Celiomesenteric anomaly demonstration by multidetector CT and volume rendering

Preoperative knowledge of vascular anomalies is critical to planning a surgical approach. We present a case of celiomesenteric anomaly. Multidetector CT and volume rendering give high quality angiograms and a multitude of perspectives that facilitate depiction and understanding of such anomalies.     

Cervical spine trauma: evaluation by multidetector CT and three-dimensional volume rendering

Multidetector-row computed tomography (CT) offers important advantages over conventional imaging modalities in the evaluation of the post-trauma cervical spine. It allows for faster scanning times, critical for triaging post-trauma patients as well as for eliminating motion artifacts, and allows for thinner collimation and the ability to achieve an isotropic data set which can be reformatted in any plane without loss of spatial resolution. In addition, three-dimensional volume-rendered reconstructions of images obtained using multidetector scanners can provide additional information in defining extent of injury, allowing neurosurgeons to see the fractures in any plane, simulating intraoperative views. 3D multidetector-row CT represents an advance in CT technology and can help ensure rapid, accurate evaluation of cervical spine injuries. Electronic Publication     

Intrahepatic portal venous variations: demonstration by helical CT during arterial portography

PURPOSE: We assessed the prevalence and types of intrahepatic portal venous variations by helical computed tomography performed with arterial portography (CTAP). METHODS: In 192 patients without evidence of vascular invasion or distortion, CTAP images were reviewed retrospectively to identify portal venous variations. RESULTS: Of the 192 patients examined, 10 (5.2%) had trifurcation, 5 (2.6%) had a right posterior segmental branch arising from the main portal vein, 5 (2.6%) had an absence of the horizontal segment of the left portal vein, and 1 (0.5%) had an absence of the left lateral segmental portal branch. Of the patients without a horizontal segment, two had a right-sided ligamentum teres associated with malposition of the gallbladder, while another had complete ramification of intrahepatic portal branches from an umbilical vein-like segment. In the patient missing the left lateral segmental branches, the right portal vein segments were subcapsularly located. CONCLUSION: Variations of the intrahepatic portal veins can be recognized on CTAP imaging. tomography-Portal vein, computed tomography.     

Pseudoenhancement of simple renal cysts: a comparison of single and multidetector helical CT.

PURPOSE: The purpose of this work was to compare the extent of pseudoenhancement (artifactual increase in measured attenuation of a simple cyst after contrast medium administration) in a phantom model on single detector and multidetector helical CT scanners. METHOD: The phantom consisted of four water-filled spheres varying in size from 8 to 28 mm, suspended in an aqueous contrast medium bath. Iodine concentration in the bath was varied: 0, 6, 12, and 24 mg/ml corresponding to attenuation values of 0, +108, +180, and +300 HU. The phantom was scanned on single detector and multidetector helical CT scanners during the same session. Collimation (1, 3, and 5 mm) and pitch (1 and 1.5:1, single detector; 3:1 and 6:1, multidetector) were varied at each concentration. All scans were performed at 140 kVp and 170 mA. The region of interest was measured at the center of each sphere. The effects were analyzed using a linear regression model. RESULTS: The degree of pseudoenhancement was more pronounced with increasing iodine concentration, decreasing cyst size, and wider collimation (all p = 0.0001). Pseudoenhancement was also more marked on the multidetector than the single detector scanner (p = 0.0001). At physiological levels of renal enhancement, the average pseudoenhancement was +18 HU for the single detector versus +23 HU for the multidetector scanner. Variation in pitch had no effect. CONCLUSION: Pseudoenhancement is greater on a multidetector than a single detector helical CT scanner and may exceed 20 HU at physiological levels of renal enhancement.     

MR portography: Preliminary comparison with CT portography and conventional MR imaging

Magnetic resonance (MR) imaging with arterial portography (MRAP) was compared with computed tomography with arterial portography (CTAP) and conventional MR imaging for preoperative evaluation of hepatic masses in eight patients (nine studies). Twenty contiguous, 10-mm-thick-section CTAP images were obtained. MR imaging included T1- and T2-weighted spin-echo and fast multiplanar SPGR (spoiled gradient-recalled acquisition in the steady state) techniques. For MRAP, 0.1 mmol/kg gadopentetate dimeglumine was injected into the superior mesenteric artery. Portographic-phase, 8-mm-thick-section, axial SPGR images were first obtained, followed by “systemic phase” SPGR images. Lesions were seen best on the portographic-phase MRAP images and were less conspicuous on the systemic-phase MRAP, CTAP and conventional MR images. Of 19 visualized lesions, 18 were seen with MRAP; however; five subcentimeter lesions seen with MRAP were not seen with conventional MR imaging or CTAP. Systemic recirculation of iodinated contrast material from the bolus and from previous angiography is a potential limitation of CTAP. For both CTAP and MRAP, optimal results are expected if all images are obtained during a single breath hold, within seconds of the onset of contrast agent administration.     

螺旋CT门静脉血管造影的成像技术及其临床应用价值

目的评价螺旋CT门静脉血管造影（CTP）的最佳成像技术及其临床应用价值。方法对60例正常和108例疑有肝脏疾病的患者作了最大强度投影（MIP）和表面遮盖法（SSD）CTP成像。使用不同的准直、延迟时间及扫描方向将正常组随机分为六组,定性和定量分析各组图像的差别。结果准直3.0～5.0mm,延迟时间45～50s,自足端方向扫描MIPCTP能同时显示4级以上门静脉分支和2级以上的肝静脉分支。CTP能直观地评价门静脉和肝静脉的位置、管径、有无门静脉受侵或癌栓形成,了解门静脉高压侧支循环的分布范围和程度。CTP有助于经颈静脉肝内门腔静脉分流术（TIPS）术前定位、Budd-Chiari综合症的诊断和术后随访。SSDCTP立体感强,但不利于细微结构和癌栓的显示。结论CTP是门静脉和肝静脉无创性检查的可靠方法,有较高的临床应用价值。     

Conjoined twins: multiorgan system evaluation by multidetector CT and 3D volume rendering.

Conjoined twins, though uncommon, continue to present some of the most challenging questions for current diagnosis and therapy. The myriad of presentations demands a thorough multisystemic imaging evaluation before fully informed therapeutic and ethical decisions can be made. We present an unusual case of asymmetric omphaloischiopagus conjoined twins who were evaluated by multidetector CT and 3D volume rendering. This single technique can provide a large amount of information from a single study that can negate the need for some other imaging tests and can complement those other tests that remain necessary. We would suggest that when a CT examination is considered to evaluate this condition, an imaging interpretation that is independent of acquisition plane and that has multisystem versatility should be considered.     

Visualization of abdominal arteries by super-high-flow venous injection using multidetector helical CT

The purpose in this study was to compare the ratio of visualization of upper abdominal arteries using MDHCT between the super-high-flow injection method (Group A) and the conventional injection method (Group B). The subjects ects were 200 patients who were randomly divided into Group A (100 patients) and Group B (100 patients). In Group A, visualization of the large arteries, including the CE, SMA, HA and LGA, was possible at a rate exceeding 96%, and that of the small arteries, including the DPA, SPDA, RGA and Cyst A, was more than 79%. Visualization of upper abdominal arteries was markedly improved by the super high flow injection technique.     

Assessment of lung volumes in pulmonary emphysema using multidetector helical CT: comparison with pulmonary function tests.

The purpose of this study is to evaluate the usefulness of multidetector helical CT (MDCT) with three-dimensional (3D) postprocessing for assessing the lung volume at inspiration and expiration of the pulmonary emphysema and for comparing it with pulmonary function tests. Percentage lung volume at the threshold of -930, -900, -810, -790, and -770 at expiration showed good correlation with FEV1, FEV1/FVC, and DLCO/Va. Excellent correlation was observed between percentage lung volume at the threshold of -900 and FEV1/FVC. CT densitometry at expiration showed better correlation than that at inspiration with pulmonary function tests. MDCT with 3D technique is useful for assessing the severity of pulmonary emphysema.     

Ectopic origin of bronchial arteries: assessment with multidetector helical CT angiography

The purpose of this study was to determine non-invasively the frequency of ectopic bronchial arteries (BA) (i.e., bronchial arteries originating at a level of the descending aorta other than T5-T6 or from any aortic collateral vessel) on multidetector-row CT angiograms (CTA) obtained in patients with hemoptysis. Over a 5-year period (2000–2005), 251 consecutive patients with hemoptysis underwent multidetector-row CT angiography of the thorax. From this population, 37 patients were excluded because of a suboptimal CTA examination (n = 19), the presence of extensive mediastinal disease (n = 15) or severe chest deformation (n = 3) precluding any precise analysis of the bronchial arteries at CTA. Our final study group included 214 patients who underwent a thin-collimated CT angiogram (contrast agent: 300 to 350 mg/ml) on a 4- (n = 56), 16- (n = 119) and 64- (n = 39) detector-row scanner. The site of origin and distribution of bronchial arteries were analyzed on transverse CT scans, maximum intensity projections and volume-rendered images. The site of the ostium of a bronchial artery was coded as orthotopic when the artery originated from the descending aorta between the levels of the fifth and sixth thoracic vertebrae; all other bronchial arteries were considered ectopic. From the studied population, 137 (64%) patients had only orthotopic bronchial arteries, whereas 77 patients (36%) had at least one bronchial artery of ectopic origin. A total of 147 ectopic arteries were depicted, originating as common bronchial trunks (n = 23; 19%) or isolated right or left bronchial arteries (n = 101; 81%). The most frequent sites of origin of the 124 ostiums were the concavity of the aortic arch (92/124; 74%), the subclavian artery (13/124; 10.5%) and the descending aorta (10/124; 8.5%). The isolated ectopic bronchial arteries supplied the ipsilateral lung in all but three cases. Bronchial artery embolization was indicated in 26 patients. On the basis of CTA information, (1) bronchial embolization was attempted in 24 patients; it was technically successful in 21 patients (orthotopic BAs: 6 patients; orthotopic and ectopic BAs: 3 patients; ectopic BAs: 12 patients) and failed in 3 patients due to an instable catheterization of the ectopic BAs; the absence of additional bronchial arterial supply and no abnormalities of nonbronchial systemic arteries at CTA avoided additional arteriograms in these 3 patients; (2) owing to the iatrogenic risk of the embolization procedure of ectopic BAs, the surgical ligation of the abnormal vessels was the favored therapeutic option in 2 patients. This study enabled the depiction of ectopic bronchial arteries in 36% of the studied population, important anatomical information prior to therapeutic decision making.     

Contrast enhancement for whole-body screening using multidetector row helical CT: comparison between uniphasic and biphasic injection protocols

OBJECTIVE: To investigate which is more suitable for whole-body screening with multidetector row CT (MDCT) during one breathhold, a uniphasic or biphasic injection protocol for contrast material. SUBJECTS AND METHODS: Sixty patients received a volume of 1.7 mL x weight (kg) with iopamidol 300 mg iodine/mL. The patients were randomized into two injection protocols: A) a fixed injection rate of 2.0 mL/sec with a 70 sec delay, B) administration of 80% of the contrast material in 40 sec, then administration of the remaining 20% in 20 sec with an 80 sec delay. A helical scan from the apex of the lung to the base of the pelvic cavity was performed during one breathhold. CT attenuation values of the thoracic aorta, pulmonary artery, abdominal aorta, portal vein, superior vena cava (SVC), suprarenal and infrarenal inferior vena cava (IVC), liver, and pancreas were measured. Two radiologists visually assessed the degree enhancement of the IVC. In addition, the two radiologists visually assessed artifacts caused by contrast material in the subclavian vein and SVC using a four-point scale. RESULTS: Enhancement of the SVC in protocol A was significantly better than that in protocol B (p=0.04). Enhancement of the infrarenal IVC and liver in protocol B was significantly better than that in protocol A (p<0.01, p<0.01). Renal enhancement in protocol B was significantly better than that in protocol A (p=0.02). In all patients with both protocols A and B, enhancement of the suprarenal IVC was visually graded as acceptable or good. In all patients with protocol B, enhancement of the infrarenal IVC was graded as acceptable or good. In only 2/3 of patients with protocol A, enhancement of the infrarenal IVC was graded as acceptable or good. There was no significant difference in artifacts in the subclavian vein between the two protocols (p=0.77). Artifacts in the SVC in protocol B were significantly fewer than those in protocol A (p<0.01). CONCLUSION: Protocol B was more suitable for whole-body screening than protocol A, because of better enhancement of the liver and infrarenal IVC and fewer artifacts in the SVC.     

Chronic intestinal pseudo-obstruction in adult patients: multidetector row helical CT features

Chronic intestinal pseudo-obstruction (CIPO) is a rare condition due to severe gastrointestinal motility disorder. Adult patients with CIPO experience symptoms of mechanical obstruction, but reliable clinical signs that may help distinguish between actual mechanical obstruction and CIPO are lacking. Additionally, abdominal plain films that commonly show bowel dilatation with air-fluid levels do not reach acceptable degrees of specificity to exclude actual obstruction. Therefore, most adult patients with CIPO usually undergo multiple and often fruitless surgery, often leading to repeated bowel resections before diagnosis is made. In these patients who present with abdominal signs mimicking symptoms that would warrant surgical exploration, multidetector-row helical CT (MDCT) is helpful to resolve this diagnostic dilemma. MDCT shows a diffusely distended bowel and helps to rule out a mechanical cause of obstruction, thus suggesting CIPO and obviating the need for unnecessary laparotomy. In adult patients with CIPO, MDCT may show pneumatosis intestinalis, pneumoperitoneum or intussusception. However, these conditions generally do not require surgery in patients with CIPO. This pictorial essay presents the more and less common MDCT features of CIPO in adult patients, to make the reader more familiar with this disease.     

门静脉癌栓螺旋CT及CT门静脉造影的诊断价值

目的：评价门静脉癌栓螺旋CT及其门静脉血管造影（CTP）的特征及诊断价值。方法：43例门静脉癌栓形成的患者作了螺旋CT平扫和增强扫描，30例进行了多平面重组（MPR）和CTP成像，15例患者治疗的作了CT随访。结果：螺旋CT轴位和MPR图像能清晰显示门静脉癌栓，直接的CT征象为门静脉增粗及充盈缺损23％在动脉期癌栓有不均匀强化；间接征象包括门静脉管壁强化（42％）、侧支循环形成（100％）、门静脉海绵样变（44％）及周围肝脏血流动力学的改变。CTP能直观地评价门静脉的癌栓位置、管径及阻塞程度和侧支循环的情况。CT扫描可很好地显示门静脉癌栓治疗后的变化情况。结论：螺旋CT轴位图像结合MPR和CTP图像，可以便完整的提供门静脉癌栓的全面资料。     

螺旋CT门静脉血管造影扫描参数和成像方法的优化

目的：探讨统螺旋CT门静脉血管造影（CTP）最佳的扫描参数和成像方法。方法：60例无肝脏疾病的患者随机分为六组,造影剂剂量2.0ml/kg,速率2.0～2.5ml/s,使用不同的准直、延迟时间及扫描方向进行扫描,用最大强度投影（MIP）和表面遮盖法（SSD）作CTP成像,定性和定量分析各级图像的差别。结果：延迟时间45～50s、自足端向头侧方向扫描MIP CTP能显示门静脉4～6级分支及肝静脉2级以上分支,3.0和5.0mm准直组的图像质量无显著性差异,后者的覆盖范围较大。MTP CTP有利于细小血管分支的显示,SSD有较强的立体感,但易受人为因素的影响。结论：准直为3.0～5.0mm,延迟时间45～50s,自足端方向扫描MTP CTP成像,能同时获得高质量的门静脉和肝静脉系统图像,必要是作SSD CTP观察血管的空间立体关系。