Abdominal Multidetector Computed Tomography Research Articles

256‐MDCT for evaluation of urolithiasis: Iterative reconstruction allows for a significant reduction of the applied radiation dose while maintaining high subjective and objective image quality

Multidetector CT (MDCT) is the established imaging modality in diagnostics of urolithiasis. The aim of iterative reconstruction (IR) is to allow for a radiation dose reduction while maintaining high image quality. This study evaluates its performance in MDCT for assessment of urolithiasis. Fifty-two patients underwent non-contrast abdominal MDCT. Twenty-six patients were referred to MDCT under suspicion of urolithiasis, and examined using a dose-reduced scan protocol (RDCT). Twenty-six patients, who had undergone standard-dose MDCT, served as reference for radiation dose comparison. RDCT images were reconstructed using an IR system (iDose4™, Philips Healthcare, Cleveland, OH, USA). Objective image noise (OIN) was recorded and five radiologists rated the subjective image quality independently. Radiation parameters were derived from the scan protocols. The CTDIvol could be reduced by 50% to 5.8 mGy (P < 0.0001). The same reduction was achieved for DLP and effective dose to 253 ± 27 mGy*cm (P < 0.0001) and 3.9 ± 0.4 mSv (P < 0.0001). IR led to a reduction of the OIN of up to 61% compared with classic filtered back projection (FBP) (P < 0.0001). The OIN declined with increasing IR levels. RDCT with FBP showed the lowest scores of subjective image quality (2.32 ± 0.04). Mean scores improved with increasing IR levels. iDose6 was rated with the best mean score (3.66 ± 0.04). The evaluated IR-tool and protocol may be applied to achieve a considerable radiation dose reduction in MDCT for diagnostics of urolithiasis while maintaining a confident image quality. Best image quality, suitable for evaluation of the entire abdomen concerning differential diagnoses, was achieved with iDose6.

Effectiveness of noncontrast abdominal multidetector CT for evaluating the patient with renal insufficiency in the emergency department

Contrast-enhanced abdominal multidetector CT (MDCT) is an important and accurate diagnostic approach for acute abdominal symptoms or searching for an infection focus such as sepsis. But contrast dye can cause renal damage especially in critically ill patients. Noncontrast CT can be alternative options but few studies have shown the effectiveness of noncontrast MDCT. We want to evaluate the effectiveness of noncontrast abdominal MDCT in the emergency department.

MicroRNA miR-378 regulates adipocytokine fate by targeting transcriptional factors in human visceral and subctaneous adipose tissue

Purpose: MicroRNAs (miRNA), single-stranded non-protein coding gene products, regulate gene expression through post-transcriptional inhibition, and known to be involved in essential biological processes including obesity and insulin resistance. miR-378 and miR-378*, which are encoded by PGC-1β gene and counterbalance the metabolic actions of PGC-1β. Mice genetically lacking miR-378 and miR-378* are resistant to high fat diet-induced obesity and exhibit enhanced mitochondrial fatty acid metabolism and elevated oxidative capacity of insulin-target tissues. We conducted to elucidate the role of miR378 expression in human adiposity and adipose tissue inflammation. Methods: Pair samples were obtained from subcutaneous (SAT) and visceral adipose tissue (VAT) during elective operation in 71 men and 42 women. Mature miRNA levels were determined by qRT-PCR and normalized to levels of U6 small nuclear ribonucleoprotein. Subcutaneous (SFA) and visceral fat area (VFA) was determined by abdominal multidetector CT scanning. Adipocyte sizing was determined by the osmium-fixed method on a Coulter counter. Results: Study 1 (clinical study): SFA were larger than VFA, and the mean size of adipocytes was greater in SAT than in VAT. In VAT, level of log(miR100) was positively correlated with level of adiponectin, TLR4 and HMGB1, while negatively correlated with CD68, NOX4 and with mean size of adipocyte. In SAT, level of log(miR100) was positively correlated with level of IL18, TLR4 and HMGB1, while negatively correlated with NOX4. Study 2 (in vitro study): expression levels of miR100 as well as PPARγ2 and PGC1α were increased in adipocyte-like 3T3L1 cells during differentiation. Levels of PPARγ2 and PGC1α were inhibited by antisense miRNA transfection. The expression levels of computer-predicted target genes, ACSL1, acyl-CoA synthetase long-chain family member 1 and AGPAT6, 1-acylglycerol-3-phosphate O-acyltransferase 6 (lysophosphatidic acid acyltransferase ζ), were partially inhibited by anti-sense miR-378 overexpression. Conclusion: Adipose tissue miR378 is derived mostly from adipocytes and may play a role in regulating expressions of adipocyte inflammatory cytokines and insulin sensitivity in human. Results suggested that mir-378 regulates adipocytokine expression by targeting transcriptional factors and controls adipose tissue inflammation in human.

MicroRNA-100 regulates a cluster of adipocytokine expression: A human biopsy study in subcutaneous and visceral adipose tissue

Purpose: MicroRNAs (miRNA), single-stranded non-protein coding gene products, regulate gene expression through post-transcriptional inhibition, and known to be involved in essential biological processes including obesity and insulin resistance. This study was conducted to elucidate the role of miR100 expression in human adiposity and insulin resistance. Methods: Pair samples were obtained from subcutaneous (SAT) and visceral adipose tissue (VAT) during elective operation in 71 men and 42 women. Mature miRNA levels were determined by qRT-PCR and normalized to levels of U6 small nuclear ribonucleoprotein. Subcutaneous (SFA) and visceral fat area (VFA) was determined by abdominal multidetector CT scanning. Adipocyte sizing was determined by the osmium-fixed method on a Coulter counter. Results: Study 1 (clinical study): In men and women, SFA was larger than VFA, and the mean size of adipocytes was greater in SAT than in VAT. Level of log(miR100) was significantly decreased in VAT in men (p=0.025), but comparable between SAT and VAT in women. Level of log(miR100) in VAT was positively correlated with HOMA-IR, and tended to be positively correlated with expression level of macrophage marker, CD68. Level of log(miR100) in SAT was positively correlated with expression level of IL1β, NLRP3 and TLR4 in men but not in women. Study 2 (in vitro study): When stimulated with lipopolysaccharide (LPS, 1-10ng/mL), expression of miR100 was not changed in mouse macrophage-like Raw264.7 cells, but enhanced in adipocyte-like 3T3-L1 cells. A member of the NOX family of NADPH oxidases NOX4, which has a possible MiR100 target at 3'-UTR, was up-regulated in 3T3-L1 cells by LPS, but not changed in Raw264.7 cells. NOX2, another type of NADPH oxidase, was not detected in 3T3L1 cells but was in Raw264.7 cells. Conclusion: Adipose tissue miR100 is derived mostly from adipocytes and may play a direct or indirect role in regulating expressions of adipocyte inflammatory cytokines, adipocyte-specific NADPH oxidase, and insulin sensitivity in human.

Evaluation of left renal vein entrapment using multidetector computed tomography.

Nutcracker syndrome, also called left renal vein entrapment syndrome, is a cause of non-glomerular hematuria with difficulties in diagnosis. Multidetector computed tomography (MDCT) is a powerful tool to prevent unnecessary diagnostic procedures. To retrospectively determine the prevalence of nutcracker phenomenon and nutcracker syndrome seen in MDCT in consecutive patients. The institutional review board approved the study and waived the requirement for informed consent. Abdominal contrast-enhanced MDCT scans were reviewed from 1000 consecutive patients. MDCT scan assessment included renal vein diameter measurements and evaluation for the presence of anterior or posterior left renal vein entrapment. Electronic medical records and urine analysis reports of patients with left renal vein entrapment were reviewed. Student's t test was used to assess differences in renal vein diameter in patients with left renal vein entrapment. Left renal vein entrapment was observed in 10.9% (109), retro-aortic left renal vein in 6.5% (65), entrapment of left renal vein between superior mesenteric artery and aorta in 4.1% (41), and circumaortic left renal vein in 0.3% (3) of patients. Mean diameters of right (8.8 ± 1.9 mm) and unentrapped left (8.9 ± 1.8 mm) renal veins were not significantly different (P = 0.1). The mean diameter of anterior entrapped left renal veins (10.3 ± 2 mm) was significantly greater (P = 0.04) than contralateral renal veins (8.6 ± 2.1 mm) in their widest portion. In 8.8% of patients with the left renal vein entrapment, urine analysis showed isomorphic hematuria or proteinuria with no other known cause. Varicocele and pelvic congestion were seen in 5.5% of patients with the left renal vein entrapment. Left renal vein entrapment is not a rare entity and renal nutcracker phenomenon might be underdiagnosed.

Unreported Vertebral Body Compression Fractures at Abdominal Multidetector CT

To retrospectively assess the prevalence and clinical outcomes of unreported vertebral compression fractures at abdominal computed tomography (CT). This HIPAA-compliant study had institutional review board approval; the need for informed consent was waived for this retrospective analysis. A total of 2041 consecutive adult patients (1640 women, 401 men; age range, 19-94 years) underwent both abdominal multidetector CT and dual-energy x-ray absorptiometry (DXA) within 6 months of each other between 2000 and 2007, before sagittal CT reconstructions were obtained routinely. Transverse (axial) and retrospective sagittal multidetector CT reconstructions were reviewed for the presence of moderate or severe vertebral body compression fractures of the lower thoracic and lumbar spine by using the Genant visual semiquantitative method. Twenty-six patients were excluded for evidence of pathologic fracture or for technical factors limiting compression fracture detection. Electronic medical records were reviewed for patients with moderate or severe compression fractures to determine whether the fracture was reported at prospective CT interpretation, was known previously, or was diagnosed subsequently. Correlation was made with central DXA T scores. Statistical analysis was performed with the Student t test and Fisher exact test. At least one moderate or severe vertebral body compression fracture was identified retrospectively at CT in 97 patients (mean age, 70.8 years). Fractures involved one level in 67 and multiple levels in 30 patients, for a total of 141 fractures. In 81 (84%) patients, prospective CT diagnosis was not made. Patients in whom fractures were reported prospectively were significantly older and were more likely to have a severe compression fracture (P < .05). In 52 (64%) patients with an unreported fracture, the vertebral compression fracture was not known clinically. In 18 patients, subsequent diagnosis of a compression fracture was determined by means of another imaging study (median interval, 7 months). At DXA, 39 (48%) of 81 patients with unreported vertebral body compression fractures had a nonosteoporotic T score (greater than -2.5). Most clinically important vertebral body compression fractures in nontrauma patients at risk for low bone mineral density may go unreported at abdominal multidetector CT if sagittal reconstructions are not routinely evaluated.

Reduction of the Radiation Dose by Decreasing the Tube Current without Degradation of Low-Contrast Detectability on Abdominal Multi-Detector Row CT: A Phantom-Based Study

As use of the lowest acceptable radiation dose during routine diagnostic imaging is important, we determined the optimal tube current without degradation of low-contrast detectability on abdominal multi-detector row CT (MDCT). CT scanning was performed with a Catphan® 500 phantom. The optimal tube current was 300 mA on 64-MDCT and 160 mA on 8-MDCT, with a fixed voltage of 120 kV. Reduction of the radiation dose in abdominal CT scanning by lowering the tube current proved to be feasible.

Survey of pediatric MDCT radiation dose from university hospitals in Thailand: a preliminary for national dose survey

Increasing pediatric CT usage worldwide needs the optimization of CT protocol examination. Although there are previous published dose reference level (DRL) values, the local DRLs should be established to guide for clinical practice and monitor the CT radiation. To determine the multidetector CT (MDCT) radiation dose in children in three university hospitals in Thailand in four age groups using the CT dose index (CTDI) and dose length product (DLP). A retrospective review of CT dosimetry in pediatric patients (<15 years of age) who had undergone head, chest, and abdominal MDCT in three major university hospitals in Thailand was performed. Volume CTDI (CTDI(vol)) and DLP were recorded, categorized into four age groups: <1 year, 1-< 5 years, 5-<10 years, and 10-<15 years in each scanner. Range, mean, and third quartile values were compared with the national reference dose levels for CT in pediatric patients from the UK and Switzerland according to International Commission on Radiological Protection (ICRP) recommendation. Results Per age group, the third quartile values for brain, chest, and abdominal CTs were, respectively, in terms of CTDI(vol): 25, 30, 40, and 45 mGy; 4.5, 5.7, 10, and 15.6 mGy; 8.5, 9, 14, and 17 mGy; and in terms of DLP: 400, 570, 610, and 800 mGy cm; 80, 140, 305, and 470 mGy cm; and 190, 275, 560,765 mGy cm. This preliminary national dose survey for pediatric CT in Thailand found that the majority of CTDI(vol) and DLP values in brain, chest, and abdominal CTs were still below the diagnostic reference levels (DRLs) from the UK and Switzerland regarding to ICRP recommendation.

간 이식편의 체적 예측을 위한 2점 이용 간 분리

This paper proposed a method to separate a liver into left and right liver lobes for simple and exact volumetry of the river graft at abdominal MDCT(Multi-Detector Computed Tomography) image before the living donor liver transplantation. A medical team can evaluate an accurate river graft with minimized interaction between the team and a system using this algorithm for ensuring donor`s and recipient`s safe. On the image of segmented liver, 2 points(PMHV: a point in Middle Hepatic Vein and PPV: a point at the beginning of right branch of Portal Vein) are selected to separate a liver into left and right liver lobes. Middle hepatic vein is automatically segmented using PMHV, and the cutting line is decided on the basis of segmented Middle Hepatic Vein. A liver is separated on connecting the cutting line and PPV. The volume and ratio of the river graft are estimated. The volume estimated using 2 points are compared with a manual volume that diagnostic radiologist processed and estimated and the weight measured during surgery to support proof of exact volume. The mean standard deviation of the differences between the actual weights and the estimated volumes was in the case of manual segmentation and in the case of 2 points method. The correlation coefficient between the actual weight and the manually estimated volume is 0.79, and the correlation coefficient between the actual weight and the volume estimated using 2 points is 0.87. After selection the 2 points, the time involved in separation a liver into left and right river lobe and volumetry of them is measured for confirmation that the algorithm can be used on real time during surgery. The mean standard deviation of the process time is per 1 data set ().

Converted Lumbar BMD Values Derived from Sagittal Reformations of Contrast-Enhanced MDCT Predict Incidental Osteoporotic Vertebral Fractures

We obtained baseline and follow-up bone mineral density (BMD) values of the lumbar spine from sagittal reformations of routine abdominal contrast-enhanced multidetector computed tomography (MDCT) using a reference phantom and assessed their performance in differentiating patients with no, existing, and incidental osteoporotic fractures of the spine. A MDCT-to-QCT (quantitative computed tomography) conversion equation for lumbar BMD measurements was developed by using 15 postmenopausal women (63 ± 12 years), who underwent standard lumbar QCT (L1-L3) and afterward routine abdominal contrast-enhanced MDCT. Sagittal reformations were used for corresponding lumbar BMD measurements. The MDCT-to-QCT conversion equation was applied to baseline and follow-up routine abdominal contrast-enhanced MDCT scans of 149 postmenopausal women (63 ± 10 years). Their vertebral fracture status (no, existing, or incidental osteoporotic fracture) was assessed in the sagittal reformations. A correlation coefficient of r = 0.914 (p < 0.001) was calculated for the BMD values of MDCT and standard QCT with the conversion equation BMD(QCT) = 0.695 × BMD(MDCT) - 7.9 mg/mL. Mean follow-up time of the 149 patients was 20 ± 12 months. Fifteen patients (10.1 %) had an existing osteoporotic vertebral fracture at baseline. Incidental osteoporotic vertebral fractures were diagnosed in 13 patients (8.7 %). Patients with existing and incidental fractures showed significantly (p < 0.05) lower converted BMD values (averaged over L1-L3) than patients without fracture at baseline and at follow-up. In this longitudinal study, BMD values of the lumbar spine derived from sagittal reformations of routine abdominal contrast-enhanced MDCT predicted incidental osteoporotic vertebral fractures.

Virtual nonenhanced abdominal dual-energy MDCT: Analysis of image characteristics

To evaluate abdominal and pelvic image characteristics and artifacts on virtual nonenhanced (VNE) images generated from contrast-enhanced dual-energy multidetector computed tomography (MDCT) studies. Hadassah-Hebrew University Medical Institutional Review Board approval was obtained; 22 patients underwent clinically-indicated abdominal and pelvic single-source dual-energy MDCT (Philips Healthcare, Cleveland, OH, USA), pre- and post-IV administration of Omnipaque 300 contrast (100 cc). Various solid and vascular structures were evaluated. VNE images were generated from the portal contrast-enhanced phase using probabilistic separation. Contrast-enhanced-, regular nonenhanced (RNE)-, and VNE images were evaluated with a total of 1494 density measurements. The ratio of iodine contrast deletion was calculated. Visualization of calcifications, urinary tract stones, and image artifacts in VNE images were assessed. VNE images were successfully generated in all patients. Significant portal-phase iodine contrast deletion was seen in the kidney (61.7%), adrenal gland (55.3%), iliac artery (55.0%), aorta (51.6%), and spleen (34.5%). Contrast deletion was also significant in the right atrium (RA) (51.5%) and portal vein (39.3%), but insignificant in the iliac vein and inferior vena cava (IVC). Average post contrast-to-VNE HU differences were significant (P < 0.05) in the: RA -135.3 (SD 121.8), aorta -114.1 (SD 48.5), iliac artery -104.6 (SD 53.7), kidney -30.3 (SD 34.9), spleen -9.2 (SD 8.8), and portal vein -7.7 (SD 13.2). Average VNE-to-RNE HU differences were significant in all organs but the prostate and subcutaneous fat: aorta 38.0 (SD 9.3), RA 37.8 (SD 16.1), portal vein 21.8 (SD 12.0), IVC 12.2 (SD 11.6), muscle 3.3 (SD 4.9), liver 5.7 (SD 6.4), spleen 22.3 (SD 9.8), kidney 40.5 (SD 6.8), and adrenal 20.7 (SD 13.5). On VNE images, 196/213 calcifications (92%) and 5/6 renal stones (84%) were visualized. Lytic-like artifacts in the vertebral bodies were seen in all studies. Iodine deletion in VNE images is most significant in arteries, and less significant in solid organs and veins. Most vascular and intra-abdominal organ calcifications are preserved.

Effect of Low Tube Voltage on Image Quality, Radiation Dose, and Low-Contrast Detectability at Abdominal Multidetector CT: Phantom Study

Purpose. To investigate the effect of low tube voltage (80 kV) on image quality, radiation dose, and low-contrast detectability (LCD) at abdominal computed tomography (CT). Materials and Methods. A phantom containing low-contrast objects was scanned with a CT scanner at 80 and 120 kV, with tube current-time product settings at 150–650 mAs. The differences between image noise, contrast-to-noise ratio (CNR), and scores of LCD obtained with 80 kV at 150–650 mAs and those obtained with 120 kV at 300 mAs were compared respectively. Results. The image noise substantially increased with low tube voltage. However, with identical dose, use of 80 kV resulted in higher CNR compared with CNR at 120 kV. There were no statistically significant difference in CNR and scores of LCD between 120 kV at 300 mAs and 80 kV at 550–650 mAs (P > 0.05). The relative dose delivered at 80 kV ranged from 58% at 550 mAs to 68% at 650 mAs. Conclusion. With a reduction of the tube voltage from 120 kV to 80 kV at abdominal CT, the radiation dose can be reduced by 32% to 42% without degradation of CNR and LCD.

Multidetector CT evaluation of potential right lobe living donors for liver transplantation

IntroductionLiving donor liver transplantation is increasingly being used to help compensate for the increasing shortage of cadaveric liver grafts. However, the extreme variability of the hepatic vascular systems can impede this surgical procedure. Aim of the workThe aim of the study was to demonstrate the role of multidetector CT (MDCT) in evaluation of potential right lobe living donors for liver transplantation. MethodsThe study included twenty-five liver donors in pre-operative assessment before liver transplantation. Triphasic abdominal MDCT. Post-processing techniques including multiplanner reformation (MPR), maximum intensity projection (MIP) and volume rendering (VR). ResultsTwenty donors had Michels type I variant, one donor with type Michels type II, while the remaining four had Michels type III. Sixteen donors had dominant right hepatic vein, five had late confluence of the middle hepatic vein; while remaining four donors had dominant middle hepatic vein. Twenty donors had type A portal vein branching, while the remaining five had type B portal vein branching. The percentage of right hepatic lobe for the whole liver volume ranging from 40% to 55%. ConclusionMultidetector CT provides important information in evaluation of potential living donors for liver transplantation.

Iterative Reconstruction Algorithm for Abdominal Multidetector CT at Different Tube Voltages: Assessment of Diagnostic Accuracy, Image Quality, and Radiation Dose in a Phantom Study

To assess the diagnostic accuracy, image quality, and radiation dose of an iterative reconstruction algorithm compared with a filtered back projection (FBP) algorithm for abdominal computed tomography (CT) at different tube voltages. A custom liver phantom with 45 simulated hypovascular liver tumors (diameters of 5, 10, and 15 mm; tumor-to-liver contrast of 10, 25, and 50 HU) was placed in a cylindrical water container that mimicked an intermediate-sized patient. The phantom was scanned at 120, 100, and 80 kVp. The CT data sets were reconstructed with FBP and iterative reconstruction. The image noise was measured, and the contrast-to-noise ratio (CNR) of the tumors was calculated. The radiation dose was assessed with the volume CT dose index. Tumor detection was independently performed by three radiologists. Statistical analysis included analysis of variance. Compared with the FBP data set at 120 kVp, the iterative reconstruction data set collected at 100 kVp demonstrated significantly lower mean image noise (20.9 and 16.7 HU, respectively; P < .001) and greater mean CNRs for the simulated tumors (P < .001). The iterative reconstruction data set collected at 120 kVp yielded the highest sensitivity for tumor detection, while the FBP data set at 80 kVp yielded the lowest. The sensitivity for the iterative reconstruction data set at 100 kVp was comparable with that for the FBP data set at 120 kVp (79.3% and 74.9%, respectively; P > .99). The volume CT dose index decreased by 39.8% between the 120-kVp protocol and the 100-kVp protocol and by 70.3% between the 120-kVp protocol and the 80-kVp protocol. Results of this phantom study suggest that a 100-kVp abdominal CT protocol with an iterative reconstruction algorithm for simulated intermediate-sized patients increases the image quality and maintains the diagnostic accuracy at a reduced radiation dose when compared with a 120-kVp protocol with an FBP algorithm.

Assessment of the morpho-densitometric parameters of the lumbar pedicles in osteoporotic and control women undergoing routine abdominal MDCT examinations

In transpedicular surgical operations, the pedicle should be safely penetrated. In this study, we hypothesize that morpho-densitometric data describing the physical status of the pedicle isthmus in osteoporotic versus control postmenopausal women may be generated using high-resolution three-dimensional images obtained from routine abdominal multidetector computed tomography (MDCT) scans. Thus, 32 osteoporotic and 38 postmenopausal control women had a routine abdominal scan using a 16-row CT scanner. Images of the pedicle isthmus of the L2-L4 vertebrae were generated at the plane that was vertical to the pedicle axis. Several indices were calculated based on the measurements of outer and inner dimension of the pedicle isthmus, pedicle isthmus area, and pedicle isthmus endosteal area. The mean Hounsfield unit number within the isthmus endosteal area (HU(IEA)) and the trabecular portion of the vertebral body (HU(VERT)) were measured. All subjects had a dual X-ray absorptiometry scan (DXA) in the lumbar spine. Most of the indices calculated showed statistically significant differences between osteoporotic and control women. HU(IEA) was significantly correlated to T-score (r=0.580, P<0.0001). HU(IEA) showed the best discriminatory ability between the two groups (area under ROC curve, 0.840). Routine abdominal MDCT can be used to assess the morpho-densitometric characteristics of the lumbar pedicle isthmus and differentiate osteoporotic from control postmenopausal women.

Abdominal multi-detector row CT: Effectiveness of determining contrast medium dose on basis of body surface area

To investigate the validity of determining the contrast medium dose based on body surface area (BSA) for the abdominal contrast-enhanced multi-detector row CT comparing with determining based on body weight (BW). Institutional review committee approval was obtained. In this retrospective study, 191 patients those underwent abdominal contrast-enhanced multi-detector row CT were enrolled. All patients received 96 mL of 320 mg I/mL contrast medium at the rate of 3.2 mL. The iodine dose required to enhance 1 HU of the aorta at the arterial phase and that of liver parenchyma at portal venous phase per BSA were calculated (EUBSA) and evaluated the relationship with BSA. Those per BW were also calculated (EUBW) and evaluated. Estimated enhancement values (EEVs) of the aorta and liver parenchyma with two protocols for dose decision based on BSA and BW were calculated and patient-to-patient variability was compared between two protocols using the Levene test. The mean of EUBSA and EUBW were 0.0621 g I/m2/HU and 0.00178 g I/kg/HU for the aorta, and 0.342 g I/m2/HU and 0.00978 g I/kg/HU for the liver parenchyma, respectively. In the aortic enhancement, EUBSA was almost constant regardless of BSA, and the mean absolute deviation of the EEV with the BSA protocol was significantly lower than that with the BW protocol (P<.001), although there was no significant difference between two protocols in the hepatic parenchymal enhancement (P=.92). For the aortic enhancement, determining the contrast medium dose based on BSA was considered to improve patient-to-patient enhancement variability.

The in vivo relationship between cross-sectional area and CT dose index in abdominalmultidetector CT with automatic exposure control

The relationship between patient cross-sectional area and both volume CT dose index(CTDI) and dose length product was explored for abdominal CT in vivo, using a16 multidetector row CT (MDCT) scanner with automatic exposure control.During a year-long retrospective survey of patients with MDCT for symptoms ofabdominal sepsis, cross-sectional areas were estimated using customised ellipses atthe level of the middle of vertebra L3. The relationship between cross-sectionalarea and the exposure parameters was explored. Scans were performed usinga LightSpeed 16 (GE Healthcare Medical Systems, Milwaukee, WI) operatedwith tube current modulation. From a survey of 94 patients it was found thatthe CTDI increased with the increase in patient cross-sectional area. Therelationship was logarithmic rather than linear, with a least-squares fit to the data(R2 = 0.80). For abdominal CT the cross-sectional area gave a measure of patient size based on theregion of the body to be exposed. Exposure parameters increased with increasingcross-sectional area and the greater radiation exposure of larger patients was partly aconsequence of their size. Given increasing obesity levels we believe that cross-sectionalarea and scan length should be added to future dose surveys, allowing patientsize to be considered as a factor of relevance when examining population doses.

Comparison of Conventional Abdominal CT with MR-Enterography in Patients with Active Crohn's Disease and Acute Abdominal Pain

Patients with known Crohn's disease (CD) and an acute onset of severe abdominal pain attending an emergency room frequently undergo contrast-enhanced emergency computed tomography (CT) for complication assessment. To assess small bowel changes, an additional dedicated imaging procedure such as magnetic resonance enterography (MRE) is regularly performed. Therefore, these patients undergo two imaging procedures, although the clinical and diagnostic value of such an approach is not known. In a retrospective study, we compared the diagnostic value of a conventional abdominal CT with a dedicated small bowel MRE to assess bowel wall changes as well as typical complications in patients with advanced CD. We retrospectively evaluated 53 patients with CD having a conventional abdominal multidetector-CT (MD-CT) and MRE within 2 days. Image quality and bowel inflammation was analyzed for each bowel segment. Lymph nodes, abscesses, and fistulas were evaluated. For small bowel and colon assessment, there was no significant difference for image quality between CT and MRE. Inflammation diagnosis was not significantly different between CT (69.4%) and MRE (71.4%). Colonic inflammation was diagnosed in 30.2% based on CT and 14.3% based on MRE. The difference for the detection of lymph nodes was significant (CT 49; MRE 27), whereas the differences between fistula (CT 25, MRE 27) or abscesses (CT and MRE 32) detection were not significant. In patients with known advanced CD with acute abdominal pain conventional abdominal MD-CT, which is frequently performed as an emergency imaging procedure, is sufficient for bowel wall assessment. Based on our data, additional dedicated small bowel imaging such as MRE seems not to be necessary.

Association between single-slice measurements of visceral and abdominal subcutaneous adipose tissue with volumetric measurements: the Framingham Heart Study

Volumetric visceral abdominal adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAT) as measured by computed tomography (CT) are associated with metabolic risk factors. We sought to identify the correlations of VAT and SAT between area-based measures at different anatomic locations with volumetric measurements to identify the optimal anatomic site, and to relate measurements at this site with metabolic risk factors. We measured SAT and VAT volumes across the total imaging volume, whereas we measured SAT and VAT area at seven predefined anatomic landmarks in 200 participants from the Framingham Heart Study (mean age 54 years, 50% women) who underwent abdominal multi-detector CT. Correlation coefficients were used to assess the association between area measurements and volumes as well as metabolic risk factors stratified by gender. Area-based measurements of SAT and VAT obtained at all anatomic landmarks were strongly associated with SAT and VAT volumes (all r>0.93, P<0.0001 and r>0.87, P<0.0001, for women and men; respectively). Consistently, area-based measurements of SAT and VAT obtained at L(3/4) were most strongly associated with volumetric measured VAT and SAT independent of age (both r=0.99 in men, r=0.96 for SAT and r=0.99 for VAT in women, all P-value <0.0001) and were similarly correlated with risk factors compared with SAT and VAT volumes (all P<0.05 for fasting plasma glucose, triglycerides, high-density lipoprotein, systolic blood pressure). Among area-based measurements of SAT and VAT, those obtained at the level of L(3/4) were strongly associated with SAT and VAT volumes and cardio-metabolic risk factors in both men and women.

Thoracic-abdominal MDCT: A one-stop-shop procedure for diagnosis of lymphangioleiomyomatosis

A 62-year-old asymptomatic woman was referred for an abdominal multidetector CT (MDCT) scan to evaluate a renal angyomiolipoma. Upper MDCT images revealed multiple, bilateral pulmonary cystic lesion in the costo-phrenic sulci and a thin-section MDCT scan of the chest was consequently performed. Thin-section MDCT showed several thin-walled cysts uniformly distributed throughout the lung parenchyma consistent with lymphangioleiomyomatosis (LAM). This radiological approach secured a definite diagnosis of LAM, thus avoiding further invasive procedures.