Impact of scar thickness on the assessment of viability using dobutamine echocardiography and thallium single-photon emission computed tomography - A comparison with contrast-enhanced magnetic resonance imaging

OBJECTIVES We sought to determine whether the transmural extent of scar (TES) explains discordances between dobutamine echocardiography (DbE) and thallium single-photon emission computed tomography (Tl-SPECT) in the detection of viable myocardium (VM). BACKGROUND Discrepancies between DbE and Tl-SPECT are often attributed to differences between contractile reserve and membrane integrity, but may also reflect a disproportionate influence of nontransmural scar on thickening at DbE. METHODS Sixty patients (age 62 +/- 12 years; 10 women and 50 men) with postinfarction left ventricular dysfunction underwent standard rest-late redistribution Tl-SPECT and DbE. Viable myocardium was identified when dysfunctional segments showed Tl activity >60% on the late-redistribution image or by low-dose augmentation at DbE. Contrast-enhanced magnetic resonance imaging (ceMRI) was used to divide TES into five groups: 0%, 75% of the wall thickness replaced by scar. RESULTS As TES increased, both the mean Tl uptake and change in wall motion score decreased significantly (both p < 0.001). However, the presence of subendocardial scar was insufficient to prevent thickening; >50% of segments still showed contractile function with TES of 25% to 75%, although residual function was uncommon with TES >75%. The relationship of both tests to increasing TES was similar, but Tl-SPECT identified VM more frequently than DbE in all groups. Among segments without scar or with small amounts of scar (50% were viable by SPECT. CONCLUSIONS Both contractile reserve and perfusion are sensitive to the extent of scar. However, contractile reserve may be impaired in the face of no or minor scar, and thickening may still occur with extensive scar. (C) 2004 by the American College of Cardiology Foundation.

Comparison between real-time three-dimensional echocardiography, T1-201 single photon emission computed tomography and cardiac magnetic resonance imaging in the quantitative assessment of left ventricular volumes

Left ventricular (LV) volumes have important prognostic implications in patients with chronic ischemic heart disease. We sought to examine the accuracy and reproducibility of real-time 3D echo (RT-3DE) compared to TI-201 single photon emission computed tomography (SPECT) and cardiac magnetic resonance imaging (MRI). Thirty (n = 30) patients (age 62±9 years, 23 men) with chronic ischemic heart disease underwent LV volume assessment with RT-3DE, SPECT, and MRI. Ano vel semi-automated border detection algorithmwas used by RT-3DE. End diastolic volumes (EDV) and end systolic volumes (ESV) measured by RT3DE and SPECT were compared to MRI as the standard of reference. RT-3DE and SPECT volumes showed excellent correlation with MRI (Table). Both RT- 3DE and SPECT underestimated LV volumes compared to MRI (ESV, SPECT 74±58 ml versus RT-3DE 95±48 ml versus MRI 96±54 ml); (EDV, SPECT 121±61 ml versus RT-3DE 169±61 ml versus MRI 179±56 ml). The degree of ESV underestimation with RT-3DE was not significant.

Automatic measurement of vertebral rotation in idiopathic scoliosis

Study Design. Development of an automatic measurement algorithm and comparison with manual measurement methods. Objectives. To develop a new computer-based method for automatic measurement of vertebral rotation in idiopathic scoliosis from computed tomography images and to compare the automatic method with two manual measurement techniques. Summary of Background Data. Techniques have been developed for vertebral rotation measurement in idiopathic scoliosis using plain radiographs, computed tomography, or magnetic resonance images. All of these techniques require manual selection of landmark points and are therefore subject to interobserver and intraobserver error. Methods. We developed a new method for automatic measurement of vertebral rotation in idiopathic scoliosis using a symmetry ratio algorithm. The automatic method provided values comparable with Aaro and Ho's manual measurement methods for a set of 19 transverse computed tomography slices through apical vertebrae, and with Aaro's method for a set of 204 reformatted computed tomography images through vertebral endplates. Results. Confidence intervals (95%) for intraobserver and interobserver variability using manual methods were in the range 5.5 to 7.2. The mean (+/- SD) difference between automatic and manual rotation measurements for the 19 apical images was -0.5 degrees +/- 3.3 degrees for Aaro's method and 0.7 degrees +/- 3.4 degrees for Ho's method. The mean (+/- SD) difference between automatic and manual rotation measurements for the 204 endplate images was 0.25 degrees +/- 3.8 degrees. Conclusions. The symmetry ratio algorithm allows automatic measurement of vertebral rotation in idiopathic scoliosis without intraobserver or interobserver error due to landmark point selection.

Incremental benefit of myocardial contrast to combined dipyridamole-exercise stress echocardiography for the assessment of coronary artery disease

Background-Although assessment of myocardial perfusion by myocardial contrast echocardiography (MCE) is feasible, its incremental benefit to stress echocardiography is not well defined. We examined whether the addition of MCE to combined dipyridamole-exercise echocardiography (DExE) provides incremental benefit for evaluation of coronary artery disease (CAD). Methods and Results-MCE was combined with DExE in 85 patients, 70 of whom were undergoing quantitative coronary angiography and 15 patients with a low probability of CAD. MCE was acquired by low-mechanical-index imaging in 3 apical views after acquisition of standard resting and poststress images. Wall motion, left ventricular opacification, and MCE components of the study were interpreted sequentially, blinded to other data. Significant (>50%) stenoses were present in 43 patients and involved 69 coronary territories. The addition of qualitative MCE improved sensitivity for the detection of CAD (91% versus 74%, P=0.02) and accurate recognition of disease extent (87% versus 65% of territories, P=0.003), with a nonsignificant reduction in specificity. Conclusions-The addition of low-mechanical-index MCE to standard imaging during DExE improves detection of CAD and enables a more accurate determination of disease extent.

3-D magnetic resonance angiography versus conventional angiography in peripheral arterial disease: Pilot study

Angiography is usually performed as the preoperative road map for those requiring revascularization for lower extremity peripheral arterial disease (PAD). The alternative investigations are ultrasound, 3-D magnetic resonance angiography (3-D MRA) and computed tomography angiography. This pilot study aimed to assess whether 3-D MRA could replace the gold standard angiography in preoperative planning. Eight patients considered for aortoiliac or infrainguinal arterial bypass surgery were recruited. All underwent both imaging modalities within 7 days. A vascular surgeon and a radiologist each reported on the images from both the 3-D MRA and the angiography, with blinding to patient details and each others reports. Comparisons were made between the reports for the angiographic and the 3-D MRA images, and between the reports of the vascular surgeon and the radiologist. Compared to the gold standard angiogram, 3-D MRA had a sensitivity of 77% and specificity of 94% in detecting occlusion, and a sensitivity of 72% and specificity of 90% in differentiating high grade (> 50%) versus low grade (< 50%) stenoses. There was an overall concordance of 78% between the two investigations with a range of 62% in the peroneal artery to 94% in the aorta. 3-D MRA showed flow in 23% of cases where conventional angiography showed no flow. In the present pilot study, 3-D MRA had reasonable concordance with the gold standard angiography, depending on the level of the lesion. At times it showed vessel flow where occlusion was shown on conventional angiogram. 3-D MRA in peripheral vascular disease is challenging the gold standard, but is inconsistent at present.

Acute appendagitis: emergency presentation and computed tomographic appearances

Acute epiploic appendagitis is an uncommon cause of abdominal pain. It is caused by torsion of an epiploic appendage or spontaneous venous thrombosis of a draining appendageal vein.1 The diagnosis of this condition primarily relies on cross-sectional imaging and is made most often after computed tomography (CT). Clinically, it is most often mistaken for acute diverticulitis. Approximately 7.1% of patients investigated to exclude sigmoid diverticulitis have imaging findings of primary epiploic appendagitis.

Imaging features of ocular adnexal lymphoproliferative disease

Purpose To evaluate the imaging characteristics of a cohort of patients with ocular adnexal lymphoproliferative disease (OALD). Methods A noncomparative retrospective review between 1992 and 1995 and prospective study from 1995 to 2005 of the clinical, imaging and treatment of 105 patients presenting to tertiary orbital referral centre presenting with OALD. Results One hundred and five patients (mean age 61 years, range 11-90 years) with equal gender distribution were included. Fifty-three were primary and 52 were secondary. Computed tomography (CT) usually showed a well-circumscribed lesion of greater than brain density, moulding to adjacent tissues with moderate enhancement. Aggressive histology was associated with bone destruction, while moulding was associated with indolent histology (P < 0.005). MRI in OALD showed intermediate signal intensity on T1- and T2-weighted images and moderate enhancement with gadolinium. Gallium scanning sensitivity to detect ocular adnexal disease was 25 and 57% for systemic involvement. Positron emission tomography (PET) upstaged (71%) of patients with systemic lymphoproliferative involvement, having a higher sensitivity than CT in detecting distant disease (86 vs 72%). Conclusions CT and/ or MRI are essential in the evaluation of OALD and can be used to establish that an orbital lesion may be lymphoprolifetaive in nature. Further, these imaging modalities may predict the behaviour of the lymphoma in certain cases. Gallium scanning provides no additional information to CT and does not influence patient treatment. PET represents an important addition to the assessment of OALD with real impact on patient management.

Stage is not a reliable indicator of tumor volume in non-small cell lung cancer: a preliminary analysis of the trans-tasman radiation oncology group 99-05 database

Background: Tumor volume has been shown to be a prognostic factor for the response of some tumors to radiotherapy. TNM stage has prognostic value for patients treated surgically for non-small cell lung cancer (NSCLC), but its value is less clear for patients treated by nonsurgical means. This may be because tumor size is not a consistent determinant of T stage or stage group. As part of the preliminary analyses for the Trans-Tasman Radiation Oncology Group 99-05 study, the authors performed this analysis to determine to what extent stage reflects tumor volume. Methods: In this prospective multicenter observational study, patients had to have histologically proven NSCLC, no evidence of disease beyond the primary site or thoracic lymph nodes, and been planned for radical radiotherapy with or without chemotherapy. Tumor volume measurements were based on computed tomography-based treatment planning images. Results: Four hundred four patients were available for analysis. There was a strong correlation between (log) maximum tumor diameter and (log) tumor volume (r = 0.93, p < 0.001). Although there was a highly significant trend of increasing volume with increasing T stage and stage group, when tumors were categorized into four groups according to increasing volume, there was only 55% concordance with T stage and 67% concordance with stage group. Conclusions: There is limited correlation between tumor size and disease stage in patients with NSCLC. This justifies documentation and investigation of size as a potential prognostic factor independent of stage. Maximum tumor diameter may be an adequate substitute for volume as a measurement of size.