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1.
Background
Computed tomography (CT) for evaluation of occult and suspect hip fractures has been proposed as a good second-line investigation. The diagnostic precision compared to magnetic resonance imaging (MRI) is unclear.Purpose
To compare the diagnostic performance of CT and MRI in a retrospective study on patients with suspect and occult hip fractures.Material and methods
Forty-four elderly consecutive patients with low-energy trauma to the hip were identified where negative or suspect CT was followed by MRI. Primary reporting and review by two observers as well as the diagnostic performance of the two modalities were compared. Surgical treatment and clinical course were used as outcomes.Results
Compared to the primary reports, the CT reviewers found fewer normal and no suspect cases. MRI changed the primary diagnoses in 27 cases, and in 14 and 15 cases, respectively, at review. There was no disagreement on MRI diagnoses.Conclusion
In our patient population, MRI was deemed a more reliable modality for hip fracture diagnosis in comparison to CT. For clinical decision making, MRI seems to have a higher accuracy than CT. A negative CT finding cannot completely rule out a hip fracture in patients where clinical findings of hip fracture persevere.Key Points
? Experience is highly influential in diagnosing occult or suspect hip fractures at CT ? Inconclusive hip CT shows high inter-rater reliability at experienced review ? There was low diagnostic accuracy via CT compared to MRI for all interpreters ? Hip fractures can readily be diagnosed at MRI regardless of radiological experience2.
Jung Won Moon Jang Pyo Bae Ho Yun Lee Namkug Kim Man Pyo Chung Hye Yun Park Yongjun Chang Joon Beom Seo Kyung Soo Lee 《European radiology》2016,26(5):1368-1377
Objectives
To evaluate automated texture-based segmentation of dual-energy CT (DECT) images in diffuse interstitial lung disease (DILD) patients and prognostic stratification by overlapping morphologic and perfusion information of total lung.Methods
Suspected DILD patients scheduled for surgical biopsy were prospectively included. Texture patterns included ground-glass opacity (GGO), reticulation and consolidation. Pattern- and perfusion-based CT measurements were assessed to extract quantitative parameters. Accuracy of texture-based segmentation was analysed. Correlations between CT measurements and pulmonary function test or 6-minute walk test (6MWT) were calculated. Parameters of idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP) and non-IPF/UIP were compared. Survival analysis was performed.Results
Overall accuracy was 90.47 % for whole lung segmentation. Correlations between mean iodine values of total lung, 50–97.5th (%) attenuation and forced vital capacity or 6MWT were significant. Volume of GGO, reticulation and consolidation had significant correlation with DLco or SpO2 on 6MWT. Significant differences were noted between IPF/UIP and non-IPF/UIP in 6MWT distance, mean iodine value of total lung, 25–75th (%) attenuation and entropy. IPF/UIP diagnosis, GGO ratio, DILD extent, 25–75th (%) attenuation and SpO2 on 6MWT showed significant correlations with survival.Conclusion
DECT combined with pattern analysis is useful for analysing DILD and predicting survival by provision of morphology and enhancement.Key Points
? Dual-energy CT (DECT) produces morphologic and parenchymal enhancement information. ? Automated lung segmentation enables analysis of disease extent and severity. ? This prospective study showed value of DECT in DILD patients. ? Parameters on DECT enable characterization and survival prediction of DILD.3.
Objectives
To investigate the effect of iodine uptake on tissue/organ absorbed doses from CT exposure and its implications in CT dosimetry.Methods
The contrast-induced CT number increase of several radiosensitive tissues was retrospectively determined in 120 CT examinations involving both non-enhanced and contrast-enhanced CT imaging. CT images of a phantom containing aqueous solutions of varying iodine concentration were obtained. Plots of the CT number increase against iodine concentration were produced. The clinically occurring iodine tissue uptake was quantified by attributing recorded CT number increase to a certain concentration of aqueous iodine solution. Clinically occurring iodine uptake was represented in mathematical anthropomorphic phantoms. Standard 120 kV CT exposures were simulated using Monte Carlo methods and resulting organ doses were derived for non-enhanced and iodine contrast-enhanced CT imaging.Results
The mean iodine uptake range during contrast-enhanced CT imaging was found to be 0.02-0.46% w/w for the investigated tissues, while the maximum value recorded was 0.82% w/w. For the same CT exposure, iodinated tissues were found to receive higher radiation dose than non-iodinated tissues, with dose increase exceeding 100% for tissues with high iodine uptake.Conclusions
Administration of iodinated contrast medium considerably increases radiation dose to tissues from CT exposure.Key-points
? Radiation absorption ability of organs/tissues is considerably affected by iodine uptake ? Iodinated organ/tissues may absorb up to 100?% higher radiation dose ? Compared to non-enhanced, contrast-enhanced CT may deliver higher dose to patient tissues ? CT dosimetry of contrast-enhanced CT imaging should encounter tissue iodine uptake4.
G. J. Wengert T. H. Helbich R. Woitek P. Kapetas P. Clauser P. A. Baltzer W-D. Vogl M. Weber A. Meyer-Baese Katja Pinker 《European radiology》2016,26(11):3917-3922
Purpose
To evaluate the inter-/intra-observer agreement of BI-RADS-based subjective visual estimation of the amount of fibroglandular tissue (FGT) with magnetic resonance imaging (MRI), and to investigate whether FGT assessment benefits from an automated, observer-independent, quantitative MRI measurement by comparing both approaches.Materials and methods
Eighty women with no imaging abnormalities (BI-RADS 1 and 2) were included in this institutional review board (IRB)-approved prospective study. All women underwent un-enhanced breast MRI. Four radiologists independently assessed FGT with MRI by subjective visual estimation according to BI-RADS. Automated observer-independent quantitative measurement of FGT with MRI was performed using a previously described measurement system. Inter-/intra-observer agreements of qualitative and quantitative FGT measurements were assessed using Cohen’s kappa (k).Results
Inexperienced readers achieved moderate inter-/intra-observer agreement and experienced readers a substantial inter- and perfect intra-observer agreement for subjective visual estimation of FGT. Practice and experience reduced observer-dependency. Automated observer-independent quantitative measurement of FGT was successfully performed and revealed only fair to moderate agreement (k?=?0.209–0.497) with subjective visual estimations of FGT.Conclusion
Subjective visual estimation of FGT with MRI shows moderate intra-/inter-observer agreement, which can be improved by practice and experience. Automated observer-independent quantitative measurements of FGT are necessary to allow a standardized risk evaluation.Key Points
? Subjective FGT estimation with MRI shows moderate intra-/inter-observer agreement in inexperienced readers.? Inter-observer agreement can be improved by practice and experience. ? Automated observer-independent quantitative measurements can provide reliable and standardized assessment of FGT with MRI.5.
Objectives
To compare the performance of on-site quick cortisol assay (QCA) and C-arm computed tomography (CT) assistance on adrenal venous sampling (AVS) without adrenocorticotropic hormone stimulation.Methods
The institutional review board at our hospital approved this retrospective study, which included 178 consecutive patients with primary aldosteronism. During AVS, we used C-arm CT to confirm right adrenal cannulation between May 2012 and June 2015 (n = 100) and QCA for bilateral adrenal cannulation between July 2015 and September 2016 (n = 78). Successful AVS required a selectivity index (cortisoladrenal vein/cortisolperipheral) of ≥ 2.0 bilaterally.Results
The overall success rate of C-arm CT-assisted AVS was 87%, which increased to 97.4% under QCA (P = .013). The procedure time (C-arm CT, 49.5 ± 21.3 min; QCA, 37.5 ± 15.6 min; P < .001) and radiation dose (C-arm CT, 673.9 ± 613.8 mGy; QCA, 346.4 ± 387.8 mGy; P < .001) were also improved. The resampling rate was 16% and 21.8% for C-arm CT and QCA, respectively. The initial success rate of the performing radiologist remained stable during the study period (C-arm CT 75%; QCA, 82.1%, P = .259).Conclusions
QCA might be superior to C-arm CT for improving the performance of AVS.Key Points
? Adrenal venous sampling (AVS) is a technically challenging procedure. ? C-arm CT and quick cortisol assay (QCA) are efficient for assisting AVS. ? QCA might outperform C-arm CT in enhancing AVS performance.6.
Purpose
To describe imaging findings of arterial hypervascular solid-appearing serous cystic neoplasms (SCNs) of the pancreas on CT and MR and determine imaging features differentiating them from neuroendocrine tumours (NETs).Materials and methods
We retrospectively identified 15 arterial hypervascular solid-appearing SCNs and randomly chose 30 size-matched pancreatic NETs. On CT, two radiologists in consensus assessed the size, morphology, and CT attenuation. On MR, predominant signal intensity and the amount of the cystic component on T2-weighted images and ADC maps were evaluated and compared using Fisher’s exact and Student’s t-test.Results
The mean SCN size was 2.6 cm (range, 0.8–8.3). The CT findings were similar between the two tumours: location, shape, margin, and enhancement pattern. SCNs were significantly more hypodense on non-enhanced CT images than NETs (P?=?.03). They differed significantly on MR: bright signal intensity (P?=?.01) and more than a 10 % cystic component on T2-weighted images (P?=?.01) were more common in SCNs than in NETs. All SCNs showed a non-restrictive pattern on the ADC map, while NETs showed diffusion restriction (P?<?.01).Conclusion
Arterial hypervascular solid-appearing SCNs and NETs share similar imaging features. Non-enhanced CT and MR images with T2-weighted images and ADC maps can facilitate the differentiation.Key points
? Frequency of hypervascular solid-appearing SCNs was 7.3?% among surgically confirmed SCNs.? Hypervascular solid-appearing SCN of the pancreas can mimic pancreatic NETs.? Unenhanced CT and MR features help to differentiate the two tumours.7.
Objectives
To determine the diagnostic value of the cotton ball sign and other CT features in patients with gallbladder (GB) wall thickenings (WTs).Methods
Three blinded readers reviewed the preoperative CT and MR images of 101 patients with pathologically confirmed GB adenomyomatosis (GA) (n = 34) and other benign (n = 29), malignant (n = 41), and premalignant (n = 2) GBWTs. Three readers analysed the morphological features of GBWT and presence of the “cotton ball sign”, defined as fuzzy grey dots in GBWT or a dotted outer border of the inner enhancing layer on contrast-enhanced (CE) CT. In addition, the “pearl necklace sign” on MR was analysed.Results
In the GA group (n = 34), prevalence of the cotton ball sign and pearl necklace sign was 74% (25/34) and 44% (15/34), respectively. Presence of the cotton ball sign, smooth contour of the mucosa, double-layering enhancement, and enhancement degree weaker than the renal cortex on CT images were significant predictors of benign GBWT (p < 0.01). When differentiating GA from GB malignancy or premalignancy, accuracy of the cotton ball sign and pearl necklace sign was 81% (62/77) and 74% (57/77), respectively.Conclusion
The cotton ball sign on CE-CT showed higher sensitivity and comparable specificity to those of the pearl necklace sign in differentiating GA from malignancy.Key Points
? Prevalence of the cotton ball sign on CT was 74% in gallbladder adenomyomatosis. ? The cotton ball sign was useful in differentiating gallbladder adenomyomatosis from gallbladder cancer. ? The cotton ball sign was more sensitive than the pearl necklace sign for adenomyomatosis diagnosis.8.
Purpose
This work provides detailed estimates of the foetal dose from diagnostic CT imaging of pregnant patients to enable the assessment of the diagnostic benefits considering the associated radiation risks.Materials and methods
To produce realistic biological and physical representations of pregnant patients and the embedded foetus, we developed a methodology for construction of patient-specific voxel-based computational phantoms based on existing standardised hybrid computational pregnant female phantoms. We estimated the maternal absorbed dose and foetal organ dose for 30 pregnant patients referred to the emergency unit of Geneva University Hospital for abdominal CT scans.Results
The effective dose to the mother varied from 1.1 mSv to 2.0 mSv with an average of 1.6 mSv, while commercial dose-tracking software reported an average effective dose of 1.9 mSv (range 1.7–2.3 mSv). The foetal dose normalised to CTDIvol varies between 0.85 and 1.63 with an average of 1.17.Conclusion
The methodology for construction of personalised computational models can be exploited to estimate the patient-specific radiation dose from CT imaging procedures. Likewise, the dosimetric data can be used for assessment of the radiation risks to pregnant patients and the foetus from various CT scanning protocols, thus guiding the decision-making process.Key points
? In CT examinations, the absorbed dose is non-uniformly distributed within foetal organs. ? This work reports, for the first time, estimates of foetal organ-level dose. ? The foetal brain and skeleton doses present significant correlation with gestational age. ? The conceptus dose normalised to CTDI vol varies between 0.85 and 1.63. ? The developed methodology is adequate for patient-specific CT radiation dosimetry.9.
Objectives
To evaluate the impact of CT scans on diagnosis or change of therapy in patients with systemic inflammatory response syndrome (SIRS) or sepsis and obscure clinical infection.Methods
CT records of patients with obscure clinical infection and SIRS or sepsis were retrospectively evaluated. Both confirmation of and changes in the diagnosis or therapy based on CT findings were analysed by means of the hospital information system and radiological information system. A sub-group analysis included differences with regard to anatomical region, medical history and referring department.Results
Of 525 consecutive patients evaluated, 59% had been referred from internal medicine and 41% from surgery. CT examination had confirmed the suspected diagnosis in 26% and had resulted in a different diagnosis in 33% and a change of therapy in 32%. Abdominal scans yielded a significantly higher (p=0.013) change of therapy rate (42%) than thoracic scans (22%). Therapy was changed significantly more often (p=0.016) in surgical patients (38%) than in patients referred from internal medicine (28%).Conclusions
CT examination for detecting an unknown infection focus in patients with SIRS or sepsis is highly beneficial and should be conducted in patients with obscure clinical infection.Key Points
? Evaluation of patients with obscure clinical infection is a challenging task. ? CT examination of patients with SIRS or sepsis seems to be beneficial. ? CT examination confirmed suspected diagnosis in 26% of patients. ? CT examination yielded a new infection focus in 33% of patients. ? CT examination changed therapy in up to 32% of patients.10.
Yong?Zhu Jun?Chen Weiwei?Kong Liang?Mao Wentao?Kong Qun?Zhou Zhengyang?Zhou Bin?Zhu Zhongqiu?Wang Jian?He
Objectives
To explore the difference in contrast-enhanced computed tomography (CT) features of intrahepatic cholangiocarcinomas (ICCs) with different isocitrate dehydrogenase (IDH) mutation status.Methods
Clinicopathological and contrast-enhanced CT features of 78 patients with 78 ICCs were retrospectively analysed and compared based on IDH mutation status.Results
There were 11 ICCs with IDH mutation (11/78, 14.1%) and 67 ICCs without IDH mutation (67/78, 85.9%). IDH-mutated ICCs showed intratumoral artery more often than IDH-wild ICCs (p?=?0.023). Most ICCs with IDH mutation showed rim and internal enhancement (10/11, 90.9%), while ICCs without IDH mutation often appeared diffuse (26/67, 38.8%) or with no enhancement (4/67, 6.0%) in the arterial phase (p?=?0.009). IDH-mutated ICCs showed significantly higher CT values, enhancement degrees and enhancement ratios in arterial and portal venous phases than IDH-wild ICCs (all p?<?0.05). The CT value of tumours in the portal venous phase performed best in distinguishing ICCs with and without IDH mutation, with an area under the curve of 0.798 (p?=?0.002).Conclusions
ICCs with and without IDH mutation differed significantly in arterial enhancement mode, and the tumour enhancement degree on multiphase contrast-enhanced CT was helpful in predicting IDH mutation status.Key Points
? IDH mutation occurred frequently in ICCs. ? ICCs with and without IDH mutation differed significantly in arterial enhancement mode. ? ICCs with IDH mutation enhanced more than those without IDH mutation. ? Enhancement ratio and tumour CT value can predict IDH mutation status.11.
Objectives
To deploy and evaluate a stereological point-counting technique on abdominal CT for the estimation of visceral (VAF) and subcutaneous abdominal fat (SAF) volumes.Methods
Stereological volume estimations based on point counting and systematic sampling were performed on images from 14 consecutive patients who had undergone abdominal CT. For the optimization of the method, five sampling intensities in combination with 100 and 200 points were tested. The optimum stereological measurements were compared with VAF and SAF volumes derived by the standard technique of manual planimetry on the same scans.Results
Optimization analysis showed that the selection of 200 points along with the sampling intensity 1/8 provided efficient volume estimations in less than 4 min for VAF and SAF together. The optimized stereology showed strong correlation with planimetry (VAF: r?=?0.98; SAF: r?=?0.98). No statistical differences were found between the two methods (VAF: P?=?0.81; SAF: P?=?0.83). The 95 % limits of agreement were also acceptable (VAF: ?16.5 %, 16.1 %; SAF: ?10.8 %, 10.7 %) and the repeatability of stereology was good (VAF: CV?=?4.5 %, SAF: CV?=?3.2 %).Conclusions
Stereology may be successfully applied to CT images for the efficient estimation of abdominal fat volume and may constitute a good alternative to the conventional planimetric technique.Key Points:
? Abdominal obesity is associated with increased risk of disease and mortality. ? Stereology may quantify visceral and subcutaneous abdominal fat accurately and consistently. ? The application of stereology to estimating abdominal volume fat reduces processing time. ? Stereology is an efficient alternative method for estimating abdominal fat volume.12.
Dong Wook Kim Hyoung Jung Kim Kyung Won Kim Jae Ho Byun So Yeon Kim Ki Byung Song Nikhil H. Ramaiya Sree Harsha Tirumani Seung-Mo Hong 《European radiology》2016,26(5):1320-1329
Objectives
To evaluate the prognostic value of CT to predict recurrence-free and overall survival in patients with pancreatic neuroendocrine neoplasms (PanNENs).Methods
Between January 2004 and December 2012, 161 consecutive patients who underwent preoperative triphasic CT and surgical resection with curative intent for PanNENs were identified. The tumour consistency, margin, presence of calcification, pancreatic duct dilatation, bile duct dilatation, vascular invasion, and hepatic metastases were evaluated. The tumour size, arterial enhancement ratio, and portal enhancement ratio were measured. The Cox proportional hazard model was used to determine the association between CT features and recurrence-free survival and overall survival.Results
By multivariate analysis, tumour size (>3 cm) (hazard ratio, 3.314; p?=?0.006), portal enhancement ratio (≤1.1) (hazard ratio, 2.718; p?=?0.006), and hepatic metastases (hazard ratio, 4.374; p?=?0.003) were independent significant variables for worse recurrence-free survival. Portal enhancement ratio (≤1.1) (hazard ratio, 5.951; p?=?0.001) and hepatic metastases (hazard ratio, 4.122; p?=?0.021) were independent significant variables for worse overall survival.Conclusions
Portal enhancement ratio (≤1.1) and hepatic metastases assessed on CT were common independent prognostic factors for worse recurrence-free survival and overall survival in patients with PanNENs.Key points
? CT is useful to predict survival outcomes in patients with PanNENs.? Survival outcomes are associated with portal enhancement ratio and hepatic metastases.? Portal enhancement ratio is prognostic CT biomarker in patients with PanNENs.13.
Sang Min Lee Jin Mo Goo Chang Min Park Soon Ho Yoon Jin Chul Paeng Gi Jeong Cheon Young Tae Kim Young Sik Park 《European radiology》2016,26(11):3850-3857
Objectives
To prospectively compare the accuracies of PET/MR and PET/CT in the preoperative staging of non-small cell lung cancer (NSCLC).Methods
Institutional review board approval and patients’ informed consents were obtained. 45 patients with proven or radiologically suspected lung cancer which appeared to be resectable on CT were enrolled. PET/MR was performed for the preoperative staging of NSCLC followed by PET/CT without contrast enhancement on the same day. Dedicated MR images including diffusion weighted images were obtained. Readers assessed PET/MR and PET/CT with contrast-enhanced CT. Accuracies of PET/MR and PET/CT for NSCLC staging were compared.Results
Primary tumour stages (n?=?40) were correctly diagnosed in 32 patients (80.0 %) on PET/MR and in 32 patients (80.0 %) on PET/CT (P?=?1.0). Node stages (n?=?42) were correctly determined in 24 patients (57.1 %) on PET/MR and in 22 patients (52.4 %) on PET/CT (P?=?0.683). Metastatic lesions in the brain, bone, liver, and pleura were detected in 6 patients (13.3 %). PET/MR missed one patient with pleural metastasis while PET/CT missed one patient with solitary brain metastasis and two patients with pleural metastases (P?=?0.480).Conclusions
This study demonstrated that PET/MR in combination with contrast-enhanced CT was comparable to PET/CT in the preoperative staging of NSCLC while reducing radiation exposure.Key points
? PET/MR can be comparable to PET/CT for preoperative NSCLC staging.? PET/MR and PET/CT show excellent correlation in measuring SUVmax of primary lesions.? Using PET/MR, estimated radiation dose can decrease by 31.1?% compared with PET/CT.14.
Grigorios-Aris Cheimariotis Mariam Al-Mashat Kostas Haris Anthony H. Aletras Jonas Jögi Marika Bajc Nicolaos Maglaveras Einar Heiberg 《Annals of nuclear medicine》2018,32(2):94-104
Objective
Image segmentation is an essential step in quantifying the extent of reduced or absent lung function. The aim of this study is to develop and validate a new tool for automatic segmentation of lungs in ventilation and perfusion SPECT images and compare automatic and manual SPECT lung segmentations with reference computed tomography (CT) volumes.Methods
A total of 77 subjects (69 patients with obstructive lung disease, and 8 subjects without apparent perfusion of ventilation loss) performed low-dose CT followed by ventilation/perfusion (V/P) SPECT examination in a hybrid gamma camera system. In the training phase, lung shapes from the 57 anatomical low-dose CT images were used to construct two active shape models (right lung and left lung) which were then used for image segmentation. The algorithm was validated in 20 patients, comparing its results to reference delineation of corresponding CT images, and by comparing automatic segmentation to manual delineations in SPECT images.Results
The Dice coefficient between automatic SPECT delineations and manual SPECT delineations were 0.83?±?0.04% for the right and 0.82?±?0.05% for the left lung. There was statistically significant difference between reference volumes from CT and automatic delineations for the right (R?=?0.53, p?=?0.02) and left lung (R?=?0.69, p?<?0.001) in SPECT. There were similar observations when comparing reference volumes from CT and manual delineations in SPECT images, left lung (bias was ??10?±?491, R?=?0.60, p?=?0.005) right lung (bias 36?±?524 ml, R?=?0.62, p?=?0.004).Conclusion
Automated segmentation on SPECT images are on par with manual segmentation on SPECT images. Relative large volumetric differences between manual delineations of functional SPECT images and anatomical CT images confirms that lung segmentation of functional SPECT images is a challenging task. The current algorithm is a first step towards automatic quantification of wide range of measurements.15.
Objectives
To investigate the radiological findings prognostic for the development of pancreatic adenocarcinoma in a cohort of patients with hepatocellular carcinoma, using multiphasic computed tomography (CT).Methods
A case–cohort study performed in a single university hospital. A database of patients who received hepatocellular carcinoma (HCC) treatment and trimonthly follow-up with four-phase dynamic CT was used (n = 1848). The cohort group was randomly extracted from the database (n = 103). The case group comprised nine patients from the database who developed pancreatic adenocarcinoma. The radiological findings were assessed during follow-up (average, 32 months).Results
The incidence of pancreatic mass, inhomogeneous parenchyma, loss of fatty marbling and main pancreatic duct dilatation gradually increased from 4 to 13 months before the diagnosis of pancreatic adenocarcinoma. There was a significantly higher incidence of pancreatic mass, inhomogeneous parenchyma and loss of fatty marbling on CT at baseline (average, 34 months before diagnosis) in the case group compared with the cohort group (P values < 0.01) and those findings at baseline were revealed as prognostic factors for pancreatic carcinogenesis, respectively (log-rank test, P values < 0.001).Conclusions
Several radiological findings observed on multiphasic CT can assist in predicting pancreatic carcinogenesis well in advance.Key points
? Pancreatic findings in multiphasic CT help predict development of pancreatic adenocarcinoma. ? Key findings are mass, inhomogeneous parenchyma and loss of fatty marbling. ? Those findings were observed 34 months before confirmed diagnosis of adenocarcinoma. ? Those findings were prognostic factors for pancreatic carcinogenesis.16.
Objectives
To systematically explore the lowest reasonably achievable radiation dose for appendiceal CT using an iterative reconstruction (IR) in young adults.Methods
We prospectively included 30 patients who underwent 2.0-mSv CT for suspected appendicitis. From the helical projection data, 1.5-, 1.0- and 0.5-mSv CTs were generated using a low-dose simulation tool and the knowledge-based IR. We performed step-wise non-inferiority tests sequentially comparing 2.0-mSv CT with each of 1.5-, 1.0- and 0.5-mSv CT, with a predetermined non-inferiority margin of 0.06. The primary end point was the pooled area under the receiver-operating-characteristic curve (AUC) for three abdominal and three non-abdominal radiologists.Results
For the abdominal radiologists, the non-inferiorities of 1.5-, 1.0- and 0.5-mSv CT to 2.0-mSv CT were sequentially accepted [pooled AUC difference: 2.0 vs. 0.5 mSv, 0.017 (95% CI: -0.016, 0.050)]. For the non-abdominal radiologists, the non-inferiorities of 1.5- and 1.0-mSv CT were accepted; however, the non-inferiority of 0.5-mSv CT could not be proved [pooled AUC difference: 2.0 vs. 1.0 mSv, -0.017 (-0.070, 0.035) and 2.0 vs. 0.5 mSv, 0.045 (-0.071, 0.161)].Conclusion
The 1.0-mSv appendiceal CT was non-inferior to 2.0-mSv CT in terms of diagnostic performance for both abdominal and non-abdominal radiologists; 0.5-mSv appendiceal CT was non-inferior only for abdominal radiologists.Key points
? For both abdominal and non-abdominal radiologists, 1.0-mSv appendiceal CT could be feasible. ? The 0.5-mSv CT was non-inferior to 2.0-mSv CT only for expert abdominal radiologists. ? Reader experience is an important factor affecting diagnostic impairment by low-dose CT.17.
Objectives
To determine if identifiable hepatic textural features are present at abdominal CT in patients with colorectal cancer (CRC) prior to the development of CT-detectable hepatic metastases.Methods
Four filtration–histogram texture features (standard deviation, skewness, entropy and kurtosis) were extracted from the liver parenchyma on portal venous phase CT images at staging and post-treatment surveillance. Surveillance scans corresponded to the last scan prior to the development of CT-detectable CRC liver metastases in 29 patients (median time interval, 6 months), and these were compared with interval-matched surveillance scans in 60 CRC patients who did not develop liver metastases. Predictive models of liver metastasis-free survival and overall survival were built using regularised Cox proportional hazards regression.Results
Texture features did not significantly differ between cases and controls. For Cox models using all features as predictors, all coefficients were shrunk to zero, suggesting no association between any CT texture features and outcomes. Prognostic indices derived from entropy features at surveillance CT incorrectly classified patients into risk groups for future liver metastases (p < 0.001).Conclusions
On surveillance CT scans immediately prior to the development of CRC liver metastases, we found no evidence suggesting that changes in identifiable hepatic texture features were predictive of their development.Key Points
? No correlation between liver texture features and metastasis-free survival was observed. ? Liver texture features incorrectly classified patients into risk groups for liver metastases. ? Standardised texture analysis workflows need to be developed to improve research reproducibility.18.
Objectives
In this study, we aimed to determine whether iterative model reconstruction designed for brain CT (IMR-neuro) would improve the accuracy of posterior fossa stroke diagnosis on brain CT.Methods
We enrolled 37 patients with ischaemic stroke in the posterior fossa and 37 patients without stroke (controls). Using axial images reconstructed using filtered back-projection (FBP) and IMR-neuro, we compared the CT numbers in infarcted areas, image noise in the pons, and contrast-to-noise ratios (CNRs) of infarcted and non-infarcted areas on scans subjected to IMR-neuro and FBP. To analyse the performance of hypo-attenuation detection, we used receiver-operating characteristic (ROC) curve techniques.Results
The image noise was significantly lower (2.2?±?0.5 vs. 5.1?±?0.9 Hounsfield units, p?<?0.01) and the difference in CNR between the infarcted and non-infarcted areas was significantly higher with IMR-neuro than with FBP (2.2?±?1.7 vs. 4.0?±?3.6, p?<?0.01). Furthermore, the average area under the ROC curve was significantly higher with IMR-neuro (0.90 vs. 0.86 for FBP, p?=?0.04).Conclusion
IMR-neuro yielded better image quality and improved hypo-attenuation detection in patients with ischaemic stroke.Key points
? Iterative model reconstruction of brain CT data can facilitate the diagnosis of ischaemic stroke.? IMR improved the detectability of low-contrast lesions in the posterior fossa.? IMR-neuro yielded better image quality and improved observer performance.19.
Purpose
To investigate staging accuracy of multidetector CT (MDCT) for pancreatic neuroendocrine tumour (PNET) and diagnostic performance for differentiation of PNET from pancreatic adenocarcinoma.Material and methods
We included 109 patients with surgically proven PNET (NETG1?=?66, NETG2?=?31, NEC?=?12) who underwent MDCT. Two reviewers assessed stage and presence of predefined CT findings. We analysed the relationship between CT findings and tumour grade. Using PNETs with uncommon findings, we also estimated the possibility of PNET or adenocarcinoma.Results
Accuracy for T stage was 85–88 % and N-metastasis was 83–89 %. Common findings included well circumscribed, homogeneously enhanced, hypervascular mass, common in lower grade tumours (p?<?0.05). Uncommon findings included ill-defined, heterogeneously enhanced, hypovascular mass and duct dilation, common in higher grade tumours (p?<?0.05). Using 31 PNETs with uncommon findings, diagnostic performance for differentiation from adenocarcinoma was 0.760–0.806. Duct dilatation was an independent predictor for adenocarcinoma (Exp(B)?=?4.569). PNETs with uncommon findings were associated with significantly worse survival versus PNET with common findings (62.7 vs. 95.7 months, p?<?0.001).Conclusion
MDCT is useful for preoperative evaluation of PNET; it not only accurately depicts the tumour stage but also prediction of tumour grade, because uncommon findings were more common in higher grade tumours.Key Points
? CT accurately depicts the T stage and node metastasis of PNET. ? Uncommon findings were more common in higher grade tumours. ? CT information may be beneficial for optimal therapeutic planning.20.