64-section Computed Tomography Research Articles

Role of MDCT in diagnosis of lower limb peripheral arteries diseases Ali Basyoni Amin, Haytham Mohamed Nasser, Mohamed Shaker Ghazy Radiology departments, Ain Shams Hospitals.

Background: Lower limb peripheral arterial disease (PAD) is a common disease that affects about two hundred million peoples per year. It is the third leading cause of cardiovascular morbidity. We plan to evaluate the diagnostic performance of 64-section computed tomographic (CT) angiography in the assessment of steno-occlusive disease in patients with PAD, with conventional digital subtraction angiography (DSA) as the reference standard. Aim of study: is to compare the diagnostic accuracy of multidetector computed tomographic (MDCT) angiography in diagnosis of PAD compared to the DSA as pre-operative evaluation of lower limb peripheral arterial diseases. Patients and methods: The study included 20 patients clinically presented with symptomatic PAD from February 2018 to July 2018. The study protocol was approved, and written informed consent was obtained from all patients. The patients underwent CT angiography and subsequent DSA. For stenosis analysis (≥70% stenosis), the arterial bed was divided into 35 segments and evaluated by three readers. Inter observer agreement was determined with generalized κ statistics. Accuracy, sensitivity, specificity, was calculated. Mc Nemar test was used to prove significant differences between CT angiographic and DSA findings. Results: A total of 700 arterial segments were evaluated, with excellent agreement between readers (κ ≥ 0.928). On a segmental basis, both sensitivity and specificity for stenosis of 70% or more were at least 96% (386 of 400 segments and 290 of 300 segments, respectively), with an accuracy of 98% (686 of 7oo segments).There was no significant difference between CT angiographic and DSA findings (P = .62–.87). Conclusion: The diagnostic performance of 64-section CT angiography is excellent in patients with clinical symptoms of PAD.

Abdominal and Pelvic Trauma: Misses and Misinterpretations at Multidetector CT: Trauma/Emergency Radiology.

HomeRadioGraphicsVol. 37, No. 2 Previous RadioGraphics FundamentalsAbdominal and Pelvic Trauma: Misses and Misinterpretations at Multidetector CT: Trauma/Emergency RadiologyMichael N. Patlas , David Dreizin, Christine O. Menias, Nikki Tirada, Sanjeev Bhalla, Savvas Nicolaou, Nataly Farshait, Douglas S. KatzMichael N. Patlas , David Dreizin, Christine O. Menias, Nikki Tirada, Sanjeev Bhalla, Savvas Nicolaou, Nataly Farshait, Douglas S. KatzAuthor AffiliationsFrom the Division of Emergency/Trauma Radiology, Department of Radiology, McMaster University, Hamilton General Hospital, 237 Barton St E, Hamilton, ON, Canada L8L 2X2 (M.N.P.); Department of Diagnostic Radiology, University of Maryland Medical Center, R. Adams Cowley Shock Trauma Center, Baltimore, Md (D.D.); Department of Radiology, Mayo Clinic School of Medicine, Scottsdale, Ariz (C.O.M.); Department of Radiology, Brigham and Women’s Hospital, Brookline, Mass (N.T.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (S.B.); Division of Emergency/Trauma Radiology, Department of Radiology, University of British Columbia, Vancouver, BC, Canada (S.N.); Infection Prevention and Control, Humber River Hospital, Toronto, Ont, Canada (N.F.); and Department of Radiology, Winthrop-University Hospital, Mineola, NY (D.S.K.).Address correspondence to M.N.P. (e-mail: [email protected]).Michael N. Patlas David DreizinChristine O. MeniasNikki TiradaSanjeev BhallaSavvas NicolaouNataly FarshaitDouglas S. KatzPublished Online:Mar 13 2017https://doi.org/10.1148/rg.2017160067MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractBeing mindful of potential diagnostic pitfalls in trauma imaging; having a thorough, efficient, and informed search strategy; and developing a working knowledge of commonly missed traumatic injuries can help radiologists improve the care of patients with abdominopelvic trauma.Suggested ReadingsChernyak V, Patlas MN, Menias CO, et al. Traumatic and non-traumatic adrenal emergencies. Emerg Radiol 2015;22(6):697–704. Crossref, Medline, Google ScholarDreizin D, Munera F. Blunt polytrauma: evaluation with 64-section whole-body CT angiography. RadioGraphics 2012;32(3):609–631. Link, Google ScholarLubner M, Menias C, Rucker C, et al. Blood in the belly: CT findings of hemoperitoneum. RadioGraphics 2007;27(1):109–125. Link, Google ScholarArticle HistoryReceived: Mar 21 2016Revision requested: July 11 2016Revision received: July 18 2016Accepted: Aug 8 2016Published online: Mar 13 2017Published in print: Mar 2017 FiguresReferencesRelatedDetailsCited ByRadiopaedia.orgLizSilverstone2023CT Imaging and Management of Blunt Splenic Trauma: Lessons for Today and TomorrowMichael N. Patlas, 2 February 2021 | Radiology, Vol. 299, No. 1Invited Commentary: Imaging and Management of Pancreatic TraumaMichael N. Patlas, 7 January 2021 | RadioGraphics, Vol. 41, No. 1Radiology and A Radiologist: A Keystone in the Turmoil of Trauma SettingKhadijaHussain, DeepakVerma, AmenaFiroz, Karez SNamiq, MahamRaza, MuhammadHaris, ManelBouchama, SafeeraKhan2021 | CureusImaging Evaluation of Abdominopelvic Gunshot TraumaFaezeh Sodagari, Douglas S. Katz, Christine O. Menias, Mariam Moshiri, John S. Pellerito, Adel Mustafa, Margarita V. Revzin, 1 October 2020 | RadioGraphics, Vol. 40, No. 6Errors in ImagingHarisChrysikopoulos2020Imaging of blunt bowel and mesenteric injuries: Current statusMostafaAlabousi, Vincent M.Mellnick, RayehKashef Al-Ghetaa, Michael N.Patlas2020 | European Journal of Radiology, Vol. 125Changes in Approach to Solid Organ Injury: What the Radiologist Needs to KnowSiobhán B.O’Neill, SairaHamid, SavvasNicolaou, Sadia R.Qamar2020 | Canadian Association of Radiologists Journal, Vol. 71, No. 3Errors in Emergency and Trauma RadiologyKateHames, Michael N.Patlas, Vincent M.Mellnick, Douglas S.Katz2019Errors in Emergency and Trauma RadiologyGabrieleMasselli, MartinaDerme2019Diagnostic Imaging in Polytrauma PatientsStefanoGiannecchini, ValentinaCaturano, CarmeloRende, ViolaValentini, MargheritaTrinci, VittorioMiele2018Multi-modality imaging of the leaking ureter: why does detection of traumatic and iatrogenic ureteral injuries remain a challenge?AbdullahAlabousi, Michael N.Patlas, Christine O.Menias, DavidDreizin, SanjeevBhalla, ManHon, AndresO’Brien, Douglas S.Katz2017 | Emergency Radiology, Vol. 24, No. 4Accompanying This ArticleAbdominal and Pelvic Trauma: Misses and Misinterpretations at Multidetector CTMay 30 2018Default Digital Object SeriesRecommended Articles CT of Penetrating Abdominopelvic TraumaRadioGraphics2021Volume: 41Issue: 4pp. 1064-1081Imaging Evaluation of Abdominopelvic Gunshot TraumaRadioGraphics2020Volume: 40Issue: 6pp. 1766-1788Invited Commentary: Key Concepts of CT for Penetrating Abdominopelvic InjuriesRadioGraphics2021Volume: 41Issue: 4pp. E119-E120Multidetector CT Findings in the Abdomen and Pelvis after Damage Control Surgery for Acute Traumatic InjuriesRadioGraphics2019Volume: 39Issue: 4pp. 1183-1202Imaging Evaluation of Tracheobronchial InjuriesRadioGraphics2020Volume: 40Issue: 2pp. 515-528See More RSNA Education Exhibits Traumatic Diaphragm Rupture: A Pictorial ReviewDigital Posters2020Trauma Meets the Urinary Tract: What the Surgeions Needs to KnowDigital Posters2020Current State of Affairs in Trauma Body Imaging: Computed Tomography (CT) ProtocolingDigital Posters2020 RSNA Case Collection Traumatic Pseudoaneurysm RSNA Case Collection2021Left Hemidiaphragmatic Rupture RSNA Case Collection2021Traumatic Diaphragmatic RuptureRSNA Case Collection2020 Vol. 37, No. 2 Slide PresentationSupplemental MaterialMetrics Altmetric Score PDF download

Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Experimental Validation.

Purpose To assess the ability of fast-kilovolt-peak switching dual-energy computed tomography (CT) by using the multimaterial decomposition (MMD) algorithm to quantify liver fat. Materials and Methods Fifteen syringes that contained various proportions of swine liver obtained from an abattoir, lard in food products, and iron (saccharated ferric oxide) were prepared. Approval of this study by the animal care and use committee was not required. Solid cylindrical phantoms that consisted of a polyurethane epoxy resin 20 and 30 cm in diameter that held the syringes were scanned with dual- and single-energy 64-section multidetector CT. CT attenuation on single-energy CT images (in Hounsfield units) and MMD-derived fat volume fraction (FVF; dual-energy CT FVF) were obtained for each syringe, as were magnetic resonance (MR) spectroscopy measurements by using a 1.5-T imager (fat fraction [FF] of MR spectroscopy). Reference values of FVF (FVFref) were determined by using the Soxhlet method. Iron concentrations were determined by inductively coupled plasma optical emission spectroscopy and divided into three ranges (0 mg per 100 g, 48.1-55.9 mg per 100 g, and 92.6-103.0 mg per 100 g). Statistical analysis included Spearman rank correlation and analysis of covariance. Results Both dual-energy CT FVF (ρ = 0.97; P < .001) and CT attenuation on single-energy CT images (ρ = -0.97; P < .001) correlated significantly with FVFref for phantoms without iron. Phantom size had a significant effect on dual-energy CT FVF after controlling for FVFref (P < .001). The regression slopes for CT attenuation on single-energy CT images in 20- and 30-cm-diameter phantoms differed significantly (P = .015). In sections with higher iron concentrations, the linear coefficients of dual-energy CT FVF decreased and those of MR spectroscopy FF increased (P < .001). Conclusion Dual-energy CT FVF allows for direct quantification of fat content in units of volume percent. Dual-energy CT FVF was larger in 30-cm than in 20-cm phantoms, though the effect of object size on fat estimation was less than that of CT attenuation on single-energy CT images. In the presence of iron, dual-energy CT FVF led to underestimateion of FVFref to a lesser degree than FF of MR spectroscopy led to overestimation of FVFref. © RSNA, 2016 Online supplemental material is available for this article.

Automatic radiation dose monitoring for CT of trauma patients with different protocols: feasibility and accuracy

To demonstrate the feasibility and accuracy of automatic radiation dose monitoring software for computed tomography (CT) of trauma patients in a clinical setting over time, and to evaluate the potential of radiation dose reduction using iterative reconstruction (IR). In a time period of 18 months, data from 378 consecutive thoraco-abdominal CT examinations of trauma patients were extracted using automatic radiation dose monitoring software, and patients were split into three cohorts: cohort 1, 64-section CT with filtered back projection, 200mAs tube current-time product; cohort 2, 128-section CT with IR and identical imaging protocol; cohort 3, 128-section CT with IR, 150mAs tube current-time product. Radiation dose parameters from the software were compared with the individual patient protocols. Image noise was measured and image quality was semi-quantitatively determined. Automatic extraction of radiation dose metrics was feasible and accurate in all (100%) patients. All CT examinations were of diagnostic quality. There were no differences between cohorts 1 and 2 regarding volume CT dose index (CTDIvol; p=0.62), dose-length product (DLP), and effective dose (ED, both p=0.95), while noise was significantly lower (chest and abdomen, both -38%, p<0.017). Compared to cohort 1, CTDIvol, DLP, and ED in cohort 3 were significantly lower (all -25%, p<0.017), similar to the noise in the chest (-32%) and abdomen (-27%, both p<0.017). Compared to cohort 2, CTDIvol (-28%), DLP, and ED (both -26%) in cohort 3 was significantly lower (all, p<0.017), while noise in the chest (+9%) and abdomen (+18%) was significantly higher (all, p<0.017). Automatic radiation dose monitoring software is feasible and accurate, and can be implemented in a clinical setting for evaluating the effects of lowering radiation doses of CT protocols over time.

Determination of Single-Kidney Glomerular Filtration Rate in Human Subjects by Using CT.

To test the hypothesis that computed tomography (CT)-derived measurements of single-kidney glomerular filtration rate (GFR) obtained in human subjects with 64-section CT agree with those obtained with iothalamate clearance, a rigorous reference standard. The institutional review board approved this HIPAA-compliant study, and written informed consent was obtained. Ninety-six patients (age range, 51-73 years; 46 men, 50 women) with essential (n = 56) or renovascular (n = 40) hypertension were prospectively studied in controlled conditions (involving sodium intake and renin-angiotensin blockade). Single-kidney perfusion, volume, and GFR were measured by using multidetector CT time-attenuation curves and were compared with GFR measured by using iothalamate clearance, as assigned to the right and left kidney according to relative volumes. The reproducibility of CT GFR over a 3-month period (n = 21) was assessed in patients with renal artery stenosis who were undergoing stable medical treatment. Statistical analysis included the t test, Wilcoxon signed rank test, linear regression, and Bland-Altman analysis. CT GFR values were similar to those of iothalamate clearance (mean ± standard deviation, 38.2 mL/min ± 18 vs 41.6 mL/min ± 17; P = .062). Stenotic kidney CT GFR in patients with renal artery stenosis was lower than contralateral kidney GFR or essential hypertension single-kidney GFR (mean, 23.1 mL/min ± 13 vs 36.9 mL/min ± 17 [P = .0008] and 45.2 mL/min ± 16 [P = .019], respectively), as was iothalamate clearance (mean, 26.9 mL/min ± 14 vs 38.5 mL/min ± 15 [P = .0004] and 49.0 mL/min ± 14 [P = .001], respectively). CT GFR correlated well with iothalamate GFR (linear regression, CT GFR = 0.88*iothalamate GFR, r(2) = 0.89, P < .0001), and Bland-Altman analysis was used to confirm the agreement. CT GFR was also moderately reproducible in medically treated patients with renal artery stenosis (concordance coefficient correlation, 0.835) but was unaffected by revascularization (mean, 25.3 mL/min ± 15.2 vs 30.3 mL/min ± 18.5; P = .097). CT assessments of single-kidney GFR are reproducible and agree well with a reference standard. CT can be useful to obtain minimally invasive estimates of bilateral single-kidney function in human subjects.

Bone remodeling after MR imaging-guided high-intensity focused ultrasound ablation: evaluation with MR imaging, CT, Na(18)F-PET, and histopathologic examination in a swine model.

To serially monitor bone remodeling in the swine femur after magnetic resonance (MR) imaging-guided high-intensity focused ultrasound (HIFU) ablation with MR imaging, computed tomography (CT), sodium fluorine 18 (Na(18)F)-positron emission tomography (PET), and histopathologic examination, as a function of sonication energy. Experimental procedures received approval from the local institutional animal care and use committee. MR imaging-guided HIFU was used to create distal and proximal ablations in the right femurs of eight pigs. The energy used at the distal target was higher (mean, 419 J; range, 390-440 J) than that used at the proximal target (mean, 324 J; range, 300-360 J). Imaging was performed before and after ablation with 3.0-T MR imaging and 64-section CT. Animals were reevaluated at 3 and 6 weeks with MR imaging (n = 8), CT (n = 8), Na(18)F-PET (n = 4), and histopathologic examination (n = 4). Three-dimensional ablation lengths were measured on contrast material-enhanced MR images, and bone remodeling in the cortex was measured on CT images. Ablation sizes at MR imaging 3 and 6 weeks after MR imaging-guided HIFU ablation were similar between proximal (low-energy) and distal (high-energy) lesions (average, 8.7 × 21.9 × 16.4 mm). However, distal ablation lesions (n = 8) demonstrated evidence of subperiosteal new bone formation at CT, with a subtle focus of new ossification at 3 weeks and a larger focus of ossification at 6 weeks. New bone formation was associated with increased uptake at Na(18)F-PET in three of four animals; this was confirmed at histopathologic examination in four of four animals. MR imaging-guided HIFU ablation of bone may result in progressive remodeling, with both subcortical necrosis and subperiosteal new bone formation. This may be related to the use of high energies. MR imaging, CT, and PET are suitable noninvasive techniques to monitor bone remodeling after MR imaging-guided HIFU ablation.

Dual-source CT versus single-source 64-section CT angiography for coronary artery disease: A meta-analysis

To perform a meta-analysis to compare the diagnostic performance of single-source 64-section computed tomography (CT) versus dual-source CT angiography for diagnosis of coronary artery disease (CAD). The Cochrane Library, MEDLINE, and EMBASE were searched for relevant original papers. Inclusion criteria were (1) significant CAD defined as ≥50% reduction in luminal diameter by invasive coronary angiography as reference standard; (2) single-source 64-section CT or dual-source CT was used; (3) results were reported in absolute numbers of true-positive, false-positive, true-negative, and false-negative results or sufficiently detailed data for deriving these numbers were presented. A random-effects model was used for the meta-analysis. Fifty-one papers including 3966 patients who underwent single-source 64-section CT and 2047 patients who underwent dual-source CT at a per-patient level were pooled. The diagnostic values of single-source 64-section CT versus dual-source CT were 97% versus 97% for sensitivity (p = 0.386), 78% versus 86% for specificity (p < 0.001), 90% versus 85% for positive predictive value (PPV; p < 0.001), 93% versus 97% for negative predictive value (NPV; p = 0.001), 6.8 versus 6.5 for positive likelihood ratio (p = 0.018), 0.04 versus 0.04 for negative likelihood ratio (p = 0.625), and 191.59 versus 207.37 for diagnostic odds ratio (p = 0.043), respectively. Dual-source CT and single-source 64-section CT have similar negative likelihood ratios and, therefore, there was no significant difference in their utility to rule out CAD in intermediate-risk patients. However, compared to single-source 64-section CT, dual-source CT has significantly higher specificity, so that CT-based decisions for subsequent coronary catheter angiography are more accurate.

Feasibility of Single-Source Dual-Energy Computed Tomography for Urinary Stone Characterization and Value of Iterative Reconstructions

The purposes of this study were to demonstrate the feasibility and accuracy of single-source dual-energy (DE) computed tomography (CT) with sequential data acquisition and a coregistration motion correction algorithm for urinary stone characterization and to evaluate the value of iterative reconstructions (IRs) in DE imaging. Thirty-five urinary stones were placed in cylindrical phantoms with diameters of 30 and 40 cm. The phantoms were scanned on a 64-section CT machine with a single-source DE protocol consisting of 2 sequential acquisitions at 80 and 140 kilovolt (peak). The phantom was moved between the 80- and 140-kilovolt (peak) scans. Images were reconstructed with weighted filtered back projection (FBP) and with IR, and data were coregistered. Two independent and blinded readers assessed data sets for stone detection, overall image quality, and visibility of stones. Image noise and Hounsfield unit values of the stones were measured, and the DE index was calculated. In addition, the data sets were analyzed on color-coded images using the standard postprocessing software for differentiating uric acid- (UA) from non-UA-containing stones. The motion correction algorithm achieved a good coregistration of the 2 scans with different energy levels. Both readers detected all stones on all data sets with both reconstruction types. The overall image quality was rated significantly higher in IR images in the 40-cm phantom as compared with that in FBP images (P < 0.05), whereas no significant difference was found for the 30-cm phantom. Visibility of stones was rated significantly higher for both the 30- and 40-cm phantoms on IR as compared with that on FBP images, an effect that was pronounced for UA stones (P < 0.05). Noise was significantly reduced by up to 31% in the 40-cm phantom when using IR as compared with FBP (P < 0.001). The DE index was similar in the FBP and IR data sets for the 30- (P = 0.116) and 40-cm phantoms (P = 0.544), being significantly different between UA-containing stones, cystine, and struvite stones as well as stones of other compositions (P < 0.001). The postprocessing software classified all stones correctly as UA- or non-UA-containing stones on color-coded images. In the 40-cm phantom, false-positively colored voxels were found in the FBP data sets, which were not seen when using IR instead. Our study indicates that single-source dual-energy CT with sequential acquisitions at different energy levels and a coregistration motion correction algorithm is feasible and accurate for characterizing urinary stone composition on the basis of phantom evaluation. As compared with reconstructions with FBP, the use of IR in dual-energy CT reduces noise, improves overall image quality and visibility of stones particularly in large phantoms, and helps to avoid false classifications of urinary stones.

Case 200: Gastric Enterochromaffinlike Cell Tumors in a Patient with Type 1 Multiple Endocrine Neoplasia

History A 55-year-old man presented with chronic epigastric pain lasting for about 1 year and without fever or vomiting. The abdomen was soft and tender at physical examination. Laboratory tests revealed unremarkable liver function, normal hemoglobin level, and normal amylase level. White blood cell count was normal, and there was no inflammatory syndrome. The patient's medical history included pancreatic gastrinoma resected by means of left pancreatectomy 31 years before, hyperparathyroidism treated with subtotal parathyroidectomy 24 years before, and a slowly growing lung mass known for 9 years. Esophagogastroduodenoscopy was performed because of a suspected gastroduodenal ulcer. The results showed numerous small (<10 mm) gastric and duodenal ulcers and multiple 10-15-mm polypoid gastric masses. Contrast material-enhanced dual-phase multidetector row computed tomography (CT) of the chest and abdomen was performed with a 64-section CT scanner (LightSpeed VCT; GE Healthcare, Milwaukee, Wis). Technical parameters for CT were as follows: pitch, 0.98; section thickness and reconstruction interval, 1.25 mm; 120 kVp; and variable milliamperage determined by x-, y-, and z-axis dose modulation. After an unenhanced abdominal scan, iobitridol, a nonionic iodinated contrast agent containing 350 mg of iodine per milliliter (Xenetix 350; Guerbet, Aulnay-sousbois, France), was administered intravenously through a 16-18-gauge catheter. A 120-mL dose of the contrast agent was injected via an antecubital vein at a rate of 4 mL/sec. No oral contrast medium was administered. After preliminary unenhanced abdominal scanning, arterial and portal venous phase acquisitions were obtained 45 and 80 seconds after initiation of contrast medium injection.

Increased Unenhanced Bowel-Wall Attenuation at Multidetector CT Is Highly Specific of Ischemia Complicating Small-Bowel Obstruction

To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard. The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30-100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ(2) tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement. In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308). Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent.

Increased Unenhanced Bowel-Wall Attenuation at Multidetector CT Is Highly Specific of Ischemia Complicating Small-Bowel Obstruction

Purpose To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard. Materials and Methods The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30–100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ2 tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement. Results In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308). Conclusion Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent. © RSNA, 2013

Model-based Iterative Reconstruction for Multi–Detector Row CT Assessment of the Adamkiewicz Artery

To determine if model-based iterative reconstruction (MBIR) can improve visualization of the Adamkiewicz artery on multi-detector row computed tomographic (CT) images compared with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP). This retrospective study was approved by the institutional review board, and written informed consent for the CT examination was obtained. Thirty-three patients underwent contrast material-enhanced 64-section multi-detector row CT for assessment of aortic aneurysm or dissection. Helical data were reconstructed by using FBP, ASIR, and MBIR. The signal-to-noise ratio of the aorta and contrast-to-noise ratio of the anterior spinal artery relative to the spinal cord were measured on multiplanar reformatted images. Visualization of the Adamkiewicz artery and its continuity with the intercostal or lumbar artery were evaluated by using a four-point scale. All image analyses were performed by two blinded, independent observers. The one-way analysis of variance and the Wilcoxon signed-rank test were used for statistical analysis. MBIR showed significantly better signal-to-noise and contrast-to-noise ratios than did ASIR and FBP (P < .05 for all comparisons) with good interobserver agreement (intraclass correlation coefficient of 0.93 for signal-to-noise ratio and 0.75 for contrast-to-noise ratio). The visualization score of the Adamkiewicz artery was also significantly better when MBIR was used (3.4 ± 0.8 and 3.6 ± 0.7 for observers A and B, respectively) than when ASIR (2.7 ± 1.1 and 3.0 ± 1.0, respectively) or FBP (2.5 ± 1.2 and 3.1 ± 0.9, respectively) was used. Use of the MBIR algorithm led to improved multi-detector row CT visualization of the Adamkiewicz artery when compared with the use of ASIR and FBP.

Image quality and radiation exposure in CT of the pancreas: 320-MDCT with and without adaptive iterative dose reduction versus 64-MDCT

To compare the image quality and radiation exposure in computed tomography (CT) of the pancreas acquired using 320-multidetector (MD)CT versus 64-MDCT and to demonstrate the effects of adaptive iterative dose reduction (AIDR) on 320-MDCT. One hundred and fifty patients were randomized into three groups including 320-section volume imaging using AIDR (group A), 320-slice volume scan without AIDR (group B), and 64-section helical imaging without AIDR (group C). Transaxial arterial, pancreatic phase, and volume-rendered CT angiographic images were reconstructed. CT radiodensity of the abdominal aorta, pancreas, signal-to-noise ratios (SNR), dose-length products (DLPs; mGycm), and image quality were measured. No significant difference in CT radiodensity of the abdominal aorta or pancreas was noted between groups. Mean DLPs were 600.9±145.8, 681.6±97.5, and 1231.5±271.4 in groups A, B, and C, respectively. The DLP was reduced by 51% in group A and 45% in group B compared to group C (p<0.001). SNRs of the pancreas during the pancreatic phase were comparable between groups A and C, but were significantly lower in group B (p<0.001). Image quality, including the depiction of some small arterial branches on the arterial and CT angiographic images and the main pancreatic duct on the pancreatic-phase images, were significantly lower in group B than in groups A and C (p=0.008-0.038). Radiation dose can be markedly reduced for contrast-enhanced CT imaging of the pancreas without compromising image quality using a 320-MDCT with AIDR, compared with 64-section helical CT.

Case 200

Case 200

Pitfalls and mimickers at 64-section helical CT that cause negative appendectomy: an analysis from 1057 appendectomies

PurposeTo determine the rate of negative appendectomy and clarify the causes of negative appendectomy in patients with clinically suspected acute appendicitis who had surgery after 64-section helical computed tomography (CT). Material and MethodsA retrospective analysis of 1057 patients who had appendectomy after 64-section helical CT was performed to determine the rate of negative appendectomy. The 64-section helical CT examinations obtained with submillimeter and isotropic voxels in the patients with negative appendectomy were analyzed by two readers and compared to clinical, operative and histopathological reports, discharge summaries and original radiology reports. ResultsThe negative appendectomy rate was 1.7% (18/1057). Appendix enlargement (>6 mm) and fat stranding were present in 17 (17/18; 94%) and 6 patients (6/18; 33%), respectively. In 13 patients (13/18; 72%) 64-section helical CT findings were consistent with acute appendicitis. Interpretive errors in original imaging reports were identified in five patients (5/18; 28%). ConclusionThe preoperative use of 64-section helical CT results in a very low rate of negative appendectomy. Patients with negative appendectomy have 64-section helical CT findings consistent with a diagnosis of acute appendicitis in the majority of cases. Interpretive errors are less frequent.

Penetrating Diaphragmatic Injury: Accuracy of 64-Section Multidetector CT with Trajectography

To (a) determine the diagnostic performance of 64-section multidetector computed tomography (CT) trajectography for penetrating diaphragmatic injury (PDI), (b) determine the diagnostic performance of classic signs of diaphragmatic injury at 64-section multidetector CT, and (c) compare the performance of these signs with that of trajectography. This HIPAA-compliant retrospective study had institutional review board approval, with a waiver of the informed consent requirement. All patients who had experienced penetrating thoracoabdominal trauma, who had undergone preoperative 64-section multidetector CT of the chest and abdomen, and who had surgical confirmation of findings during a 2.5-year period were included in this study (25 male patients, two female patients; mean age, 32.6 years). After a training session, four trauma radiologists unaware of the surgical outcome independently reviewed all CT studies and scored the probability of PDI on a six-point scale. Collar sign, dependent viscera sign, herniation, contiguous injury on both sides of the diaphragm, discontinuous diaphragm sign, and transdiaphragmatic trajectory were evaluated for sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV). Accuracies were determined and receiver operating characteristic curves were analyzed. Sensitivities for detection of PDI by using 64-section multidetector CT with postprocessing software ranged from 73% to 100%, specificities ranged from 50% to 92%, NPVs ranged from 71% to 100%, PPVs ranged from 68% to 92%, and accuracies ranged from 70% to 89%. Discontinuous diaphragm, herniation, collar, and dependent viscera signs were highly specific (92%-100%) but nonsensitive (0%-60%). Contiguous injury was generally more sensitive (80%-93% vs 73%-100%) but less specific (50%-67% vs 83%-92%) than transdiaphragmatic trajectory when patients with multiple entry wounds were included in the analysis. Transdiaphragmatic trajectory was a much more sensitive sign of PDI than previously reported (73%-100% vs 36%), with NPVs ranging from 71% to 100% and PPVs ranging from 85% to 92%. Sixty-four-section multidetector CT trajectography facilitates the identification of transdiaphragmatic trajectory, which accurately rules in PDI when identified. Contiguous injury remains a highly sensitive sign, even when patients with multiple injuries are considered, and is useful for excluding PDI.

Revised protocol for whole-body CT for multi-trauma patients applying triphasic injection followed by a single-pass scan on a 64-MDCT

To evaluate a revised protocol for whole-body computed tomography (CT) for multi-trauma patients in an emergency department and compare it to conventional protocols. Forty-two of 82 multi-trauma patients underwent unenhanced CT examinations of the head, cervical spine, and upper abdomen, followed by an arterial-phase contrast-enhanced CT examination of the thorax and a porto-venous scan of the abdomen and pelvis (conventional protocol). The other 40 patients underwent unenhanced CT examinations of the head, cervical spine, and upper abdomen, followed by a one-step acquisition of the thorax, abdomen, and pelvis using a 64-section multidetector CT (MDCT) system following a triphasic injection (revised protocol). Contrast enhancement was measured in the ascending, descending, and abdominal aorta, common iliac arteries, inferior vena cava (IVC), liver, spleen, and kidneys. Image count, radiation dose, total acquisition time, mediastinal artefacts, and image quality of each area were reviewed. Mean enhancement values in the ascending and descending aorta were significantly greater with the conventional protocol. Enhancement of the abdominal aorta, iliac arteries, IVC, liver, spleen, and kidneys was significantly greater with the revised protocol. Mediastinal streak artefacts were present in all conventional protocol images and absent in all revised protocol images. Image quality using the revised protocol was significantly better (p<0.002). The mean effective radiation dose was significantly lower (p=0.005), and image number reduced (p<0.001). The revised triphasic injection single-pass whole-body imaging protocol was superior to the conventional protocol using 64-MDCT. It enabled better vascular and abdominal parenchymal imaging with reduction in radiation dose and image overload.

Radiation Dose Reduction at Multidetector CT with Adaptive Statistical Iterative Reconstruction for Evaluation of Urolithiasis: How Low Can We Go?

To evaluate the performance of computed tomographic (CT) examinations at 80 and 100 kV with tube current-time products of 75-150 mA and the effect of adaptive statistical iterative reconstruction (ASIR) on CT image quality in patients with urinary stone disease. In this HIPAA-compliant institutional review board-approved study, verbal consent for prospective low-dose CT and waivers of consent for retrospective review of CT scans were obtained. Between November 2010 and April 2011, 25 patients (15 men, 10 women; mean age, 35 years) with urolithiasis underwent 64-section multidetector CT with 75-150 mA and noise index of 30. Modified protocol was based on body weight (<200 lb [90 kg], 80 kV; >200 lb [90 kg], 100 kV). Images of 5-mm section thickness were reconstructed with filtered back projection (FBP) and 60% and 80% ASIR techniques, with 3-mm coronal and sagittal reformations. Two readers independently reviewed FBP and ASIR data sets for image quality (scale, 1-5), noise (scale , 1-3), and calculi (number, size, location). Confidence levels for urolithiaisis and alternate diagnoses were rated (scale, 1-3). In 13 patients, FBP CT images acquired with the reference standard departmental protocol were available for comparison. Radiation dose was compared between imaging series. Statistical analysis was performed with Wilcoxon signed rank and paired t tests. Modified-protocol FBP images showed low image quality (score, 2.5), with improvement on modified-protocol ASIR images (score, 3.4) (P=.03). All 33 stones (mean diameter, 6.1 mm; range, 2-28 mm) at modified-protocol CT were diagnosed by both readers. In 20 of 25 patients (80%), ASIR images were rated adequate for rendering other diagnoses in the abdomen (score, 2.0), as opposed to FBP images (score, 1.3). Mean radiation dose for modified-protocol CT was 1.8 mGy (1.3 mGy for patients<200 lb; 2.3 mGy for patients>200 lb) in comparison with 9.9 mGy for reference-protocol CT (P=.001). Image quality improvements with ASIR at reduced radiation dose of 1.8 mGy enabled effective evaluation of urinary calculi without substantially affecting diagnostic confidence. © RSNA, 2012.

Low-Dose Multidetector CT Angiography in the Evaluation of Infrarenal Aorta and Peripheral Arterial Occlusive Disease

To investigate the ionizing radiation dose, image quality, and diagnostic performance of computed tomographic (CT) angiography of the peripheral arteries with three different CT angiographic acquisition protocols, with use of pretreatment digital subtraction angiography (DSA) as the reference standard. The study was approved by the institutional review board and performed in agreement with the 1990 Declaration of Helsinki and subsequent amendments. Each patient provided informed consent before undergoing CT. The authors performed a prospective, single-center, randomized comparison of three different x-ray exposure CT acquisition protocols in 60 randomized patients with peripheral arterial occlusive disease referred for 64-section multidetector CT angiography of the lower limb (0.625-mm collimation, intravenous administration of 100 mL of iomeprol [400 mg iodine per milliliter] at 4 mL/sec). The acquisition protocols were performed with (a) 120 kVp and a noise index of 26 (moderate noise reduction [MNR]), referred to as the 120-kVp MNR group; (b) 80 kVp and a noise index of 26, referred to as the 80-kVp MNR group; and (c) 80 kVp and a noise index of 30 (high noise reduction [HNR]), referred to as the 80-kVp HNR group. Axial and three-dimensional (3D) images were qualitatively and quantitatively compared by using the overall F test and pairwise comparisons. The X(2) test was used to compare the three protocols in terms of diagnostic performance in patients who also underwent DSA before an interventional procedure. Significantly higher attenuation values were obtained in the vessels with the 80-kVp MNR and 80-kVp HNR acquisition protocols. No significant differences were noted in terms of image quality with either axial source images or 3D reconstructions. Likewise, no significant differences were found among the three protocols in terms of noise throughout the peripheral vasculature. Finally, no significant differences were found among the three groups with regard to diagnostic performance. Overall dose reductions of 48% and 61% were obtained for the 80-kVp MNR and 80-kVp HNR protocols, respectively. Substantial reductions of radiation dose are achievable at multidetector CT angiography of the peripheral arteries without compromising image quality and diagnostic performance if acquisition protocols are modified appropriately and used in conjunction with a contrast material containing a high concentration of iodine.

Hepatic Height on Coronal Computed Tomography Images Predicts Total Liver Volume in European Adults Without Liver Disease

Hepatic volume measurement provides useful information in a large range of clinical situations. The goal of this study was to test the hypothesis that significant correlation exists between hepatic volume calculated using three-dimensional reconstruction of computed tomography (CT) data and hepatic height calculated using coronal reformation of CT images in European adult patients without liver disease. One hundred patients (50 men, 50 women; mean age, 47 years) without hepatic disease were included. Coronal and three-dimensional images of the liver were obtained using 64-section helical CT. Correlation between hepatic height and hepatic volume was searched for using the Pearson correlation test. Regression analysis was used to compare hepatic height and hepatic volume. A strong and highly significant positive correlation was found between hepatic height and hepatic volume, with a correlation coefficient (r) of 0.767 (95%CI 0.672-0.837; r² = 0.588) (P < 0.001). The equation of the correlation line was y = 11.764x - 244 where y represents the hepatic volume in cm³ and x the hepatic height in mm. Hepatic height as obtained on coronal CT image is a simple and rapid measurement that allows predicting hepatic volume in European adult patients without liver disease.