Model-based iterative reconstruction (MBIR) creates high-quality low-dose CT images. • MBIR significantly improves image noise and artefacts over adaptive statistical iterative techniques. • MBIR shows greater potential than ASIR for diagnostically acceptable low-dose CT. • The prolonged processing time of MBIR may currently limit its routine use in clinical practice.

Differential diagnosis and laparoscopic resection of an adrenal pseudocyst: A case report.

BACKGROUND: Adrenal pseudocysts are infrequent entities and definite preoperative diagnosis is difficult. We present a case of left adrenal pseudocyst, which was intraoperatively identified as having an adrenal origin and was resected using a laparoscopic approach. PRESENTATION OF CASE: A 41-year-old female was referred to our hospital for examination and treatment of a cystic lesion in the pancreatic tail. Preoperative diagnostic imaging studies showed a cystic lesion with intramural nodular structure, measuring 39 mm in the largest diameter and located between the pancreatic tail and the left adrenal gland. However, the origin of the cystic lesion remained unclear, and a definite preoperative diagnosis was not established. The cystic lesion was intraoperatively identified as having an adrenal origin after the division of the loose connective tissue layer around the lesion under the laparoscopic magnified view. Laparoscopic left adrenalectomy was performed as radical treatment and the histopathological diagnosis confirmed the presence of an adrenal pseudocyst. DISCUSSION: We could not ascertain the origin of the cystic lesion from the left adrenal gland and establish a definite diagnosis based on the findings of the preoperative diagnostic imaging modalities. Laparoscopic surgery could be more advantageous than the conventional open approach as not only a minimally invasive treatment option but also as an intraoperative diagnostic tool for cystic lesions in the pancreatic tail. CONCLUSION: This case report suggests that laparoscopic surgery could be clinically useful as not only a minimally invasive treatment but also an intraoperative diagnostic tool for cystic lesions in the pancreatic tail region.

Massive splenic infarction and splenic venous thrombosis observed in a patient with acute splenic syndrome of sickle cell traits on contrast-enhanced thin-slice computed tomography.

We report a case of splenic infarction in a patient with sickle cell traits (SCT), focusing on the computed tomography (CT) findings. The patient was an African-American man in his twenties with no past medical history who experienced sudden left upper quadrant pain while climbing a mountain (over 3000 m above sea level). Dynamic contrast-enhanced CT revealed massive non-segmental splenic infarction accompanied with nodule-like preserved splenic tissue. The region of splenic infarction did not coincide with the arterial vascular territory and differed from the features of infarction caused by large arterial embolism. In addition, thrombotic occlusion of the distal splenic vein was depicted on plain and contrast-enhanced thin-slice CT images. Early-phase contrast-enhanced images also showed inhomogeneous enhancement of the hepatic parenchyma. The patient's symptoms improved with conservative therapy. A hemoglobin electrophoresis test confirmed the diagnosis of SCT. SCT is usually asymptomatic, but hypoxic environments may induce acute splenic syndrome, which is commonly manifested as splenic infarction. We observed splenic venous thrombosis and inhomogeneous hepatic parenchymal enhancement in addition to a huge splenic infarction in our patient. To the best of our knowledge, this is the first report describing the specific imaging findings, particularly splenic venous thrombosis and inhomogeneous hepatic parenchymal enhancement, of acute splenic syndrome in a patient with previously undiagnosed SCT. These findings demonstrate the pathophysiology of SCT, and may help with the diagnosis of this disease.

Comparison of new and conventional versions of model-based iterative reconstruction in reduced-dose computed tomography for diagnosis of hepatic steatosis.

PURPOSE: To compare new and conventional versions of model-based iterative reconstruction (MBIR) in reduced-dose computed tomography (CT) in terms of diagnostic performance for hepatic steatosis. MATERIALS AND METHODS: Images were reconstructed from standard-dose and aggressively reduced-dose (the dose-length product was reduced by 91 %) unenhanced abdominopelvic CT scans of 86 patients using filtered back projection (SD-FBP) and new and conventional versions of MBIR (RD-MBIRn and RD-MBIRc), respectively. The mean CT attenuation of the liver (CT[L]) and the spleen as well as the ratio of these parameters (CT[L/S]) were calculated. CT[L] <48 Hounsfield units (HU) and CT[L/S] <1.1 were applied to SD-FBP (used as the reference standard; the number of positive patients was 12 and 14, respectively), RD-MBIRn, and RD-MBIRc. RESULTS: CT[L]s in SD-FBP/RD-MBIRn/RD-MBIRc were 56.9/55.9/52.8 HU. The difference in CT[L] between RD-MBIRn and SD-FBP was within ±5.0 HU in most cases. The sensitivity/specificity/accuracy of CT[L] <48 HU in RD-MBIRn and RD-MBIRc were 1.00/0.97/0.98 and 1.00/0.92/0.93, respectively, showing that RD-MBIRn permits significant improvements in specificity and accuracy (P < 0.05, McNemar test). For CT[L/S] <1.1, these values were 0.79/0.97/0.94 and 0.79/0.97/0.94 in RD-MBIRn and RD-MBIRc, respectively. CONCLUSION: When CT[L] <48 HU was applied, RD-MBIRn presented a significantly improved hepatic steatosis diagnostic performance compared with RD-MBIRc; indeed, it was almost equivalent to that afforded by SD-FBP.

Model-based iterative reconstruction and adaptive statistical iterative reconstruction: dose-reduced CT for detecting pancreatic calcification.

BACKGROUND: Iterative reconstruction methods have attracted attention for reducing radiation doses in computed tomography (CT). PURPOSE: To investigate the detectability of pancreatic calcification using dose-reduced CT reconstructed with model-based iterative construction (MBIR) and adaptive statistical iterative reconstruction (ASIR). MATERIAL AND METHODS: This prospective study approved by Institutional Review Board included 85 patients (57 men, 28 women; mean age, 69.9 years; mean body weight, 61.2 kg). Unenhanced CT was performed three times with different radiation doses (reference-dose CT [RDCT], low-dose CT [LDCT], ultralow-dose CT [ULDCT]). From RDCT, LDCT, and ULDCT, images were reconstructed with filtered-back projection (R-FBP, used for establishing reference standard), ASIR (L-ASIR), and MBIR and ASIR (UL-MBIR and UL-ASIR), respectively. A lesion (pancreatic calcification) detection test was performed by two blinded radiologists with a five-point certainty level scale. RESULTS: Dose-length products of RDCT, LDCT, and ULDCT were 410, 97, and 36 mGy-cm, respectively. Nine patients had pancreatic calcification. The sensitivity for detecting pancreatic calcification with UL-MBIR was high (0.67-0.89) compared to L-ASIR or UL-ASIR (0.11-0.44), and a significant difference was seen between UL-MBIR and UL-ASIR for one reader (P = 0.014). The area under the receiver-operating characteristic curve for UL-MBIR (0.818-0.860) was comparable to that for L-ASIR (0.696-0.844). The specificity was lower with UL-MBIR (0.79-0.92) than with L-ASIR or UL-ASIR (0.96-0.99), and a significant difference was seen for one reader (P < 0.01). CONCLUSION: In UL-MBIR, pancreatic calcification can be detected with high sensitivity, however, we should pay attention to the slightly lower specificity.

Dose-reduced CT with model-based iterative reconstruction in evaluations of hepatic steatosis: how low can we go?

PURPOSE: To determine whether dose-reduced CT with model-based iterative image reconstruction (MBIR) is a useful tool with which to diagnose hepatic steatosis. MATERIALS AND METHODS: This prospective clinical study approved by our Institutional Review Board included 103 (67 men and 36 women; mean age, 64.3 years) patients who provided written informed consent to undergo unenhanced CT. Images of reference-dose CT (RDCT) with filtered back projection (R-FBP) and low- and ultralow-dose CT (dose-length product; 24 and 9% of that of RDCT) with MBIR (L-MBIR and UL-MBIR) were reconstructed. Mean CT numbers of liver (CT[L]) and spleen (CT[S]), and quotient (CT[L/S]) of CT[L] and CT[S] were calculated from selected regions of interest. Bias and limits of agreement (LOA) of CT[L] and CT[L/S] in L-MBIR and UL-MBIR (vs. R-FBP) were assessed using Bland-Altman analyses. Diagnostic methods for hepatic steatosis of CT[L]<48 Hounsfield units (HU) and CT[L/S]<1.1 were applied to L-MBIR and UL-MBIR using R-FBP as the reference standard. RESULTS: Bias was larger for CT[L] in UL-MBIR than in L-MBIR (-3.18HU vs. -1.73HU). The LOA of CT[L/S] was larger for UL-MBIR than for L-MBIR (±0.425 vs. ±0.245) and outliers were identified in CT[L/S] of UL-MBIR. Accuracy (0.92-0.95) and the area under the receiver operating characteristics curve (0.976-0.992) were high for each method, but some were slightly lower in UL-MBIR than L-MBIR. CONCLUSION: Dose-reduced CT reconstructed with MBIR is applicable to diagnose hepatic steatosis, however, a low dose of radiation might be preferable.

Model-based iterative reconstruction for reduction of radiation dose in abdominopelvic CT: comparison to adaptive statistical iterative reconstruction.

PURPOSE: To evaluate dose reduction and image quality of abdominopelvic computed tomography (CT) reconstructed with model-based iterative reconstruction (MBIR) compared to adaptive statistical iterative reconstruction (ASIR). MATERIALS AND METHODS: In this prospective study, 85 patients underwent referential-, low-, and ultralow-dose unenhanced abdominopelvic CT. Images were reconstructed with ASIR for low-dose (L-ASIR) and ultralow-dose CT (UL-ASIR), and with MBIR for ultralow-dose CT (UL-MBIR). Image noise was measured in the abdominal aorta and iliopsoas muscle. Subjective image analyses and a lesion detection study (adrenal nodules) were conducted by two blinded radiologists. A reference standard was established by a consensus panel of two different radiologists using referential-dose CT reconstructed with filtered back projection. RESULTS: Compared to low-dose CT, there was a 63% decrease in dose-length product with ultralow-dose CT. UL-MBIR had significantly lower image noise than L-ASIR and UL-ASIR (all p<0.01). UL-MBIR was significantly better for subjective image noise and streak artifacts than L-ASIR and UL-ASIR (all p<0.01). There were no significant differences between UL-MBIR and L-ASIR in diagnostic acceptability (p>0.65), or diagnostic performance for adrenal nodules (p>0.87). CONCLUSION: MBIR significantly improves image noise and streak artifacts compared to ASIR, and can achieve radiation dose reduction without severely compromising image quality.

Model-based iterative reconstruction technique for ultralow-dose chest CT: comparison of pulmonary nodule detectability with the adaptive statistical iterative reconstruction technique.

PURPOSE: The purpose of this study was to evaluate whether model-based iterative reconstruction (MBIR) enables dose reduction over adaptive iterative reconstruction (ASIR) while maintaining diagnostic performance. METHODS: In this institutional review board-approved and Health Insurance Portability and Accountability Act-compliant study, 59 patients (mean [SD] age, 64.7 [13.4] years) gave informed consent to undergo reference-, low-, and ultralow-dose chest computed tomography (CT) with 64-row multidetector CT. The reference- and low-dose CT involved the use of automatic tube current modulation with fixed noise indices (31.5 and 70.44 at 0.625 mm, respectively) and were reconstructed with 50% ASIR-filtered back projection blending. The ultralow-dose CT was acquired with a fixed tube current-time product of 5 mA s and reconstructed with MBIR. Two radiologists evaluated 2.5- and 0.625-mm-slice-thick axial images from low-dose ASIR and ultralow-dose MBIR, recorded the pattern of each nodule candidate, and assigned each a confidence score. A reference standard was established by a consensus panel of 2 different radiologists, who identified 84 noncalcified nodules with diameters of 4 mm or greater on reference-dose ASIR (ground-glass opacity, n = 18; partly solid, n = 11; solid, n = 55). Sensitivity in nodule detection was assessed using the McNemar test. Jackknife alternative free-response receiver operating characteristic (JAFROC) analysis was applied to assess the results including confidence scores. RESULTS: Compared with the low-dose CT, a 78.1% decrease in dose-length product was seen with the ultralow-dose CT. No significant differences were observed between the low-dose ASIR and the ultralow-dose MBIR for overall nodule detection in sensitivity (P = 0.48-0.69) or the JAFROC analysis (P = 0.57). Likewise, no significant differences were seen for ground-glass opacity, partly solid, or solid nodule detection in sensitivity (P = 0.08-0.65) or the JAFROC analysis (P = 0.21-0.90). CONCLUSIONS: Model-based iterative reconstruction enables nearly an 80% reduction in radiation dose for chest CT from a low-dose level to an ultralow-dose level, without affecting nodule detectability.

Comparison of pure and hybrid iterative reconstruction techniques with conventional filtered back projection: image quality assessment in the cervicothoracic region.

OBJECTIVES: To evaluate the impact on image quality of three different image reconstruction techniques in the cervicothoracic region: model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP). METHODS: Forty-four patients underwent unenhanced standard-of-care clinical computed tomography (CT) examinations which included the cervicothoracic region with a 64-row multidetector CT scanner. Images were reconstructed with FBP, 50% ASIR-FBP blending (ASIR50), and MBIR. Two radiologists assessed the cervicothoracic region in a blinded manner for streak artifacts, pixilated blotchy appearances, critical reproduction of visually sharp anatomical structures (thyroid gland, common carotid artery, and esophagus), and overall diagnostic acceptability. Objective image noise was measured in the internal jugular vein. Data were analyzed using the sign test and pair-wise Student's t-test. RESULTS: MBIR images had significant lower quantitative image noise (8.88 ± 1.32) compared to ASIR images (18.63 ± 4.19, P<0.01) and FBP images (26.52 ± 5.8, P<0.01). Significant improvements in streak artifacts of the cervicothoracic region were observed with the use of MBIR (P<0.001 each for MBIR vs. the other two image data sets for both readers), while no significant difference was observed between ASIR and FBP (P>0.9 for ASIR vs. FBP for both readers). MBIR images were all diagnostically acceptable. Unique features of MBIR images included pixilated blotchy appearances, which did not adversely affect diagnostic acceptability. CONCLUSIONS: MBIR significantly improves image noise and streak artifacts of the cervicothoracic region over ASIR and FBP. MBIR is expected to enhance the value of CT examinations for areas where image noise and streak artifacts are problematic.

Effect of radiation dose and adaptive statistical iterative reconstruction on image quality of pulmonary computed tomography.

PURPOSE: The purpose of this study was to assess the effects of dose and adaptive statistical iterative reconstruction (ASIR) on image quality of pulmonary computed tomography (CT). MATERIALS AND METHODS: Inflated and fixed porcine lungs were scanned with a 64-slice CT system at 10, 20, 40 and 400 mAs. Using automatic exposure control, 40 mAs was chosen as standard dose. Scan data were reconstructed with filtered back projection (FBP) and ASIR. Image pairs were obtained by factorial combination of images at a selected level. Using a 21-point scale, three experienced radiologists independently rated differences in quality between adjacently displayed paired images for image noise, image sharpness and conspicuity of tiny nodules. A subjective quality score (SQS) for each image was computed based on Anderson's functional measurement theory. The standard deviation was recorded as a quantitative noise measurement. RESULTS: At all doses examined, SQSs improved with ASIR for all evaluation items. No significant differences were noted between the SQSs for 40%-ASIR images obtained at 20 mAs and those for FBP images at 40 mAs. CONCLUSION: Compared to the FBP algorithm, ASIR for lung CT can enable an approximately 50% dose reduction from the standard dose while preserving visualization of small structures.

Fate of hypointense lesions on Gd-EOB-DTPA-enhanced magnetic resonance imaging.

PURPOSE: To investigate the natural outcome and clinical implication of hypointense lesions in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI. MATERIALS AND METHODS: Forty patients underwent Gd-EOB-DTPA-enhanced MRI for preoperative evaluation of HCC. Hypointense lesions in the hepatobiliary phase that were hypovascular 5mm of more were extracted for follow-up. We performed a longitudinal study retrospectively for these lesions regardless of whether classical HCC developed or emerged in a different area from that of the lesions being followed. RESULTS: Thirty one patients displayed 130 hypointense lesions on MRI and only nine showed no hypointense lesions. In total, 17 (13.1%) of 130 hypointense lesions on MRI developed into classical HCC. The cumulative rates for these lesions to develop into classical HCC were 3.2% at 1 year, 11.1% at 2 years and 15.9% at 3 years. The total occurrence rates of classical HCC (25.8% at 1 year, 52.6% at 2 years and 76.4% at 3 years) were higher compared to those regarding only occurrence of classical HCC from hypointense lesions on MRI (10.0% at 1 year, 35.6% at 2 years and 44.6% at 3 years), although no significant difference was observed (p=0.073). CONCLUSIONS: Hypointense lesions that are detected in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI have some malignant potential, although treating these lesions aggressively in patients who already have HCC may be too severe.

Precision of the measurement of CT numbers: comparison of dual-energy CT spectral imaging with fast kVp switching and conventional CT with phantoms.

PURPOSE: To compare dual-energy computed tomography (CT) spectral imaging and conventional CT imaging in terms of precision of the measurement of CT numbers in phantoms. MATERIALS AND METHODS: A circular phantom (CP) and an elliptical phantom (EP) were used. Capsules filled with iodine contrast media solutions at various concentration levels were placed in the phantoms. Conventional CT was performed at a tube voltage of 120 kVp. Simulated monochromatic images at 65 keV were obtained by dual-energy CT spectral imaging. The CT number of each iodine capsule was measured. A linear regression model was used to evaluate linearity, while analysis of covariance was used to investigate the degree of variability according to phantom shape for each imaging method. RESULTS: With conventional imaging, the slopes of the regression lines for CT numbers measured at the EP center and EP periphery were significantly lower than those measured for CP (P < 0.0001 for both EP center vs. CP and for EP periphery vs. CP). No significant difference in slope was found among phantom shapes in dual-energy spectral CT imaging. CONCLUSION: Computed tomography numbers varied considerably depending on the phantom shape in conventional CT, whereas dual-energy CT provided consistent CT numbers regardless of the phantom shape.

Comparison of CT findings of biliary tract changes with autoimmune pancreatitis and extrahepatic bile duct cholangiocarcinoma.

PURPOSE: To retrospectively evaluate criteria for differentiating biliary tract changes in autoimmune pancreatitis (AIP-BTC) from extrahepatic cholangiocarcinoma (ECCA) based on CT findings and to determine predictors for differentiation between the two disorders. MATERIALS AND METHODS: CT findings of 22 patients with AIP-BTC and 45 patients with ECCA, both with positive CT findings in the biliary system, were retrospectively assessed. The images were assessed for presence of biliary obstruction, diameter of the maximally dilated biliary duct, maximum thickness of the involved duct, presence of masses inside or around the involved ducts, lengths of the biliary lesions, concentricity of wall thickening, multifocality of the lesion, and degree of lesion enhancement. RESULTS: Compared with AIP-BTC, ECCA was significantly more frequently associated with biliary obstruction (p = 0.0037), shorter lengths of the biliary lesions (p = 0.0036), and masses (p < 0.001). No significant differences were found for other items. CONCLUSION: Presence of obstructive dilatation of the bile ducts and intraluminal or peri-ductal masses and length of the thickened wall may help differentiate between AIP-BTC and ECCA.

Radiology reading-caused fatigue and measurement of eye strain with critical flicker fusion frequency.

PURPOSE: The aim of this study was to investigate eye fatigue that could impair diagnostic accuracy by measuring the critical flicker fusion frequency (CFFF) before and after reading. MATERIALS AND METHODS: CFFF was measured before and after about 4 h of health checkup reading in seven healthy volunteer radiologists. A questionnaire was also completed on duration of sleep the night before the experiment, average duration of sleep, and subjective fatigue using a visual analog scale (corrected to a 0-1 scale, 0 indicating the worst fatigue ever experienced). RESULTS: After-reading subjective fatigue was significantly greater (before 0.52 ± 0.15, after 0.42 ± 0.15), and CFFF was significantly lower (before 40.9 ± 2.4, after 39.9 ± 2.0). There was no significant correlation between subjective fatigue and CFFF, either before or after or between before- and after-reading differences in subjective fatigue and CFFF. Shorter duration of sleep the night before significantly correlated with lower CFFF (Pearson's correlation coefficient): before 0.42, P = 0.0047; after 0.52, P = 0.0003. CONCLUSION: CFFF declines after reading and can be considered useful as an indicator of fatigue induced by radiology reading. CFFF declines significantly when sleep is reduced the day before reading without correlation with subjective fatigue, meaning that sleep deprivation can cause an unaware decline in visual function.

Detection of hepatocellular carcinoma by Gd-EOB-DTPA-enhanced liver MRI: comparison with triple phase 64 detector row helical CT.

PURPOSE: To compare the diagnostic performance of Gd-EOB-DTPA-enhanced MRI with that of triple phase 64-MDCT in the detection of hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Thirty-four patients with 52 surgically proven lesions underwent Gd-EOB-DTPA-enhanced MRI and triple phase 64-MDCT. Two observers independently evaluated MR and CT imaging on a lesion-by-lesion basis. Sensitivity, positive and negative predictive values and reproducibility were evaluated. The diagnostic accuracy of each modality was assessed with alternative-free response receiver operating characteristic (ROC) analysis. RESULTS: Both observers showed higher sensitivity in detecting lesions with MRI compared to CT, however, only the difference between the two imaging techniques for observer 2 was significant (P=0.034). For lesions 1cm or smaller, MRI and CT showed equal sensitivity (both 62.5%) with one observer, and MRI proved superior to CT with the other observer (MRI 75% vs. CT 56.3%), but the latter difference was not significant (P=0.083). The difference in positive and negative predictive value between the two imaging techniques for each observer was not significant (P>0.05). The areas under the ROC curve for each observer were 0.843 and 0.861 for MRI vs. 0.800 and 0.833 for CT and the differences were not significant. Reproducibility was higher using MRI for both observers, but the result was not significant (MRI 32/33 vs. CT 29/33, P=0.083). CONCLUSION: Gd-EOB-DTPA-enhanced MRI tended to show higher diagnostic accuracy, sensitivity and reproducibility compared to triple phase 64-MDCT in the detection of hepatocellular carcinoma, however statistical significance was not achieved.

Adaptive statistical iterative reconstruction for volume-rendered computed tomography portovenography: improvement of image quality.

PURPOSE: Adaptive statistical iterative reconstruction (ASIR) is a reconstruction technique for computed tomography (CT) that reduces image noise. The purpose of our study was to investigate whether ASIR improves the quality of volume-rendered (VR) CT portovenography. MATERIALS AND METHODS: Institutional review board approval, with waived consent, was obtained. A total of 19 patients (12 men, 7 women; mean age 69.0 years; range 25-82 years) suspected of having liver lesions underwent three-phase enhanced CT. VR image sets were prepared with both the conventional method and ASIR. The required time to make VR images was recorded. Two radiologists performed independent qualitative evaluations of the image sets. The Wilcoxon signed-rank test was used for statistical analysis. Contrast-noise ratios (CNRs) of the portal and hepatic vein were also evaluated. RESULTS: Overall image quality was significantly improved by ASIR (P < 0.0001 and P = 0.0155 for each radiologist). ASIR enhanced CNRs of the portal and hepatic vein significantly (P < 0.0001). The time required to create VR images was significantly shorter with ASIR (84.7 vs. 117.1 s; P = 0.014). CONCLUSION: ASIR enhances CNRs and improves image quality in VR CT portovenography. It also shortens the time required to create liver VR CT portovenographs.