64 MDCT in multiple trauma patients: imaging manifestations and clinical implications of active extravasation

The finding of active hemorrhage on computed tomography (CT) in trauma patients has been shown to have significant clinical implications and has been incorporated into numerous CT grading schema. As CT technology has advanced, the sensitivity for detection of active hemorrhage in the trauma population has significantly improved. Currently, with the improved spatial and temporal resolution afforded by 64 multidetector computed tomography (64 MDCT) technology, the clinical implications of the CT findings of active extravasation may need to be reconsidered. This article illustrates the various imaging manifestations of active extravasation throughout the body using 64 MDCT. Additionally, protocol issues specific to the findings of active hemorrhage using 64 MDCT are detailed, including novel interpretation techniques, which offer aid in detecting and characterizing hemorrhage. Finally, the clinical implication of active extravasation using this new technology is discussed. Although more sensitive to the detection of small hemorrhagic foci and with clinical implications highly dependent upon location, active bleeding remains as a salient finding that affects subsequent clinical management of trauma patients.     

Coronary artery bypass graft imaging with 256-slice MDCT: surgical concepts,current techniques,and interpretation

Multidetector computed tomography (MDCT) scanners with current equipment allow for a rapid and robust noninvasive assessment of coronary artery bypass graft (CABG) anatomy and patency. With both appropriate expertise in MDCT techniques and knowledge in CABG imaging interpretation, radiologists should play an important and active role in the postoperative care of patients with bypass grafts. In this pictorial essay, we review the MDCT techniques and anatomy relevant to CABG imaging, interpretation pitfalls, some basic and advanced surgical designs, as well as postoperative graft complications in patients with CABG, with clinical illustrations from our local experience.     

Role of MDCT coronary angiography in the clinical setting: economic implications

Purpose

This study evaluated the incremental value and cost-effectiveness ratio of introducing coronary angiography (CA) with multidetector computed tomography (MDCT-CA) in the diagnostic management of patients with suspected coronary artery disease (CAD) compared with the traditional diagnostic workup.

Material and methods

Five hundred and fifty consecutive patients who underwent MDCT-CA between January 2009 and June 2011 were considered. Patients with atypical chest pain and suspected obstructive CAD were directed to one of two diagnostic pathways: the traditional protocol (examination, stress test, CA) and the current protocol (examination, stress test, MDCT-CA, and CA, if necessary). The costs of each protocol and for the individual method were calculated. Based on the results, the cost-effectiveness ratio of the two diagnostic pathways was compared. A third, modified, diagnostic pathway has been proposed with its relative cost-effectiveness ratio (examination, MDCT-CA, stress test, and CA, if necessary).

Results

Stress test vs. MDCT-CA had an accuracy of 66%, a sensitivity and specificity of 21% and 87%, respectively, and a positive (PPV) and negative (NPV) predictive value of 40% and 70%, respectively. Comparison between conventional CA (CCA) and MDCT-CA showed a sensitivity and specificity of 92% and 89%, respectively, a PPV and NPV of 89%, and an accuracy of 92%. The traditional protocol has higher costs than the second protocol: 1,645 euro against 322 euro (mean), but it shows a better cost-effectiveness ratio. The new proposed protocol has lower costs, mean 261 euro, with a better costeffectiveness ratio than the traditional protocol.

Conclusions

The diagnostic protocol for patients with suspected CAD has been modified by the introduction of MDCT-CA. Our study confirms the greater diagnostic performance of MDCT-CA compared with stress test and its similar accuracy to CCA. The use of MDCT-CA to select patients for CCA has a favourable cost-effectiveness profile.     

Ulnar dimelia: imaging modalities and surgical implications

PURPOSE: To report 2patients with ulnar dimelia. METHODS: Plain radiographs (2patients), angiography (1patient), MR (2patients), CT (2patients) with 3Dreconstruction (1patient) were performed. RESULTS: Unilateral polydactyly with absence of the thumb, ulnar duplication with absence of radius were observed in both patients. Shoulder dislocation was present in one patient. Vascular anomalities were observed in one patient who underwent angiography but did not interfere with polydactyly surgical treatment and pollicisation. CT with 3D helped in delineating the elbow and shoulder bone abnormalities and thus in planning elbow osteotomies. MR was helpful in imaging muscle anatomy. CONCLUSIONS: Ulnar dimelia or "mirror hand" is a rare congenital disorder of the upper limb. Approximately 70cases have been reported, including 3 with shoulder dislocation. A multimodality imaging approach, exploring the various aspects of the malformation is mandatory to help the surgeon in order to obtain a functional and aesthetic upper limb after complex surgical procedures taking into account the various aspects of the malformation.     

Cardiac imaging including nuclear medicine, MRI, and MDCT

Nuclear cardiology has played a significant role in the diagnosis and risk stratification of patients with coronary artery disease. MRI and multidector-row CT (MDCT) has recently been introduced in the field of clinical cardiology. For the management of patients with suspected coronary artery disease, it is important to understand the advantages and disadvantages of various imaging modalities. This review discusses the current roles and problems of these imaging modalities.     

Head and neck imaging with MDCT

Multi-slice CT (MDCT) is rapidly becoming the new standard in radiological imaging. Although its advantages in cardiovascular, thoracic and abdominal imaging are evident, the extent of its usefulness for imaging the head and neck has yet to be clarified. Because of the shorter examination time motion artifacts are reduced, phonation-studies are possible. Due to the thin-slicing and nearly isotropic multiplanar reconstruction (MPR) examination in only one plane is necessary, saving both time and radiation exposure. The shorter examination requires the use of higher concentrated contrast medium (400 mg of iodine/ml). The use of such a contrast medium produces a higher degree of contrast enhancement and provides a 5-10% higher contrast between the surrounding normal and pathological tissue, but is more time critical. MPRs are easily done in any plane within seconds and enables also three-dimensional visualization, what helps in the use of minimal invasive therapy, training and teaching and provides a way of handling the hundreds of images acquired during scanning.     

Bypass graft imaging and coronary anomalies in MDCT

Coronary artery bypass graft (CABG) is used to restore the blood flow in an ischemic area of myocardium using conduits bypassing a diseased coronary artery. Until now, conventional angiography has been the recognized technique to study patients with bypass grafts. Nowadays, non-invasive methods such as multi-detector CT (MDCT) emerge as reliable imaging methods in the study of CABG. Thus, radiologists play an important role in this field, not only to define if the bypass graft is occluded or stenosed but also to report further information such as CABG technique performed, type of conduit used or pre-operative findings. This paper analyzes the most practical information that the radiologist must know in a study of CABG. Another theme which will be briefly described is the use of MDCT in coronary anomalies studies, with particular emphasis on the course of the abnormal vessel and its relation to great vessels.     

MR imaging of pituitary adenoma: CT, clinical, and surgical correlation

Twenty-five patients with suspected pituitary adenoma were evaluated prospectively with CT and MR. Nine patients underwent transsphenoidal surgery, and three of these showed a documented decrease in size of mass on bromocriptine therapy. CT was more sensitive than MR for detecting focal lesions (seven vs three) and sellar-floor erosion (12 vs six). MR was superior to CT in identifying infundibular abnormalities (seven vs six), focal abnormalities of the diaphragma sellae (10 vs seven), cavernous sinus invasion (four vs two), and optic chiasm compression (six vs zero). Thus, MR may be the procedure of choice for optimal identification and localization of macroadenoma. For patients with suspected microadenoma, however, this preliminary series indicates that CT remains the radiographic procedure of choice.     

MDCT: a new era in imaging

Multidetector row computed tomography (MDCT) is an effective imaging technology, providing rapid and non-invasive images in three dimensions. Compared with standard computed tomography (CT), MDCT allows faster data acquisition and shorter scan times, with wider coverage, high resolution and the potential for cardiac gating. Routine thin-section acquisition allows for flexible reconstruction (thick or thin slices), while dedicated software provides three-dimensional and functional data analysis. The technology has a wide range of applications, particularly in cardiovascular medicine, where CT angiography has replaced conventional angiography in many regions of the body. Motion artefacts on cardiac scans are significantly reduced, and the diagnosis of luminal obstructive disease is enhanced. For non-cardiac applications, MDCT allows imaging of extensive arterial territories with unprecedented volumetric resolution. The detection of pulmonary emboli, characterization of arterial aneurysms and presurgical mapping are all improved substantially with MDCT. Pulmonary parenchymal imaging is enhanced, including superior lung nodule detection and better airway assessments. MDCT has rendered some diagnostic techniques, such as intravenous urography, virtually obsolete. The development of MDCT continues, with promises of further improvements and enhancements.     

MR imaging of the meniscus: review, current trends, and clinical implications

MR imaging is the preferred imaging modality for evaluating the meniscus. Overall, when strict criteria are followed, it is accurate in diagnosing meniscal tears in patients who have not had prior meniscal surgery. However, an accurate interpretation requires a through knowledge of the normal meniscal anatomy, common meniscal variants, and common diagnostic pitfalls. In this article, the author emphasizes the importance of describing meniscal tears properly and discusses treatment options. Diagnosing a recurrent tear is more complicated in patients who have had prior partial meniscal resection or repair, and the use of MR arthrography in this group of patients is discussed. Recent developments in areas such as 3 T and parallel imaging offer promise for accurate meniscal evaluation with even shorter scan times.     

MDCT and 3D imaging in transient enteroenteric intussusception: clinical observations and review of the literature

OBJECTIVE: This article will review the current role of MDCT and 3D imaging in the diagnosis and management of adults with enteroenteric intussusception. CONCLUSION: Because of significant advancements in CT along with its increasing use, detection of enteroenteric intussusceptions by CT has increased. These findings are sometimes in asymptomatic patients, often transient, and without an identifiable lead point. This has complicated the management of adult patients with intussusception because not every patient with intussusception may need surgery.     

MDCT imaging of the aorta and peripheral vessels

Since its clinical introduction in 1991, volumetric CT scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. Helical CT has improved over the past 8 years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row CT (MDCT) scanners [J. Comput. Assist. Tomogr. 23 (1999) S83]. Currently capable of acquiring four channels of helical data simultaneously, MDCT scanners have achieved the greatest incremental gain in scan speed since the development of helical CT and have profound implications for clinical CT scanning. Fundamental advantages of MDCT include substantially shorter acquisition times, retrospective creation of thinner or thicker sections from the same raw data, and improved three-dimensional (3-D) rendering with diminished helical artifacts. While these features will likely be important to many applications of CT scanning, including the characterization of focal lung and liver lesions through the creation of thin sections retrospectively, the greatest impact has been on CT angiography. The implication for CT angiography is that scans can be performed approximately three-times faster than is possible with the fastest single-detector CT scanner. For example a 1.25 mm nominal thick section (1.6 mm effective section thickness) can be acquired with a table speed of 9.4 mm/s, and a 2.5 mm nominal thick section (3.2 mm effective section thickness) can be acquired with an 18.8 mm/s table speed. The advantages of MDCT for imaging the vascular system can be broken down into three fundamental improvements over single detector-row CT scanners speed (faster), distance (longer), and section thickness (better). The focus of this article will be how multidetector-row CT technology has substantially improved aortoiliac and lower extremity arterial imaging.     

Advances in vascular and cardiac MDCT imaging: peripheral arteries

When compared to a standard dose of a relatively lowconcentration contrast material, the use of a small volume of iomeprol 400 yielded higher arterial enhancement from the abdominal aorta down to the femoral arteries with minimal or no venous overlap and without significant differences in terms of diagnostic output.     

Lesion enhancement in radio-frequency spoiled gradient-echo imaging: theory,experimental evaluation,and clinical implications.

PURPOSETo investigate the lesser lesion conspicuity after gadolinium contrast infusion with radio-frequency spoiled gradient-echo (SPGR) sequences relative to conventional T1-weighted spin-echo techniques.METHODSThe influences of repetition time, echo time, and flip angle on spin-echo and SPGR signal were studied with mathematical modeling of the image signal amplitude for concentrations of gadopentetate dimeglumine solute from 0 to 10 mM. Predictions of signal strength were verified in vitro by imaging of a doped water phantom. The effects of standard (0.1 mmol/kg) and high-dose (0.3 mmol/kg) gadoteridol on spin-echo and SPGR images were also investigated in three patients.RESULTSThe measured amplitude of undoped water and the rate of increase of doped water signal with increasing gadopentetate concentration (slope) for spin-echo 600/11/1/90 degrees (repetition time/echo time/excitations/flip angle) and SPGR (600/11/190 degrees) were similar and exceeded those of SPGR (35/5/145 degrees). Greater increases in SPGR doped water signal and its slope were produced by increasing TR than by varying echo-time or flip angle. The subjective lesion conspicuity and measured lesion contrast at 0.3 mmol/kg were greater with spin-echo (600/11/1/90 degrees) than with SPGR (35/5/145 degrees) in all three patients; the measured lesion enhancement was similar for both techniques in two patients and decreased for SPGR in the third patient.CONCLUSIONSThe phantom studies suggest that the short repetition time of 35 msec, typically used in clinical SPGR imaging, is largely responsible for a reduced signal amplitude and a diminished rate of increase of signal with increasing gadopentetate concentration, relative to spin-echo. Phantom and clinical studies suggest that the dose of paramagnetic agent required to achieve SPGR lesion conspicuity with short repetition time comparable with spin-echo would have to be higher than the dose in current clinical use.     

腰疝的CT影像表现对临床诊治的价值分析

目的探讨腰疝的CT影像学表现对临床诊治的价值。方法对6年间25例腰疝患者27个疝囊的诊断、治疗及CT影像学表现等进行回顾性总结和分析。结果腰上三角疝23个,腰下三角疝2个,腰上下三角疝均累及2个。疝环直径大小约1.4～13.7cm,其中4cm以下18个,4～6cm 6个,疝环大于7cm 3个;疝囊2.0cm×1.3cm～11.5cm×5.9cm,其疝出内容物的大小与疝环不成比例;疝出内容物:3例结肠,1例结肠和回肠,合并小肠梗阻,其余均为脂肪组织及系膜。18例上界为12肋下缘,7例为11肋下缘,疝环越大者周围肌群均较薄弱。5例手术,随访未见复发。结论 CT能明确疝环的大小,周围腹壁肌群薄弱程度,与骨组织的关系,还能提示疝内容物的性质和进一步排除其它性质的病变,依据影像学表现指导临床选择合适的手术方式。