Diagnostic accuracy of multislice computed tomography coronary angiography is improved at low heart rates

Purpose: Assess the effect of heart rate on diagnostic accuracy for the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). Material and methods: About 120 patients (105 males; 59±11 years) with suspected coronary artery disease who underwent conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA (Sensation 16, Siemens, Germany), with the following protocol: collimation 16×0.75 mm, gantry rotation time 420 ms, feed/rotation 3.0 mm, kV 120, mAs 400–500. The protocol for contrast material administration was 100 ml of Iodixanol (Visipaque 320 mg l/ml, Amersham, UK) at 4 ml/s and the delay was defined with a bolus tracking technique. In all patients the mean heart rate (HR) during the scan was used as a criteria to divide the population in two groups of 60 patients each. In one group (Low HR) the 60 patients with lower heart rates, and in the other group (High HR) the patients with higher heart rates. In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (≥50% lumen reduction) was evaluated in vessels ≥2 mm of diameter using quantitative CA as reference standard. The difference in diagnostic accuracy were compared with a Chi² test and a p<0.05 was considered significant. Results: There was no significant difference between the two groups regarding age, gender, weight, mean intravascular attenuation, and calcium score. Overall 1310 (652 for Low HR and 658 for High HR) segments with 219 (105 for Low HR and 114 for High HR) significant lesions were available for the analysis. The average heart rate was 52±4HU and 63±5HU for Low HR and High HR, respectively (p<0.001). The sensitivity and specificity were 92 and 96% for Low HR and 90 and 92% for High HR (p<0.05). There were 22 vs. 44 false positives, and 8 vs. 12 false negatives in the Low HR and High HR, respectively. Conclusion: Increasing HR significantly deteriorates diagnostic accuracy in MSCT-CA.     

The “spoke wheel” sign in hepatic focal nodular hyperplasia

Abdominal Radiology -     

Ischemic and non-ischemic dilated cardiomyopathy

Dilated Cardiomyopathy is a high-incident disease, which diagnosis of and treatments are clinical priority. The aim of our study was to evaluate the diagnostic potential of cardiac magnetic resonance (CMR) imaging; echocardiography and the biochemical parameters that can help us differentiate between the post-ischemic and non-ischemic dilated cardiomyopathy. Materials and methods. The study enrolled 134 patients with dilated cardiomyopathy: 74 with the post-ischemic form and 60 with the non-ischemic one. All patients underwent a coronary imaging test, with echocardiogram, cardiac magnetic resonance and a blood test. Pro-inflammatory cytokines were evaluated using Luminex kit. Data was compared between the two groups. Results. Echocardiography allowed recognition of Left Ventricular Non Compaction in 2 patients. Longitudinal and circumferential strains were significantly different in the two groups (p<0.05). Using CMR imaging a post-myocarditis scar was diagnosed in 2 patients and a post-ischemic scar in 95% of patients with the chronic ischemic disease. The interleukin IL-1, IL-6 and TNF-α levels were higher in the post-ischemic group compared with the non-ischemic one. Conclusions. The use of second level techniques with a high sensitivity and specificity would help distinguish among different sub-forms of dilated cardiomyopathy.     

Imaging findings of hepatic focal nodular hyperplasia in men and women: are they really different?

Purpose

This study was undertaken to compare the imaging findings of focal nodular hyperplasia (FNH) in men and women, as seen on multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS).

Materials and methods

Two radiologists reviewed 195 imaging studies (17 MDCT, 81 MRI and 97 CEUS examinations) pertaining to 111 FNHs (mean size 3 cm) in 91 patients (mean age 39 years). For each lesion, the readers assessed size, location, echogenicity, attenuation, or signal intensity in comparison with adjacent liver parenchyma on both unenhanced and postcontrast images.

Results

Eighty-nine FNHs (mean size 3.1 cm) were observed in 73 women (mean age 37.9 years) and 22 FNHs (mean size 2.7 cm) in 18 men (mean age 41.2 years). No statistically significant differences were found between men and women in terms of age, FNH lesions per patient (1.22 and 1.21, respectively), size, baseline and enhancement pattern on MRI, CEUS and MDCT (p < 0.05). A central scar in FNHs was depicted in 4/18 (22.2 %) men and 16/63 (25.4 %) women on MRI (p < 0.05), and in 1/2 (50 %) men and 7/15 (46.7 %) women on MDCT (p < 0.05), whereas a spoke-wheel pattern, central scar, and/or feeding vessel were seen in 5/17 (29.4 %) men and 22/80 (27.5 %) women on CEUS (p < 0.05).

Conclusions

Our results did not show any differences in imaging features, age of occurrence and size of FNH between men and women.     

Image assessment with multislice CT coronary angiography

AIM: To investigate the diagnostic accuracy of two different protocols for image evaluation used in multislice computed tomography coronary angiography (MSCT-CA). MATERIALS AND METHODS: Sixty patients with suspected coronary artery disease undergoing conventional coronary angiography (CA) were enrolled for MSCT-CA. All patients underwent 16-row MSCT (Sensation 16, Siemens, Germany) with the following parameters: detector rows 16, collimation 0.75 mm, gantry rotation time 375 ms. Two independent observers assessed the images for significant stenosis using a a protocol with standard projections and a three-dimensional protocol. The diagnostic accuracy for both methods was calculated using quantitative CA as a reference standard. RESULTS: The sensitivity, specificity, negative predictive value and positive predictive value obtained with the conventional projection protocol and with three-dimensional protocol were: 54% and 93%, 97% and 97%, 76% and 86%, 92% and 99%, respectively. CONCLUSIONS: Conventional projections in the assessment of MSCT-CA provide insufficient diagnostic accuracy compared with three-dimensional processing.     

Abdominal splenosis and its differential diagnoses: What the radiologist needs to know

Splenosis is a benign acquired condition characterized by the presence of heterotopic viable splenic tissue in other organs or within cavities such as peritoneum, retroperitoneum, or thorax after splenic trauma or surgery. Abdominal splenosis is often an incidental finding and computed tomography and magnetic resonance usually allow a confident diagnosis. The typical enhancement that parallels the spleen is a useful hallmark of splenosis. Splenic implants lack contrast uptake in the hepatobiliary phase and show high signal at high b-values on diffusion-weighted images. In some cases splenosis may mimic malignant and benign conditions in the peritoneum as well as in hollow and parenchymal abdominal organs and further investigations – including scintigraphy with Tc99m-labelled heat-denatured red blood cells or biopsy – are sometimes required in challenging cases. This pictorial essay reviews the imaging presentation and potential differential diagnosis of splenosis according to the site of implantation. A prompt and accurate radiological diagnosis of splenosis can avoid unnecessary biopsy or surgery.     

Acquired immunodeficiency syndrome and pulmonary Mycobacterium xenopi infection. Role of computerized tomography

INTRODUCTION: Mycobacterium xenopi is one of the most common agents responsible for nontubercular mycobacterial pulmonary disease on AIDS patients. These lesions have been studied with conventional radiography, while CT has been used in patients with aspecific mycobacterioses or non-AIDS pulmonary conditions from Mycobacterium xenopi. PURPOSE: We investigated the yield of CT in the study of lung lesions from Mycobacterium xenopi in AIDS patients. MATERIAL AND METHODS: We examined 12 AIDS patients with pulmonary lesions from Mycobacterium xenopi, patients age ranged 30 to 46 years. All patients had CD4 blood levels lower than 250 cells/mL and Mycobacterium xenopi in the sputum. All patients underwent a standard chest radiograph and a CT examination. CT images were evaluated by three radiologists independently and the definitive diagnosis was made in the presence of a fourth radiologist. RESULTS: Chest CT showed parenchymal consolidation in 66% of cases, associated with bilateral basal bands in 16% of cases. Consolidation was unilateral in 41% of cases and most frequently involved the right lower lobe. Bilateral reticular interstitial involvement was seen in the patients (41%). Micronodules in 1 patient (8%) and mediastinal adenopathy in 33% of cases. Two patients had pre-xisting emphysema and 1 had bronchiectasis. DISCUSSION AND CONCLUSIONS: The frequency of lung disease from Mycobacoerium xenopi has increased because of the spreading of the HIV infection. Such lung lesions in AIDS patients are aspecific in appearance and localization, which the clinical radiologist needs to consider to address treatment planning. The frequent finding of parenchymal consolidation and the absence of cavitary lesions may be referred to the poor capability of AIDS to produce an adequate inflammatory response. The lung lesions tend to distribute in the lower lobes unilaterally. Adenopathy was also a frequent finding. CT plays a fundamental role in studying the chest of these patients because it permits to locate lung lesions with higher accuracy than conventional radiography and to detect adenopathies, micronodules reticular interstitial involvement and bronchiectases.     

Remote teaching in surgery: problem-based learning,telementoring, and evaluation tests

The authors propose the use of distant learning in the surgical knowledge teaching. The problem based learning methodology can support this new didactic approach. Telementoring is an interactive experimental methodology that allows young surgeons education by distant learning tutoring of an expert surgeon. The problem about assessment of efficacy and quality of computer-assisted instruction is to day under evaluation.     

Technical analysis of volume-rendering algorithms: application in low-contrast structures using liver vascularisation as a model

AIM: To assess the influence of pre-set volume-rendering opacity curves (OC) on image quality and to identify which absolute parameters (density of aorta, hepatic parenchyma and portal vein) affect visualization of portal vascular structures (low-contrast structures). MATERIALS AND METHODS: Twenty-two patients underwent a dual-phase spiral CT with the following parameters: collimation 3 mm, pitch 2, increment 1 mm. Three scans were performed: one without contrast medium and the latter two after the injection of contrast material (conventionally identified as 'arterial' and 'portal'). The images were sent to a workstation running on an NT platform equipped with post-processing software allowing three-dimensional (3D) reconstructions to generate volume-rendered images of the vascular supply to the liver. Correlation between the absolute values of aorta, liver and portal vein density, OC parameters, and image quality were assessed. RESULTS: 3D images generated using pre-set OC obtained a much lower overall quality score than those produced with OC set by the operator. High contrast between the liver and the portal vein, for example during the portal vascular phase, allows wider windows, thus improving image quality. Conversely, the OC in the parenchymal phase scans must have a high gradient in order to better differentiate between the vascular structures and the surrounding hepatic parenchyma. CONCLUSIONS: Image features considered to be of interest by the operator cannot be simplified by the mean of pre-set OC. Due to their strong individual variability automatic 3D algorithms cannot be universally applied: they should be adapted to both image and patient characteristics.