Diagnostic accuracy of high-definition CT coronary angiography in high-risk patients

AIM

To assess the diagnostic accuracy of computed tomography coronary angiography (CTCA) using a combination of high-definition CT (HD-CTCA) and high level of reader experience, with invasive coronary angiography (ICA) as the reference standard, in high-risk patients for the investigation of coronary artery disease (CAD).

MATERIALS AND METHODS

Three hundred high-risk patients underwent HD-CTCA and ICA. Independent experts evaluated the images for the presence of significant CAD, defined primarily as the presence of moderate (≥ 50%) stenosis and secondarily as the presence of severe (≥ 70%) stenosis in at least one coronary segment, in a blinded fashion. HD-CTCA was compared to ICA as the reference standard.

RESULTS

No patients were excluded. Two hundred and six patients (69%) had moderate and 178 (59%) had severe stenosis in at least one vessel at ICA. The sensitivity, specificity, positive predictive value, and negative predictive value were 97.1%, 97.9%, 99% and 93.9% for moderate stenosis, and 98.9%, 93.4%, 95.7% and 98.3%, for severe stenosis, on a per-patient basis.

CONCLUSION

The combination of HD-CTCA and experienced readers applied to a high-risk population, results in high diagnostic accuracy comparable to ICA. Modern generation CT systems in experienced hands might be considered for an expanded role.

The role of multidetector computed tomography coronary angiography in imaging complications post-cardiac surgery

There have been numerous advances in the field of cardiac imaging. The advent of multidetector computed tomography coronary angiography (MDCT-CA) and in particular electrocardiographic (ECG)-gated acquisition has revolutionized the investigation of the complete spectrum of complications of common cardiothoracic surgical procedures. Generic complications, such as mediastinitis, pericardial effusion, sternal osteomyelitis, and mediastinal fibrosis, are discussed with illustrative examples of multiplanar and volume-rendered three-dimensional reconstructions. Graft-related complications of both coronary artery bypass grafts and aortic root grafts are reviewed. The role of MDCT-CA in the investigation of prosthetic valve endocarditis and root abscesses is outlined. We present a complete illustration of the detailed images that are obtained when investigating a full range of graft-related complications from both aortic and coronary surgery using ECG-gated MDCT-CA. MDCT-CA has the potential to become established as the optimal technique with which to image a multitude of complications post-cardiac surgery.

Pulmonary venous evaluation using electrocardiogram-gated 64-detector row cardiac CT

OBJECTIVES

Radiofrequency ablation of the pulmonary veins is an accepted treatment for atrial fibrillation. An accurate knowledge of pulmonary venous anatomy and dimensions is desirable prior to such a procedure. The objective of this study was to use 64-detector row cardiac CT to investigate the changes in pulmonary venous dimensions during the cardiac cycle.

METHODS

Data from 44 consecutive patients with no significant cardiovascular pathology who underwent electrocardiogram (ECG)-gated 64-detector row coronary angiography were retrospectively analysed. Average diameter and cross-sectional area were measured at 5 mm intervals from each pulmonary vein ostium, in ventricular end-diastole and ventricular end-systole, using curved multiplanar reformats.

RESULTS

4 (9.1%) patients had pulmonary vein anomalies and were excluded. In the remaining 40 patients, pulmonary vein diameter and area at the ostium were significantly larger in end-systole in all four veins, with the largest differences in the superior pulmonary veins. Dimensional changes for diameter (millimetres) and area (square millimetres) were as follows: left superior pulmonary vein, 2.5 (p<0.001), 65.48 (p<0.001); right superior pulmonary vein, 1.63 (p<0.001), 56.27 (p<0.001); left inferior pulmonary vein, 1.1 (p<0.001), 30.41 (p<0.001); and right inferior pulmonary vein, 0.68 (p=0.005), 30.14 (p=0.005). Less marked changes were seen at measurement sites further from the atrium. Interobserver correlation was high (all but one measurement >0.9).

CONCLUSION

Pulmonary vein dimensions change significantly between end-systole and end-diastole, and the ostia of the superior pulmonary veins are potentially the most vulnerable to dimensional inaccuracies. ECG-gated cardiac CT may provide a more precise method of pulmonary venous dimensional measurement than non-gated techniques. Knowledge of change in pulmonary vein diameter offers interesting potential research into the effect of pulmonary vein function.

Imaging of illicit drug use

Illicit drug abuse is a continuing menace of epidemic proportions associated with serious medical and social problems. Drug abuse can have a wide variety of presentations some of which can be life-threatening. The clinical diagnosis can be challenging as the history is usually limited or absent. Radiologists need to be familiar with varied imaging presentations and the related complications of illicit drug abuse to ensure correct diagnosis and appropriate timely treatment. This review will illustrate the imaging spectrum of illicit drug abuse involving several organ systems and also discuss the pathophysiological consequences of drug abuse.

Imaging the pericardium: appearances on ECG-gated 64-detector row cardiac computed tomography

Multidetector row computed tomography (MDCT) with its high spatial and temporal resolution has now become an established and complementary method for cardiac imaging. It can now be used reliably to exclude significant coronary artery disease and delineate complex coronary artery anomalies, and has become a valuable problem-solving tool. Our experience with MDCT imaging suggests that it is clinically useful for imaging the pericardium. It is important to be aware of the normal anatomy of the pericardium and not mistake normal variations for pathology. The pericardial recesses are visible in up to 44% of non-electrocardiogram (ECG)-gated MDCT images. Abnormalities of the pericardium can now be identified with increasing certainty on 64-detector row CT; they may be the key to diagnosis and therefore must not be overlooked. This educational review of the pericardium will cover different imaging techniques, with a significant emphasis on MDCT. We have a large research and clinical experience of ECG-gated cardiac CT and will demonstrate examples of pericardial recesses, their variations and a wide variety of pericardial abnormalities and systemic conditions affecting the pericardium. We give a brief relevant background of the conditions and reinforce the key imaging features. We aim to provide a pictorial demonstration of the wide variety of abnormalities of the pericardium and the pitfalls in the diagnosis of pericardial disease.

Prognostic value of coronary multidetector CT angiography in patients with an intermediate probability of significant coronary heart disease

The aim of this study was to determine the prognostic value of coronary multidetector CT angiography (MDCTA) in patients with an intermediate pre-test probability of significant coronary artery disease (CAD). Patients who underwent 64-slice coronary MDCTA and met the selection criteria were identified and assessed for intermediate pre-test probability. Coronary MDCTA scans were preceded by calcium scoring, whereas all MDCTA scans were interrogated for the presence of plaque composition and the distribution and degree of stenosis. Significant stenosis was classified as being >50% of the luminal diameter. All patients were followed up for the occurrence of (i) cardiac death, (ii) non-fatal myocardial infarction, (iii) unstable angina requiring hospital admission and (iv) revascularisation. 138 patients were included (follow-up of 19.9 months); of these, 8 had a cardiac event (all revascularisations) and all had a positive coronary MDCTA. Patients with normal coronary arteries or non-significant stenosis suffered no cardiac events during follow-up. There were significant differences between the two groups regarding the presence of significant stenosis (p<0.001), the presence of plaque (p = 0.011) and a calcium score >10 (p = 0.003); 36.4% of patients with significant stenosis underwent revascularisation. In conclusion, this is the first UK study to investigate survival data in a population of intermediate-risk patients with no prior history of CAD who were investigated with coronary MDCTA. Coronary MDCTA can confidently rule out significant CAD in the intermediate-risk population and guide risk factor modification in patients with demonstrated coronary atheroma.

Imaging the heart valves using ECG-gated 64-detector row cardiac CT

Multi-detector row cardiac CT imaging demonstrates clinical usefulness in valvular heart disease, for which CT has not been traditionally used. Electrocardiographic (ECG)-gated CT coronary angiography also has an established clinical role with an increasingly solid evidence base, and the same data set in these patients also provides valuable information about chamber and valvular structure and function; this information should also be considered when interpreting cardiac CT and non-ECG gated thoracic imaging. Although true flow data cannot be achieved using CT, as with echocardiography and MRI, there are a number of imaging features that may be used when interpreting and inferring valve pathology. This article discusses the role of currently available imaging modalities and the rationale for cardiac CT, while focusing on the CT interpretation of valvular heart disease with respect to the relevant pathophysiology and management options that have importance to the radiologist. A suggested method of post-processing image review is provided with reference to a variety of normal and pathological pictorial illustrations.

Multi-detector row CT coronary angiography in patients with cardiomyopathy -- initial single-centre experience

AIMS

To evaluate the diagnostic accuracy of computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients with cardiomyopathy (CM).

SUBJECTS AND METHODS

Eighteen patients with CM were approached to undergo CT coronary angiography to evaluate the use of this technique for investigating the presence of significant coronary artery disease (CAD), and also to compare the findings with catheter angiography.

RESULTS

On a segment-by-segment analysis the sensitivity, specificity, positive and negative predictive values in the CM group were 66.7, 96.5, 40 and 98.8%, respectively, with 100% accuracy in "whole-patient terms".

CONCLUSION

Non-invasive, 16-detector row CT coronary angiography in patients with presumed CM would seem to be a useful clinical tool for the exclusion of significant coronary artery disease. However, the presence of suboptimal contrast opacification in this patient group means that the implication of these results must be interpreted with caution.

Giant coronary artery aneurysm secondary to Kawasaki disease: diagnosis in an adult by multi-detector row CT coronary angiography

We present the case of an adult female patient with a giant coronary artery aneurysm secondary to Kawasaki disease diagnosed for the first time, as far as the authors are aware, on multi-detector row computed tomography (MDCT). The long-term complications relate to the persistence of these aneurysms with giant coronary aneurysms having the lowest regression rate, the highest risk of stenosis and strongest association with myocardial infarction. MDCT coronary angiography represents an ideal, alternative non-invasive imaging modality for the diagnosis and follow-up of the coronary arterial complications of Kawasaki disease, thereby avoiding invasive coronary imaging, and its use in the management algorithm should be considered. We also aim to contribute to the expanding clinical role of MDCT coronary imaging.

16-Detector row computed tomographic coronary angiography in patients undergoing evaluation for aortic valve replacement: comparison with catheter angiography

AIM

To evaluate the diagnostic accuracy of 16-detector row computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients under evaluation for aortic stenosis pre-aortic valve replacement.

SUBJECTS AND METHODS

Forty consecutive patients under evaluation for severe aortic stenosis and listed for cardiac catheterization before potential aortic valve replacement underwent coronary artery calcium (CAC) scoring and retrospective electrocardiogram (ECG)-gated multi-detector row computed tomographic coronary angiography (MDCTA) using a GE Lightspeed 16-detector row CT within 1 month of invasive coronary angiography (ICA) for comparative purposes. All 13 major coronary artery segments of the American Heart Association model were evaluated for the presence of > or =50% stenosis and compared to the reference standard. Data were analysed on a segment-by-segment basis and also in "whole patient" terms.

RESULTS

A total of 412/450 segments from 35 patients were suitable for analysis. The overall accuracy of MDCTA for detection of segments with > or =50% stenosis was high, with a sensitivity of 81.3%, specificity 95.0%, positive predictive value (PPV) 57.8%, and negative predictive value (NPV) 98.4%. On a "whole-patient" basis, 100% (19/19) of patients with significant coronary disease were correctly identified and there were no false-negatives. Excluding patients with CAC >1000 from the analysis improved the accuracy of MDCTA to: sensitivity 90%, specificity 98.1%, PPV 60%, NPV 99.7%.

CONCLUSION

Non-invasive 16-detector row MDCTA accurately excludes significant coronary disease in patients with severe aortic stenosis undergoing evaluation before aortic valve replacement and in whom ICA can therefore be avoided. Its segment-by-segment accuracy is improved further if CAC>1000 is used as a gatekeeper to MDCTA.

Multidetector row computed tomography: imaging congenital coronary artery anomalies in adults

The quality of the imaging of the main coronary arteries and side branches provided by multidetector row computed tomography (MDCT) may have importance when assessing congenital coronary artery anomalies. This review discusses the rationale for using MDCT for this indication and examines the advantages and disadvantages of the technique. Examples of MDCT imaging of congenital coronary artery anomalies are presented. These images provide persuasive evidence to support clinical use of MDCT cardiac imaging in the context of suspected congenital coronary artery anomalies as a first line investigation.

Multi-detector row computed tomography: imaging in acute aortic syndrome

Acute aortic syndromes (AAS) encompass a spectrum of emergencies. These include those non-traumatic disease entities of the aorta namely, penetrating atherosclerotic ulcer, intramural haematoma, dissection and aneurysm rupture. The various types of AAS cannot be reliably differentiated on clinical grounds alone. Acute thoracic aortic injury is usually included in this group even though clinical presentation is different, i.e., in the context of trauma, the imaging features are very similar. Differentiation of AAS from acute coronary syndrome (ACS) is important, however, it must be remembered that ACS may occur as a result of AAS. Now electrocardiogram (ECG)-gating technology is widely available, ECG-gated multi-detector row computed tomography (MDCT) is a powerful clinical tool in the acute emergency setting, which enables rapid and specific diagnosis of aortic pathology. ECG-gated MDCT significantly reduces motion artefact, avoids potential pitfalls in diagnosis and often provides diagnostic information about the coronary arteries. It should be used as a first-line imaging technique. This article examines the role of MDCT imaging and cardiac gating in the assessment of AAS and discusses the differentiation of this spectrum of aortic diseases with reference to the key imaging findings as obtained by experience in our institution.

Efficacy and complications of Angioseal in antegrade puncture

AIM

Although arterial closure devices are in use for over a decade, there have been no specific study to assess the use of the same in antegrade puncture.

MATERIAL AND METHOD

Consecutive patients undergoing antegrade puncture for peripheral vascular disease in a single centre performed by a single operator were included in this study. The notes and the angiograms were reviewed retrospectively for possible complications and the severity of disease.

RESULT

Over a 25-month period, 21 patients with antegrade puncture had Angioseal deployed for haemostasis. Post-procedure complications recorded from the case notes showed one episode of haematoma formation and one case of worsening ischaemia. The severity of the disease at the puncture site did not influence the outcome.

CONCLUSION

Use of Angioseal is safe and effective in antegrade punctures for peripheral vascular disease. The result is independent of the severity of disease at the puncture site.

Multi-detector row computed tomography: imaging the coronary arteries

Over the last 2 years, multi-detector row computed tomographic (MDCT) cardiac imaging has continued to rapidly develop and evolve from the experimental research setting to become a useful clinical tool. The increasing availability of MDCT presents today's clinicians with an additional non-invasive diagnostic cardiac imaging method, in particular for the coronary arteries. With the advent and increasing clinical use of 16-detector row machines, and now with the imminent clinical emergence of 64-channel machines, the improvements in spatial and temporal resolution and sophisticated ECG-gating are allowing motion-free, fast, accurate, detailed, contrast-enhanced cardiac imaging that begins to approach the accuracy of traditional invasive diagnostic techniques. Additional diagnostic information may also be provided.

Highly accurate coronary angiography with submillimetre, 16 slice computed tomography

OBJECTIVE

To assess submillimetre coronary computed tomographic angiography (CTA) in comparison with invasive quantitative coronary angiography as the gold standard and to examine the effect of significant coronary artery calcification (CAC), which is known to impede lumen visualisation, on the accuracy of the examination.

METHODS

After invasive coronary angiography, 58 patients underwent coronary imaging with a GE Lightspeed 16 computed tomography (CT) system. CAC was quantified after an ECG triggered acquisition with a low tube current. Coronary CTA was performed with retrospective ECG gating and a 16 x 0.63 mm collimation and was reconstructed with an effective 65-250 ms temporal resolution. All 13 major coronary artery segments were evaluated for the presence of > or = 50% stenosis, and compared with the gold standard.

RESULTS

One patient moved and could not be evaluated. All segments (except occluded segments) were evaluated for 57 patients. Overall the accuracy of coronary CTA for detection of > or = 50% stenosis was: sensitivity 83%, specificity 97%, positive predictive value 80%, and negative predictive value 97%. The number of diseased coronary arteries was correctly diagnosed in 34 of 38 (89%) patients overall. Altogether 21 of 57 (37%) patients had a CAC score > or = 400, which was predefined as representing significant CAC. Excluding these patients from the analysis improved the accuracy of coronary CTA to a sensitivity of 89%, specificity 98%, positive predictive value 79%, and negative predictive value 99%.

CONCLUSIONS

Non-invasive coronary angiography with submillimetre CT is reliable and accurate. It appears that a subgroup of patients may be selected based on CAC score in whom the investigation has even higher accuracy. Coronary CTA has reached the stage where it should be considered for a clinical role. Further research is required to define this role.

A comparison of a 'J' wire and a straight wire in successful antegrade cannulation of the superficial femoral artery

AIMS

To evaluate the success of two different types of wire in common use in their ability to successfully cannulate the superficial femoral artery (SFA) using antegrade puncture.

METHODS

50 consecutive patients in whom antegrade infra-inguinal intervention was planned, underwent common femoral arterial puncture and then cannulation with either a standard 3mm 'J' wire or a floppy tipped straight wire (William Cook-Europe). The frequency with which each type of wire entered the SFA or profunda femoris artery without image guidance was recorded. Further analysis was also made of the success of manipulation of the wire into the SFA following profunda cannulation and the use of alternative guide wires.

RESULTS

In 19 out of 25 (76%) patients the 'J' wire correctly entered the SFA without image guidance. Only 5 out of 25 (25%) of straight wires entered the SFA with the initial pass (p < 0.0001). Following further manipulation with the same wire all except 1 'J' wire was successfully negotiated into the SFA. The same was true for only 9 of the remaining straight wires with 11 patients requiring an alternative guide wire.

CONCLUSIONS

When performing antegrade cannulation of the SFA a 'J' wire is more likely to be successful than a straight guide wire.

Multidetector row CT angiography of the lower limb arteries: a prospective comparison of volume-rendered techniques and intra-arterial digital subtraction angiography

AIM

To assess whether multi-detector CT angiograms (MDCTA) of the lower limb arteries, compared with conventional digital subtraction angiograms (DSA), could replace invasive arteriography in patients with symptomatic peripheral arterial disease.

MATERIALS AND METHODS

In a prospective comparative analysis of MDCTA and DSA in 44 patients, MDCTA was analyzed using volume-rendered images acquired at a workstation and viewed in tandem with the original axial data. Designated arterial segments were graded according to their degree of stenosis.

RESULTS

We found agreement for the degree of stenosis in 88.8% and 85.4% of 1024 segments analysed for two observers. The sensitivity for treatable lesions (>50% stenosis) was 79.1% and 72% with a specificity of 93.3% and 92.6%. DSA failed to visualize 7.3% of segments that were visible with MDCTA. These segments were exclusively downstream to long segment occlusions.

CONCLUSION

MDCTA using 4-slice machines is insensitive to detecting significant arterial stenoses in the lower limb arteries. MDCTA is superior to DSA in its visualization of arterial territories downstream to significant occlusive disease.

The Effect of Reporting Speed on Plain Film Reporting Errors

AIM

To determine whether reporting plain films at faster rates lead to a deterioration in accuracy.

METHODS

Fourteen consultant radiologists were asked to report a total of 90 radiographs in three sets of 30. They reported the first set at the rate they would report normally and the subsequent two sets in two thirds and one half of the original time. The 90 radiographs were the same for each radiologist, however, the order was randomly generated for each.

RESULTS

There was no significant difference in overall accuracy for each of the three film sets (p=0.74). Additionally no significant difference in the total number of false-negatives for each film set was detected (p=0.14). However, there was a significant decrease in the number of false-positive reports when the radiologists were asked to report at higher speeds (p=0.003).

CONCLUSIONS

When reporting accident and emergency radiographs increasing reporting speed has no overall effect upon accuracy, however, it does lead to less false-positive reports.

Three dimensional volume quantification of aortic valve calcification using multislice computed tomography

OBJECTIVE

To assess a new multislice computed tomography (CT) technique for three dimensional quantification of aortic valve calcification volume (3D AVCV) and to study the relation between stenosis and calcification of the aortic valve.

METHODS

50 patients with echocardiographic calcification of the aortic valve underwent two separate ECG triggered multislice CT for quantification of 3D AVCV. The agreement between the two 3D AVCV scores was assessed and 3D AVCV was compared with echocardiographic markers of severity of aortic stenosis.

RESULTS

Overall the level of agreement between the two 3D AVCV scores was excellent (median interscan variability 7.9% (interquartile range 10.1); correlation coefficient, r = 0.99; repeatability coefficient 237.8 mm3 (limits of agreement -393 to 559 mm3)). However, the magnitude of the 3D AVCV did influence the interscan variability. The 3D AVCV correlated closely with the maximal predicted transvalvar gradient (r2 = 0.77) and aortic valve area (r2 = 0.73).

CONCLUSIONS

Multislice CT provides a technique for quantifying 3D AVCV that has good reproducibility. There is a close non-linear relation between echocardiographic parameters of severity of valve stenosis and 3D AVCV scores.

Refined computed tomography of the thoracic aorta: the impact of electrocardiographic assistance

There have been a number of advances in helical computed tomography (CT) in recent years, which have had a beneficial impact on the quality of imaging of the thoracic aorta. These advances include sub-second gantry rotation, multislice acquisition, and the use of electrocardiographic (ECG) assistance. We examine these techniques with emphasis on the principles behind ECG assistance and its use to reduce aortic motion artefact. We highlight examples of ECG-assisted multislice CT in a spectrum of pathologies of the thoracic aorta.

Multislice computed tomographic coronary angiography: experience in a UK centre

AIM

To evaluate the technique of coronary angiography with retrospectively electrocardiogram (ECG)-gated four-slice helical computed tomography (CT).

MATERIALS AND METHODS

Within 1 month of undergoing routine day-case diagnostic coronary angiography, 30 consecutive patients also underwent retrospectively ECG-gated multislice CT coronary angiography. This enabled direct comparison of seven segments of proximal and mid-coronary artery for each patient by two blinded assessors. Each segment of coronary artery from the multislice CT image was evaluated initially for "assessability" and those segments deemed assessable were subsequently investigated for the presence or absence of a significantly (n=70%) stenotic lesion.

RESULTS

Overall 68% of proximal and mid-coronary artery segments were assessable. The sensitivity and specificity of four-slice CT coronary angiography in assessable segments for detecting the presence or absence (n=70%) of stenoses were 72 and 86%, respectively. These results correspond to a positive predictive value of 53% and a 93% negative predictive value. If the 32% of non-assessable segments are added into the calculation then the sensitivity and specificity fall to 49 and 66%, respectively.

CONCLUSION

Although multislice CT coronary angiography is a promising technique, the overall assessability and diagnostic accuracy of four-slice CT acquisition is not sufficient to justify routine clinical use. Further, evaluation should investigate the benefit of the reduction in temporal and spatial resolution offered by 16 and 32 slice acquisition.

Multislice computed tomography cardiac imaging: current status

Non-invasive CT coronary artery imaging has previously had little relevance to most UK radiologists due to the limited availability of electron beam CT scanners. Major advances in CT technology have promoted new applications for helical CT, which include cardiac imaging. Widespread installation of 'multislice' helical CT scanners will make CT coronary artery imaging available for the first time in many UK hospitals. The technical advances and early clinical trial data are reviewed and multislice helical CT cardiac imaging in general is discussed.

The in vitro and in vivo ultrasonographic appearances of the angio-seal percutaneous closure device

PURPOSE

To assess the ultrasound appearances of the Angio-Seal device in an animal model and in twenty patients following catheterization of the femoral artery.

MATERIALS AND METHODS

Ten patients were scanned within 8 hours of their procedure (early group) and 10 at two to four days (delayed group) using Acuson Aspen and Sequoia scanners. Colour flow images were taken and Doppler spectral analysis was performed proximal proximal to, at and distal to the Angio-Seal device. Early and delayed in vitro images were taken in a water bath in which the Angio-Seal device was deployed across a normal porcine aorta for comparison.

RESULT

In the ten early patients colour and Doppler drop out were seen in 100 percent and 90 percent respectively compared with 90 percent and 60 percent in the delayed group. The device was seen in 30 percent and 90 percent in early and delayed groups respectively. In the in vitro study the components of the device were seen and a posterior acustic shadow noted. This shadow was less obvious and the polymer anchor more easily seen in the delayed group.

CONCLUSION

The Angio-Seal device produces a consistent artifact when scanned soon after deployment. These appearances could potentially be mistaken for a vascular occlusion by the unwary in the appropriate clinical setting of acute post catheterisation lower limb ischaemia however an awareness of the normal sonographic appearances of this device would make this misinterpretation unlikely.

Urgent contrast enhanced computed tomography in the diagnosis of acute bowel infarction

Bowel infarction commonly presents as an acute abdomen that rapidly progresses to severe shock. The diagnosis is often not clinically suspected. Three cases are described where the diagnosis was made during dynamic contrast enhanced computed tomography (CT), when gas was demonstrated in the portal venous system and liver. Two patients died during surgery, the third survived because of the prompt diagnosis made on CT, and subsequent surgical treatment. The radiological findings are reviewed.

Aortic valve imaging with computed tomography: a review

The finding of aortic valve calcification is of clinical relevance. Thickening and calcification of the aortic valve ('aortic sclerosis') may progress over time to calcific aortic stenosis, and calcification of the aortic valve has prognostic importance even in the absence of valve obstruction. Aortic valve calcification may also have effects on the conduction system. There is progressive awareness of the need for an imaging technique that can accurately and reproducibly quantify calcification of native and prosthetic aortic valves. Through adaptation of techniques from electron beam computed tomography (CT) coronary calcium scoring, CT has been proposed as the appropriate imaging modality. Although originally described as a method of comparing the calcification of different aortic valve bioprostheses, the major role suggested for CT aortic valve calcium quantification is now in the field of preventive medicine. This has stemmed from the recognition that traditional vascular risk factors also have a role in the etiology of calcific aortic stenosis. Subsequently, the realization that pharmacological modification of lipid profiles may result in slowing of progression or even regression of aortic valve calcification has led to a need to quantify aortic valve calcification for follow up purposes. Echocardiography has been used to estimate aortic valve calcification in studies of the natural history of aortic stenosis, but it does not accurately quantify calcium. CT appears able to fulfil this requirement, though the technique is still relatively novel. This review examines the need for aortic valve calcium quantification and the evolution of imaging to the current status. Future directions and the promise of new helical CT technologies with respect to cardiac imaging are explored.

Azygos reflux: a CT sign of cardiac tamponade

Three patients who were investigated with dynamic contrast medium enhanced computed tomography (CT) of the thorax were noted to have pericardial effusions with reflux of contrast medium back along the azygos vein. The diagnosis of cardiac tamponade was not made clinically, but in each case was suggested from the CT findings. Confirmation of the diagnosis was made in all three cases, two patients with echocardiography and one at post mortem. One patient made a rapid recovery following the insertion of a pericardial drain, another made a temporary recovery after pericardiocentesis but the third died. Thirty CT scans performed with similar protocol were reviewed and none of these demonstrated reflux along the azygos vein. The presence of contrast medium refluxing into the azygos vein implies significant haemodynamic disturbance, and in the presence of a pericardial effusion suggests the diagnosis of cardiac tamponade.

Long-term follow-up of the antheor inferior vena cava filter

The first long-term follow-up of the use of the Antheor inferior vena cava (IVC) filter is presented. Between December 1994 and December 1996, 20 Antheor IVC filters were inserted. Seven patients subsequently died and of the 13 patients remaining alive, 11 were available for long-term follow-up. One death was due to migration of the filter to the main pulmonary artery 6 weeks after insertion and because of this case, and other similar reports, the filter has now been withdrawn from clinical use. Of the 11 filters assessed at follow-up, three were fractured. One filter contained thrombus and one IVC was occluded. Our experience highlights the problem of central migration, but also shows a high incidence of filter fracture which has not previously been described with this design of filter.

Conservative management of gastric rupture following scuba diving

Gastric rupture is an uncommon surgical problem which normally presents with an acute abdomen and peritonism. An unusual case following underwater ascent and its conservative management is presented.