Multidetector computed tomography (MDCT) in the diagnosis of pulmonary embolism: interobserver agreement among radiologists with varied levels of experience

Purpose: To assess the interobserver variability of radiologists with varied levels of experience in the interpretation of multidetector computed tomography (MDCT) pulmonary angiographies.

Material and Methods: Review of CT pulmonary angiographies performed on patients included in a diagnostic study evaluating a decision-based algorithm for diagnosing pulmonary embolism (PE). Five radiologists, three board-certified general radiologists and two radiology trainees with 2 years' experience, participated in the study.

Results: According to the consensus reading, PE was present in 91 (31%) and absent in 194 (67%) patients, while in five patients (1.7%) the interpretations were regarded as equivocal. The per-patient agreement on the diagnosis of PE achieved by each of the four readers compared to the consensus reading was very good (κ range 0.85-0.92), but peripheral emboli were missed in four to six patients by three of four observers. The agreement on the most proximal level of PE (per-proximal level) assessed by mean κ value was 0.83 (κ range 0.68-0.91) for the detection of proximal emboli, 0.61 for segmental emboli (κ range 0.40-0.80), and 0.38 for emboli in the subsegmental vessels (κ range 0.0-0.89).

Conclusion: The overall agreement on the diagnosis of PE by MDCT for general radiologists and radiology trainees is very good, and we therefore believe that the initial management of patients with suspected PE could be based on the preliminary assessment performed by on-call radiologists with 2 years of experience.     

Focused helical appendiceal computed tomography: Technique and interpretation

This article reviews a focused helical appendiceal computed tomographic technique and discusses an approach to appendiceal computed tomographic interpretation.     

Infectious sacroiliitis: value of computed tomography (CT) and magnetic resonance imaging (MRI)

Infectious sacroiliitis is an uncommon septic arthritis, the diagnosis of which is difficult to establish. We retrospectively examined 14 cases of septic sacroiliitis, by CT (two of whom also had an MRI examination). The patient population consisted of eight men and six women; 9 were African, 8 had tuberculous sacroiliitis and 6 pyogenic sacroiliitis. All the cases showed a pre-sacroiliac soft tissue swellilng with ring-like enhancement following intravenous contrast in eight cases. A gas image was observed at the centre of the abcess in two cases. Joint narrowing was found in four patients and widening in eight, associated with an image of bone sequestration in seven, CT gave an etiologic orientation in 8 cases, and facilitated the guidance of bone biopsy. MRI showed low signal T1-weighted images and high signal T2 of the subchondral bone, joint space and soft tissue abcess. We conclude that CT is helpful in the evaluation of infectious sacroiliitis, and that further studies are necessary to evaluate the role of MRI in such pathologic processes.     

Four-dimensional computed tomography (4D CT)--concepts and preliminary development

Four-dimensional computed tomography (4D CT) is a dynamic volume imaging system of moving organs with an image quality comparable to that of conventional CT. 4D CT will be realized by several technical breakthroughs for dynamic cone-beam CT: (1) a large-area two-dimensional (2D) detector; (2) high-speed data transfer system; (3) reconstruction algorithms; (4) ultra-high-speed reconstruction computer; and (5) high-speed, continuously rotating gantry. Among these, development of the 2D detector is one of the main tasks because it should have as wide a dynamic range and as high a data acquisition speed (view rate) as present CT detectors. We are now developing a 4D CT scanner together with the key components. It will take one volume image in 0.5 sec with a 3D matrix of 512 x 512 x 512. This paper describes the concepts and designs of the 4D CT system, as well as preliminary development of the 2D detector.     

Imaging of aortic dissection by helical computed tomography (CT)

Aortic dissection is the most frequent cause of aortic emergency, and its outcome is still frequently fatal. The management of this pathology has changed with the development of endovascular means. Nowadays, imaging modalities are helpful in management decision-making by providing information such as identification of entry tears along the aorta and involvement of the visceral branches of the abdominal aorta. Multi-slice CT scanning now appears to be the modality of choice for complete examination of the entire aorta. We review the parameters of image acquisition and contrast injection; appearances on CT of acute and chronic dissection are illustrated. Diagnostic pitfalls in CT imaging of acute dissection are discussed. Imaging of the post-surgical aorta and of chronic dissection is outlined. Intra-mural hematoma and penetrating aortic ulcer are subtypes of aortic dissection, and their appearances on CT scanning are also presented.     

Abdominal complications of chemotherapy: findings at computed tomography

Modern chemotherapy may result in an array of complications that can produce computed tomography (CT) findings in the hepatobiliary, gastrointestinal and urinary systems. This article describes the CT findings that may be seen in abdominal complications of contemporary chemotherapy. Knowledge of the varying CT appearances that can be encountered may facilitate both diagnosis and management in such cases.     

Iodide and xenon enhancement of computed tomography (CT) in multiple sclerosis (MS)

Summary The characteristic findings on computed tomography (CT) in multiple sclerosis (MS) are discussed. In a series of 49 cases plain CT was normal in 21 (43%), cerebral atrophy alone was present in 17 (35%) and plaques were visible in 11 (23%). These were most often adjacent to the lateral ventricles (14 plaques) and in the parietal white matter (10 plaques).CT was performed after the intravenous administration of iodide in 16 of these cases. Three of the low attenuation and three additional isodense lesions enhanced. Two patients with low attenuation plaques were scanned with xenon enhancement; the plaques absorbed less xenon than the corresponding contralateral brain substance and additional, previously isodense plaques were revealed. In one case the white matter absorbed much less xenon than normal and its uptake relative to grey matter was reduced.EMI Research Fellow     

Multi-detector computed tomography (MDCT) imaging of cardiovascular effects of pulmonary embolism: What the radiologists need to know

Background

Patients with pulmonary embolism have high mortality and morbidity rate due to right heart failure and circulatory collapse leading to sudden death. Multi-detector computed tomography MDCT can efficiently evaluate the cardiovascular factors related to pulmonary embolism.

A positron emission tomography/computed tomography (PET/CT) acquisition protocol for CT radiation dose optimization

BACKGROUND: In current combined positron emission tomography/computed tomography (PET/CT) systems, high-quality CT images not only increase diagnostic value by providing anatomic delineation of hyper- and hypometabolic tissues, but also shorten the acquisition time for attenuation correction compared with standard PET imaging. However, this technique potentially introduces more radiation burden to patients as a result of the higher radiation exposure from CT. METHODS: In this study, the radiation doses delivered from typical germanium-based and CT-based transmission scans were measured and compared using an anthropomorphic Rando Alderson phantom with insertions of thermoluminescent dosimeters. Image geometric distortion and quantified uptake values in PET images with different manipulating CT acquisition protocols for attenuation correction were also evaluated. RESULTS: It was found that radiation doses during germanium-based transmission scans were almost negligible, while doses from CT-based transmission scans were significantly higher. Using a lower radiation dose, the CT acquisition protocol did not significantly affect attenuation correction and anatomic delineation in PET. CONCLUSIONS: This study revealed the relation between image information and dose. The current PET/CT imaging acquisition protocol was improved by decreasing the radiation risks without sacrificing the diagnostic values.     

A case report of Fournier's gangrene: Imaging ultrasound and computed tomography (CT) scan

Necrotizing fasciitis and/or Fournier''s Gangrene is a rare, life-threatening soft tissue infection that, if not treated promptly, can immediately develop into systemic toxicity. It affects the genital, perineal, and perineal tissues, predominantly affecting men but can be seen in women. The diagnosis is often made clinically but radiologic examinations are helpful to determine the extent of the infection and can aid preoperative planning. Treatment consists of immediate and aggressive surgical debridement of necrotized tissue, broad-spectrum antibiotics, and early resuscitation. Here, we present a 56-year-old male patient with Fournier''s gangrene and describe the physical examination, bedside sonographic, and computed tomography findings. These findings can aid in the evaluation of patients with worrying symptoms so that antibiotics can be administered immediately and specialists can be consulted as needed.     

Comparative study of computed tomography (CT) and carotid angiography (CAG) in stroke patients

Summary The findings in CT and in CAG were compared in 173 stroke patients to evaluate dependability in the localization of cerebral arterial occlusion and of infarction by CT, and to test the reliability of the angiographic and clinical diagnosis of a space-occupying lesion in patients diagnosed clinically as stroke cases. *** DIRECT SUPPORT *** A2404071 00018     

Significance of extrapancreatic findings in computed tomography (CT) of acute pancreatitis

Computed tomography (CT) has proven reliable in the early detection of acute haemorrhagic pancreatitis. In the present study the extrapancreatic changes at CT were studied in 60 patients with acute pancreatitis. The CT findings were correlated to the early "prognostic signs" by Ranson and the clinical course of the disease. All the patients with minor extrapancreatic changes recovered without complications. When moderate to severe extrapancreatic changes were seen the incidence of haemorrhagic pancreatitis and the risk of development of pseudocyst or abscess was high. In these patients a dynamic contrast enhanced CT should be done in order to select the patients with haemorrhagic pancreatitis.     

Discrimination of suppurative cholangitis from nonsuppurative cholangitis with computed tomography (CT)

PURPOSE: Suppurative cholangitis is characterized by obstruction, inflammation, and pyogenic infection of the biliary tract. This disease represents a true emergency. The purpose of this study was to compare the computed tomography (CT) findings between acute calculous suppurative and nonsuppurative cholangitis and to determine if there are findings that assist in the differential diagnosis. MATERIALS AND METHODS: Fifteen patients with acute suppurative cholangitis were enrolled in this study. Findings at endoscopic retrograde cholangiopancreaticography (ERCP) were the standard of reference for suppurative cholangitis. To compare the findings of suppurative cholangitis with those of nonsuppurative cholangitis, 35 patients with nonsuppurative cholangitis were randomly selected. The following findings were evaluated: the presence of papillitis, the presence of stones in the ampulla, the presence of intrahepatic stones, the presence of early inhomogeneous enhancement of the liver, the degree of bile duct dilatation, the degree of bile duct wall thickening and presence of cholecystitis. Sensitivity and specificity for each of the individual findings were calculated. Statistical analyses were performed the Pearson chi(2) test, Fisher's exact test and the Mann-Whitney U test. RESULTS: Papillitis showed the highest specificity 86% with 60% sensitivity. Marked inhomogeneous enhancement of the liver during the arterial phase showed 80% specificity with 60% sensitivity. In multivariate logistic analysis, papillitis and marked early inhomogeneous enhancement of the liver were the most significant predictors of acute suppurative cholangitis. The combination of these two CT findings improved specificity (97% specificity) for the diagnosis of suppurative cholangitis. CONCLUSION: Papillitis and marked early inhomogeneous enhancement of the liver were found to be the most discriminative CT findings for the diagnosis of acute suppurative cholangitis and the differentiation between suppurative and nonsuppurative cholangitis.     

Head computed tomography utilization and intracranial hemorrhage rates

Utilization of computed tomography scans (CTs) has increased dramatically in emergency departments in the USA. This study aimed to retrospectively determine the yield of CTs among all patients that received a CT of the head from 2001 to 2007, which is adjusted for patient volume. For secondary endpoints, we examined the yield of CT of the head for the following hemorrhages: (1) intracerebral, (2) subarachnoid, (3) subdural, and (4) epidural. In 2001, 3.3 head CTs were performed per 100 patients seen. This increased by 60 % to 5.2 per 100 in 2007 (p?=?0.005, R ²?=?0.82). This correlated with a nonsignificant decrease in the rate of intracranial hemorrhage found by CT from 3.6 per 100 CTs in 2001 (95 % confidence interval (CI)?=?2.7–4.5) to 3.0 per 100 in 2007 (95 % CI?=?2.5–3.6). There were no significant differences in “positive” rates for each subgroup of intracranial hemorrhage. Our study found that the utilization of head CTs increased dramatically, but there was a corresponding increase in the number of positive findings so that the overall yield of head CTs from 2001 to 2007 remained relatively constant.     

Double common bile duct: curved-planar reformatted computed tomography (CT) and gadobenate dimeglumine-enhanced MR cholangiography

We present the case of a 61-year-old female with double common bile duct (CBD) with an opening into the lesser curvature of the stomach. We discuss the role of curved-planar reformatted computed tomography (CT) and gadobenate dimeglumine (Gd-BOPTA)-enhanced T1-weighted MRI in confirming the diagnosis of this uncommon disease.     

Flat-detector computed tomography (FD-CT)

Flat-panel detectors or, synonymously, flat detectors (FDs) have been developed for use in radiography and fluoroscopy with the defined goal to replace standard X-ray film, film-screen combinations and image intensifiers by an advanced sensor system. FD technology in comparison to X-ray film and image intensifiers offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. Respective efforts date back a few years only, but FD-CT has meanwhile become widely accepted for interventional and intra-operative imaging using C-arm systems. FD-CT provides a very efficient way of combining two-dimensional (2D) radiographic or fluoroscopic and 3D CT imaging. In addition, FD technology made its way into a number of dedicated CT scanner developments, such as scanners for the maxillo-facial region or for micro-CT applications. This review focuses on technical and performance issues of FD technology and its full range of applications for CT imaging. A comparison with standard clinical CT is of primary interest. It reveals that FD-CT provides higher spatial resolution, but encompasses a number of disadvantages, such as lower dose efficiency, smaller field of view and lower temporal resolution. FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room.