Detection of endograft fractures with multidetector row computed tomography

Delayed endograft metallic strut failures detected in vivo with multidetector row computed tomography (MDCT) are reported in two patients who underwent endovascular abdominal aortic aneurysm repair with AneuRx and Talent endografts. In both instances, nitinol fractures were associated with proximal migration and type I endoleak. In both cases, the metallic strut fractures were detected with transverse sections from 16-channel MDCT angiograms and confirmed by using volume rendering. These cases highlight the previously unreported ability of thin-section, high-resolution MDCT angiography to detect endograft strut fractures.     

A comparison of conventional radiography and computed tomography in the evaluation of spiral fractures of the tibia

Spiral fractures of the distal third of the tibial shaft can have problems of malunion or non-union that may be related to inability to assess the quality of the initial reduction of the fracture. We created typical two-fragment torsional tibial fractures in cadaver bones. The fracture fragments were mounted in a specially constructed jig that allowed simulation of various malreduction positions including varus and valgus angulation, antecurvatum, recurvatum, malrotation, and shortening. Anteroposterior and lateral radiographs and computed tomographic scans of the specimens were made. Measurements of the fracture gap were made at defined distances along the fractures, directly on the specimens as well as on the radiographs and computed tomographic scans. Excellent correlation was obtained between measurements of the gap on the specimens and on the computed tomographic scans, but plain radiographic measurements in thirty of thirty-four instances underestimated the true width of the gap. When shortening was introduced larger maximum gaps (of as much as eighteen millimeters) as well as greater discrepancies between measurements on the scans and plain radiographs were seen. The sizes of the fracture gaps were also greater for a given degree of shortening when the pitch of the spiral fracture was greater.     

Noninvasive evaluation of arterial grafts with newly released multidetector computed tomography

BACKGROUND: High-quality postoperative imaging of bypass conduits is essential when evaluating different types of conduits, anastomoses, and surgical techniques. We investigated the potential value of the newest generation of multidetector-row computer tomographic scanners in assessing bypass grafts. METHODS: From June to September 2002, 14 patients underwent scanning with a newly released 16-slice computed tomographic scanner (Mx8000 IDT; Philips Medical Systems) after coronary artery bypass grafting. Four patients had had minimally invasive direct coronary artery bypass grafting and 3, redo coronary artery revascularization. Contrast-enhanced computed tomographic angiography was performed using retrospective electrocardiographic gating. Scan length was 22 to 30 cm, and total scan time was 27 to 37 seconds. RESULTS: Of the 14 patients, 8 were scanned within 1 week after operation and 6, 1 month to 12 months postoperatively. Average heart rate during the scan was 82 beats per minute (range, 60 to 97 beats per minute), and all patients were able to hold their breath for the required time. Thirty conduits were studied: 26 arterial (18 in situ left and right internal mammary artery grafts, five free right internal mammary and radial artery grafts, and three in situ right gastroepiploic artery grafts) and four vein grafts. Excellent visualization of all 30 grafts was achieved. Thirty-four of the 35 distal anastomoses were patent; one vein graft was occluded. CONCLUSIONS: This new technology is a promising noninvasive measure to evaluate patency of bypass conduits, including the gastroepiploic artery where catheterization is usually difficult. The ability to display the vessel wall as well as its lumen might distinguish radial artery spasm from intimal hyperplasia. The superb resolution and increased scan length required to cover the entire internal mammary artery grafts-from origin to distal anastomoses-can be achieved easily in a single breath-holding owing to the increased number of slices per rotation and shortening of the gantry rotation time.     

Nonvascular complications in pediatric liver recipients: multidetector computed tomography evaluation

In pediatric liver transplantation postoperative diagnosis of complications is crucial for graft salvage. Multidetector computed tomography (MDCT) is a technique to evaluate complications. In this study we present nonvascular abdominal complications encountered in pediatric recipients after liver transplantation. We retrospectively examined 113 MDCT examinations in 43 pediatric patients who underwent liver transplantation between 1997 and 2005. Computed tomography (CT) examinations were made by a 16-detector multislice CT scanner. The pathological findings on CT images were: intraperitoneal free fluid, intrahepatic bile duct dilatation, graft liver infarction, perihepatic and intraperitoneal fluid collections (six biloma), colonic and/or intestinal dilatation, splenic infarction, perihepatic hematoma, right adrenal hemorrhage, perihepatic abscess, incisional hernia, intrahepatic biloma and periportal collar. In one patient intestinal hemorrhage was suspected. Intestinal perforation was suspected in three patients. Among these three patients, one patient died before any surgical intervention. In two patients the diagnosis was confirmed at surgery. In pediatric patients, the short examination time, brief sedation duration, and high-resolution images make MDCT an effective radiological method to evaluate nonvascular transplant complications.     

Evaluation of posterior clinoid process pneumatization by multidetector computed tomography

In the present study, we investigated the types and ratio of posterior clinoid process (PCP) pneumatization in paranasal sinus multidetector computed tomography (MDCT). Paranasal MDCT images of 541 subjects (227 males, 314 females), between 15 and 65 years old, were included into the study. Pneumatization of anterior clinoid process and pneumatization types (I, II, or III) were evaluated in the males and females. PCP pneumatization was detected in 20.7 % of the males and 11.5 % of the females. Right, left, and bilateral PCP pneumatizations were detected in 7.9, 5.7, and 7.0 % of the males and 2.9, 3.2, and 4.5 % of the females, respectively. PCP pneumatization of the males is significantly higher than the females. The most detected type of pneumatization was type I (61.2 %) for all groups. In right, left, and bilateral pneumatizations separately, type I pneumatization was the most detected pneumatization type with the ratio of the 70.4, 65.2, and 50.0 %, respectively. In males, type I (61.7 %), and similarly in females, type I (60.6 %) pneumatization were detected more. Type II and type III pneumatizations were detected in decreasing order in both groups. In younger subjects, pneumatization of posterior clinoid process was found as higher, and in older subjects, PCP pneumatization was found as lower. Sclerosis process related to the aging may be responsible for the lower pneumatization ratios in older subjects. Structure of the surrounding regions of PCP is important for surgical procedures related to cavernous sinus, basilar apex aneurysms, and mass lesions. Preoperative radiological examinations are useful for operative planning. Any anomalies to PCP can cause unnecessary injury to the neurovascular complex structure around the cavernous sinus or postclinoidectomy CSF fistulas. Posterior clinoidectomies should be avoided in patients with type III PCP pneumatization to prevent CSF fistulas.     

Preoperative assessment of hilar cholangiocarcinoma by multidetector row computed tomography

Background/Purpose Hilar cholangiocarcinoma is the one of the most difficult carcinomas to diagnose because of the localization of the main tumor at the hepatic hilus, and because of the complex anatomy of the biliary, artery, and portal systems. To perform a curative operation, it is important to evaluate the extent of carcinoma and the resectability. Hilar cholangiocarcinoma often extends along the axis of the bile duct. Percutaneous transhepatic cholangiogaraphy (PTC) and/or endoscopic retrograde cholangiography (ERC) are usually performed to diagnose the extent of the hilar cholangiocarcinoma. However, computed tomography (CT) was thought not to be useful because its resolution is poor. Now that multidetector row CT (MDCT) and high-performance imaging systems are available, the diagnostic strategy for hilar cholangiocarcinoma has changed. Methods In this study, we analyzed the preoperative diagnostic imaging of 24 consecutive patients whose hilar cholangiocarcinoma was confirmed by histopathological examination. All patients were submitted to 16-channel MDCT, except for those with an allergy to iodine contrast medium. The data obtained from MDCT were analyzed and checked by both radiologists and surgeons, using multiplanar reconstruction (MPR) images. Results The accuracy of diagnosis of horizontal spreading was 80.9% and that of vertical spreading was 100%. However, the sensitivity for lymph node metastasis was insufficient. Based on the data from MDCT and other examinations, all patients underwent surgery. Curative operation was performed in 15 patients (62.5%). Conclusions Our results indicate that 16-channel MDCT is reliable for the diagnosis of hilar cholangiocarcinoma, especially prior to bile duct drainage. Thus, it is important to perform MDCT when patients with obstructive jaundice are encountered.     

Preoperative evaluation of the longitudinal spread of extrahepatic bile duct cancer using multidetector computed tomography

Background/Purpose  The aim of this study was to compare the diagnostic accuracy of multidetector computed tomography (MDCT) and direct cholangiography in evaluating the longitudinal spread of extrahepatic bile duct cancer. Methods  Images obtained from a 16-detector row scanner (MDCT) and from direct cholangiography (via either endoscopic naso-biliary drainage or percutaneous transhepatic biliary drainage) of 47 patients with histopathologically proven extrahepatic bile duct cancer were retrospectively interpreted. Differences between measures of longitudinal tumor spread determined by each modality and measures of macroscopic spread in resected specimens were assessed and compared. Results  Assessments carried out using MDCT differed significantly less from the macroscopic measurements than those made using direct cholangiography (P < 0.0001). Provided the diagnosis was defined as being accurate, based on a diagnostic difference of within ±5 mm, the diagnostic accuracy of MDCT (96%) was significantly higher than that of direct cholangiography (70%) (P = 0.028). Preoperative evaluation with direct cholangiography resulted in a 30% underestimation of the incidence. Conclusion  MDCT is superior to direct cholangiography for evaluating the preoperative longitudinal extent of bile duct cancer. Consequently, the utility of MDCT for preoperative evaluation of extrahepatic bile duct cancer warrants further examination.     

Sixteen-slice multidetector computed tomography for graft patency evaluation after coronary artery bypass surgery

OBJECTIVE: To investigate the ability of 16-slice multidetector computed tomography (MDCT) to assess coronary artery bypass graft patency and to detect bypass stenosis by comparison with coronary angiography. METHODS: Thirty patients underwent both conventional coronary bypass angiography and retrospective ECG gated 16-slice multidetector computed tomography after surgery using 0.4 seconds rotation time and 1.25 mm slice thickness. RESULTS: Among a total of 107 bypass grafts, 101 grafts (94.4%) were evaluable by MDCT. Thirteen patients were taking oral beta blockers. Mean heart rate was 73.6 (52-105). Of the 40 internal mammary arteries and two radial arteries examined, only one was occluded by coronary bypass angiography and MDCT, resulting in a sensitivity of 100% and a specificity of 100%. MDCT correctly diagnosed all patent venous grafts and missed two of the 14 venous grafts shown occluded by conventional angiography resulting in a sensitivity of 85.7% and specificity of 100%. When occluded grafts were excluded, MDCT did not detect two out of two anastomotic arterial graft stenosis >50% and resulted in one false positive result for a sensitivity and specificity of 0% and 97.4%, respectively. MDCT correctly diagnosed one out of three venous stenosis >50% and falsely diagnosed one venous graft stenosis >50% yielding a 33.3% and 97.6% sensitivity and specificity, respectively. CONCLUSION: Sixteen-slice MDCT allows for noninvasive evaluation of coronary bypass grafts patency with high diagnostic accuracy. Assessment of distal anastomotic stenosis was deficient, particularly for arterial grafts, still limited by low resolution or artifacts. Improved accuracy may be obtained by more aggressive heart rate reduction.     

Preoperative morphological assessments of congenital heart disease by multidetector computed tomography

Preoperative morphological assessments and anatomical delineation are keys to treatment of adult patients with congenital heart disease. We report on 2 cases where morphological assessments by multidetector-row computed tomography (MDCT) were useful. Case 1. A 33-year-old male was diagnosed with atrial septal defect (ASD) complicated by mitral regurgitation (MR), tricuspid regurgitation (TR), and severe pulmonary hypertension. In establishing the diagnosis, we carefully examined and confirmed that there was no possibility of ostium primum defect or other complicating malformations. MDCT was useful for demonstrating the location and morphology of the defect, anatomical relation to the tricuspid ring and the presence or absence of complicating malformations. Case 2. A 61-year-old female was diagnosed with double-chambered right ventricle with an intraventricular pressure gradient of 80 mmHg. MDCT extensively and clearly delineated the position and shape of abnormal muscle bundles and the morphology of complicating ventricular septal defect (VSD). MDCT was also useful in the determination of specific surgical procedures and the quick understanding of the anatomy during surgery, and even in postoperative assessments of therapeutic effects.     

Radiographic evaluation of cervical spine trauma. Plain radiography and conventional tomography versus computed tomography

Different imaging modalities are available for the diagnosis of cervical spine injuries. There is a controversial discussion about whether plain radiography (PR), conventional tomography (CTO) or computed tomography (CT) should primarily be used. PR and CTO are more often available and less costly than CT. Especially in second-care hospitals, CT is not always available. The diagnostic work-up in these centres has to rely on conventional techniques. The aim of this study was to define the role of PR supplemented by CTO in the diagnosis of cervical spine trauma in comparison to CT. Twenty-five patients were identified who underwent plain radiography (PR), conventional tomography (CTO) and computed tomography (CT) for the diagnosis of a cervical fracture. In 19 patients a fracture of the cervical spine was identified. All images were reviewed by two independent observers to estimate the interobserver variability. The highest detection rate was achieved by CT (18/18 fractures detected for observer 1/2), followed by CTO (16/16 fractures) and then PR (15/14 fractures). When the detection rates of PR and CTO are combined, 18 fractures were detected by each of the observers. The results were analysed for the dens and the rest of the cervical spine independently. For PR and CTO the detection rates were lower for fractures of the dens than for the rest of the cervical spine. We conclude that the combination of PR and CTO accurately detects fractures of the cervical spine compared with CT. If a fracture of the dens is suspected, the patients should be referred to CT due to its superior accuracy in this region. Received: 25 April 2000     

Preoperative evaluation of the aberrant artery in intralobar pulmonary sequestration using multidetector computed tomography angiography

Intralobar pulmonary sequestration is a rare congenital malformation of the lung, and identification of the aberrant artery from the systemic circulation to the sequestered lung is crucial in definitive surgery. Nowadays, various noninvasive imaging modalities such as helical computed tomography, magnetic resonance imaging, and color Doppler sonography have been developed. Among them, multidetector computed tomography angiography, which allows simultaneous imaging of the aberrant artery and venous drainage, has the potential to become the first-line examination in the preoperative assessment of pulmonary sequestration. In this article, we describe 2 cases of intralobar pulmonary sequestration, in which multidetector computed tomography angiography was useful in the preoperative management and surgery was successfully performed.     

Gallium scanning by conventional imaging and emission computed tomography in the pretreatment evaluation of lung cancer.

Gallium 67 citrate was evaluated with conventional scanning and emission computed tomography (CT) scanning as a method of pretreatment staging of the intrathoracic, especially mediastinal, spread of lung cancer. Of 31 patients with tumours of various histological types, the isotope was concentrated in the primary lesion in all but one. In 10 out of 12 patients who underwent surgical exploration conventional gallium scanning correctly indicated the mediastinum to be clear and identified two other patients with a tumour of the mediastinum not recognised by chest radiography or emission CT gallium scanning. Neither conventional nor emission CT gallium scanning produced false positive images. Conventional gallium scanning can give information about the mediastinum not available from chest radiographs or bronchoscopy.