Dose and image quality comparison between prospectively gated axial and retrospectively gated helical coronary CT angiography

Objective

Our aim was to compare image quality, coronary segment assessability and radiation dose in prospectively gated axial (PGA) coronary CT angiography (CTA) and conventional retrospectively gated helical (RGH) coronary CTA.

Methods

Institutional review committee approval and informed consent were obtained. RGH CTA was performed in 41 consecutive patients (33 males, 8 females; mean age 52.6 years), then the PGA CTA technique was evaluated in 41 additional patients (24 males, 17 females; mean age 57.3 years) all with a pre-scan heart rate of ≤70 beats per minute (bpm). Two radiologists, blinded to clinical information, independently scored subjective image quality on a five-point ordinal scale.

Results

The mean effective dose in the PGA group was 4.7±0.9 mSv, representing a 69% dose reduction compared with the RGH CTA group (15.1±1.9 mSv, p<0.001). The mean segmental image quality score was significantly higher in the PGA group (3.4 vs 3.2) than in the RGH CTA group (p<0.005). The percentage of assessable segments was 98.1% in the PGA group and 97.3% in the RGH group (p = 0.610).

Conclusion

PGA CTA offers a significant reduction in radiation dose compared with RGH CTA, with comparable image quality for patients with heart rates below 70 bpm.Rapid advances in multidetector CT (MDCT) technology have enabled non-invasive coronary angiography with high diagnostic accuracy [1–4]. However, the potential radiation risks associated with standard retrospectively gated helical (RGH) techniques for MDCT-based coronary CT angiography (CTA) have become a concern [5, 6]. Reported radiation doses from coronary CTA have ranged from 11 to 27 mSv [1, 7–10]: nearly 2–4 times the radiation dose attributed to typical invasive diagnostic angiography [11, 12]. Consequently, reducing cardiac CT doses to levels as low as reasonably achievable has become a major issue. A new prospectively gated axial (PGA) acquisition protocol has recently been introduced [13] to reduce the radiation dose by scanning only the mid-diastolic phase [8–10] of the cardiac cycle. The acquisition is based on a prospective electrocardiogram (ECG)-triggered sequential axial acquisition mode in opposition to the standard retrospectively gated continuous helical acquisition. Our aim was to compare image quality and radiation dose of PGA-based coronary CTA with the standard helical mode on a 64-channel CT.     

320-detector row CT coronary angiography: effects of heart rate and heart rate variability on image quality, diagnostic accuracy and radiation exposure

Objectives

To evaluate the effects of heart rate and heart rate variability on image quality, patient dose and diagnostic accuracy of 320-detector row CT.

Methods

94 patients were prospectively enrolled. Heart rate was defined as the mean value of different intervals elapsing between two consecutive R waves in an electrocardiogram (R–R intervals) and the heart rate variability was calculated as the standard deviation from the average heart rate. The image quality was evaluated by four grades, according to motion artefacts (“step artefacts” and “blurring artefacts”). The diagnostic accuracy was analysed in 43 patients who were scheduled for invasive coronary angiography (ICA). The coeffects of heart rate and heart rate variability on image quality, radiation dose and diagnostic accuracy were evaluated by multivariate regression.

Results

The mean image quality score was 1.2±0.5 and the mean effective dose was 14.8±9.8 mSv. The results showed that heart rate (74.0±11.2 beats per minute) was the single factor influencing image quality (p<0.001) and radiation dose (p<0.001), while heart rate variability (3.7±4.6) had no significant effect on them (p=0.16 and p=0.47, respectively). For 43 patients who underwent ICA, heart rate and heart rate variability showed no influence on the accuracy (p=0.17 and p=0.12, respectively). Overall sensitivity was 97.4% (37/38), specificity was 99.4% (351/353), positive predictive value was 94.9% (37/39) and negative predictive value was 99.7% (351/352).

Conclusion

320-detector row CT, with improved longitudinal coverage of detector, resolves step artefact and high patient dose caused by irregular heart rate. However, it is still recommended to control heart rate to a lower level to eliminate blurring artefact and radiation dose.As the clinical application of 4-detector CT to scan the coronary arteries by a non-invasive procedure, CT coronary angiography has emerged as an attractive, diagnostic modality for detecting coronary artery disease. However, motion artefact by rapid movement throughout the cardiac cycle and blooming artefact caused by calcified plaque represent the major challenges for artefact-free coronary CT angiography. Generally, “step artefacts” and “blurring artefacts” are two kinds of motion artefact influencing the quality of coronary artery image. To improve image quality, CT scanners with higher spatial resolution, temporal resolution and wider detector array were developed.The Discovery™ CT750 HD (GE Healthcare, Waukesha, WI) improves spatial resolution and decreased calcium blooming artefact significantly [1]. Dual-source CT (DSCT), with two X-ray sources and a temporal resolution of 83 ms, has improved blurring artefacts caused by high heart rate (HR) [2-4]. Nevertheless, as the coverage of the detectors is limited, step artefacts caused by heart rate variability (HRv) is still an inverse factor influencing the image quality [2,3]. Just as the improved temporal resolution should resolve the problem of high HR, the longitudinal coverage of the detector should be expanded further to resolve the influence of HRv [5-8]. 320-detector row dynamic volume CT (DVCT) can cover the whole heart within one heartbeat, which enables DVCT to have the potential to resolve the impact of HRv [9].A previous study has shown that DVCT reliably provides high diagnostic accuracy without HR control [9]. The aim of our study was to evaluate the influence of degree of HR and HRv on image quality, radiation dose and diagnostic accuracy in patients undergoing DVCT.     

320-detector CT coronary angiography with prospective and retrospective electrocardiogram gating in a single heartbeat: comparison of image quality and radiation dose

Objectives

To compare the image quality, radiation dose and diagnostic accuracy of 320-detector CT coronary angiography with prospective and retrospective electrocardiogram (ECG) gating in a single heartbeat.

Methods

Two independent reviewers separately scored image quality of coronary artery segment for 480 cardiac CT studies in a prospective group and a retrospective group (240 patients with a heart rate <65 beats per minute in each group). The two groups matched well for clinical characteristics and CT parameters. There was good agreement for image quality scores of coronary artery segment between the independent reviewers (κ = 0.73). Of the 7023 coronary artery segments, the image quality scores of the prospective group and retrospective group were not significantly different (p>0.05). The mean radiation dose was 10.0±3.5 mSv (range 6.2–21.6 mSv) for prospective ECG gating at 65–85% of R–R interval (the interval between the R-wave of one heartbeat to the R-wave of the next). The mean radiation dose for retrospective ECG-triggered modulated scans was 23.2±3.4 mSv (range 17–27.4 mSv). The mean radiation dose was 57% lower for prospective gating than for retrospective gating (p<0.01).

Results

Compared with coronary angiography, the results for prospective vs retrospective ECG gating were 92% vs 90% for sensitivity (p = 0.23), 89% vs 91% for specificity (p = 0.19), 90% vs 93% for positive predictive value (p = 0.25) and 92% vs 95% for negative predictive value (p = 0.21) for lesions with ≥50% stenosis, respectively.

Conclusion

320-detector CT coronary angiography performed with prospective ECG gating has similar subjective image quality scores, but a 57% lower radiation dose than retrospective ECG gating in a single heartbeat.Cardiovascular disease is the leading cause of morbidity and mortality in the West [1]. Early detection of coronary artery disease (CAD) is of vital importance as timely treatment may significantly reduce morbidity and mortality. Although invasive coronary angiography (CAG) remains the standard of reference for the evaluation of CAD, multidetector CT angiography (CTA) has recently emerged as a robust imaging modality for the non-invasive evaluation of CAD [1-7]. Advances in CTA technology have led to continuous improvements in image quality, as well as a reduction in radiation dose and contrast material [8-10]. Recently, 320-detector CT systems were introduced, with enhanced craniocaudal volume coverage when compared with 64-detector systems. With 16 cm anatomical coverage (0.5 mm×320 detectors), this new generation of CT scanners allows image acquisition of the entire heart within a single gantry rotation and one heartbeat. As detector arrays have evolved to expand coverage in the z-axis, the application of prospective electrocardiogram (ECG) gating has become feasible. Prospective ECG gating protocols with 64-detector systems have been shown to provide a substantial decrease in overall radiation dose to patients, although with some limitations with regard to temporal resolution and artefacts [4]. Dynamic volume 320-detector CT, with full cardiac coverage in one gantry rotation, can now provide prospective ECG gating cardiac images without some of the previous limitations. Specifically, dynamic volume CT provides significant improvements with regard to image quality, temporal uniformity and reduction of artefacts, as well as improvements in patient safety, with a reduction in radiation and contrast doses [6,7,9,10].The image quality, radiation dose and diagnostic accuracy of 320-detector CT with prospective and retrospective ECG gating have not been reported previously. Therefore, the purpose of our study was to compare the image quality, patient radiation dose and diagnostic accuracy of 320-detector CT with prospective and retrospective ECG gating.     

Radiation dose and cancer risk in retrospectively and prospectively ECG-gated coronary angiography using 64-slice multidetector CT

This study aimed to estimate the radiation dose and cancer risk to adults in England, the USA and Hong Kong associated with retrospectively and prospectively electrocardiogram (ECG)-gated coronary computed tomography angiography (CTA) using currently practised protocols in Hong Kong. The doses were simulated using the ImPACT spreadsheet. For retrospectively ECG-gated CTA with pitches of 0.2, 0.22 and 0.24, the effective doses were 27.7, 23.6 and 20.7 mSv, respectively, for males and 23.6, 20.0 and 18.8 mSv, respectively, for females. For prospectively ECG-gated CTA, the effective dose was 3.7 mSv for both males and females. A table of lifetime attributable risks (LAR) of cancer incidence was set up for the English population for the purpose of estimating cancer risk induced by low-dose radiation exposure, as previously reported for US and Hong Kong populations. From the tables, the LAR of cancer incidence for a representative 50-year-old subject was calculated for retrospectively ECG-gated CTA to be 0.112% and 0.227% for English males and females, respectively, 0.103% and 0.228% for US males and females, respectively, and was comparatively higher at 0.137% and 0.370% for Hong Kong males and females, respectively; for prospectively ECG-gated CTA, the corresponding values were calculated to be 0.014% and 0.035% for English males and females, respectively, and 0.013% and 0.036% for US males and females, respectively, and again were higher at 0.017% and 0.060% for Hong Kong males and females, respectively. Our study shows that prospectively ECG-gated CTA reduces radiation dose and cancer risks by up to 87% compared with retrospectively ECG-gated CTA.Conventional coronary angiography is the gold standard for assessing the heart and coronary arteries, owing to its excellent spatial and temporal resolution; however, the procedure is invasive and can cause serious complications, such as thromboembolism and arterial dissection. Non-invasive imaging methods such as computed tomography angiography (CTA) can therefore be advantageous [1–4]. Applications of coronary artery CTA have, in the past, been limited by problems such as cardiac motion, respiratory motion and the small size of coronary arteries. However, technological advances with multidetector CT (MDCT) scanners have enhanced the spatial and temporal resolution achievable by CTA. Moreover, applying electrocardiogram (ECG)-gated technology, the data at diastole during each cardiac cycle can be selected and used for image reconstruction, thereby minimising motion artefacts [5]. There are two kinds of ECG-gating technologies: retrospective ECG gating and prospective ECG gating [5, 6]. For retrospective ECG gating, data are acquired during the entire cardiac cycle and only some of the data (data at the diastolic phase) are used for image reconstruction. To obtain sufficient raw data, data oversampling is used with a low pitch, which, in turn, depends on the patient''s heart rate. For prospective ECG gating, initially the mean duration of a cardiac cycle is averaged over multiple heart cycles. The trigger, a predefined time-point in each subsequent cardiac cycle, is used to initiate a sequential axial scan during diastole. The acquisition time for one axial position is about 250–500 ms. All data acquired in prospectively ECG-gated scans are used for image reconstruction.With the advent of MDCT for coronary CTA, however, radiation dose has become an important issue to be considered [7, 8]. The doses reported from coronary CTA may be even higher than for conventional angiography [9]. Using retrospectively ECG-gated CTA, doses to the organs exposed directly to X-rays are especially high: up to 114 mSv for oesophagus, 80 mSv for breast and 91 mSv for lung [10]. Recently, cancer risks from CTA, the major detriment associated with radiation exposure, have been reported in the literature [10–12]. These studies estimated lifetime cancer incidence to be up to 0.2% and 0.7% for patients undergoing coronary CTA on 16- and 64-slice CT scanners, respectively [10, 12]. Moreover, a lifetime incidence of up to 0.5% and 0.4% was reported specifically for breast and lung cancer, respectively [11]. Doses from prospectively ECG-gated CTA have been reported and were found to be much lower than those for retrospectively ECG-gated CTA [13, 14].This study investigated the radiation dose from retrospectively and prospectively ECG-gated coronary CTA on 64-slice MDCT and compared the associated cancer risk imparted to adults in England, the USA and Hong Kong. Comparisons were based on the principles introduced by the Biological Effects of Ionizing Radiation (BEIR) Committee of the National Research Council in its seventh report (BEIR VII report) [15].     

The effect of adaptive iterative dose reduction on image quality in 320-detector row CT coronary angiography

Objective

To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA).

Methods

50 patients (14 females, mean age 68±9 years) who underwent CTCA (100 kV or 120 kV, 400–580 mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent).

Results

All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4±3.1 HU vs 36.9±4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75±0.38 vs 4.24±0.38; p<0.001).

Conclusion

The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA.CT coronary angiography (CTCA) is a robust non-invasive imaging modality with high spatial and temporal resolution that enables accurate diagnosis or exclusion of coronary artery disease [1-4]. However, CTCA usually exposes the patient to a substantial amount of radiation (9.4–21.4 mSv) [5-7]. Therefore, several scanning techniques, such as ECG-based tube current modulation, prospective ECG triggering and reduced tube voltage scanning, have been developed to reduce the patient''s radiation exposure [6-8]. Reductions of the tube current also lead to lower radiation exposure, as the tube current correlates to dose in a linear fashion. However, lower radiation leads to an increase in CT image noise because the current reconstruction method, filtered back projection (FBP), is unable to consistently generate diagnostic-quality images with reduced tube currents [9].Recently, the adaptive iterative dose reduction technique has been developed as a new reconstruction algorithm to improve image noise [10-12], and has already been shown to reduce the radiation dose in clinical practice [13-16]. Adaptive iterative dose reduction (AIDR) developed for CT by Toshiba Medical Systems Corporation is a modified iterative reconstruction technique in which the original high-noise image undergoes a number of reconstructions that reduce image noise until the resultant image displays the desired noise level. This technique is expected to reduce the radiation dose for a similar noise level to FBP.To our knowledge, no study has evaluated the quality of CT images using AIDR. The purpose of this study was to evaluate the effect of AIDR regarding image noise and image quality in comparison with FBP, using the same raw data set for both FBP and AIDR, in 320-detector row CTCA.     

Adult patient radiation doses from non-cardiac CT examinations: a review of published results

Objectives

CT is a valuable tool in diagnostic radiology but it is also associated with higher patient radiation doses compared with planar radiography. The aim of this article is to review patient dose for the most common types of CT examinations reported during the past 19 years.

Methods

Reported dosimetric quantities were compared with the European diagnostic reference levels (DRLs). Effective doses were assessed with respect to the publication year and scanner technology (i.e. single-slice vs multislice).

Results

Considerable variation of reported values among studies was attributed to variations in both examination protocol and scanner design. Median weighted CT dose index (CTDI_w) and dose length product (DLP) are below the proposed DRLs; however, for individual studies the DRLs are exceeded. Median reported effective doses for the most frequent CT examinations were: head, 1.9 mSv (0.3–8.2 mSv); chest, 7.5 mSv (0.3–26.0 mSv); abdomen, 7.9 mSv (1.4–31.2 mSv); and pelvis, 7.6 mSv (2.5–36.5 mSv).

Conclusion

The introduction of mechanisms for dose reduction resulted in significantly lower patient effective doses for CT examinations of the head, chest and abdomen reported by studies published after 1995. Owing to the limited number of studies reporting patient doses for multislice CT examinations the statistical power to detect differences with single-slice scanners is not yet adequate.The use of CT in medicine is now firmly established and represents one of the most important radiological procedures performed worldwide. A consequence of the wide adoption of CT in clinical practice is that radiation dose from CT is growing as a component of the total radiation dose received by patients and the general population [1^,2]. Data from various national surveys have proved that CT is a major source of radiation exposure and provides a substantial proportion of the collective dose from medical exposure, e.g. approximately 35% in Germany [3] and 47% in the UK [4]. The introduction of faster multislice and dual source CT technology has allowed cardiac CT, large-volume high-resolution CT and improved z-plane resolution [5-8]. The speed and ease of CT imaging and the ambition to obtain quality images and cover larger areas of the patient''s anatomy can lead to increased patient doses; although technological developments provide the opportunity to decreases individual CT doses [9]. Patient radiation dose owing to CT examination is expected to be highly variable because of the use of different imaging protocols and the intrinsic differences among makes and models of CT scanners [10^,11]. To limit radiation exposure arising from CT procedures to as low as reasonably achievable (ALARA), European guidelines on quality criteria were published and specific diagnostic reference levels (DRLs) were proposed for routine CT examinations [12]. The purpose of this study is to review published literature on patient radiation doses from common non-cardiac CT examinations, to compare findings with DRLs, to identify whether patient doses are reduced or increased for newer studies and to comment on the impact of multislice technology on patient doses.     

Pulmonary tuberculosis associated with the reversed halo sign on high-resolution CT

We describe the case of a 32-year-old woman with pulmonary tuberculosis in whom a high-resolution CT scan demonstrated the reversed halo sign. The diagnosis of tuberculosis was made by lung biopsy and the detection of acid-fast bacilli in the sputum smear and culture. Follow-up assessment revealed a significant improvement in the lesions.The reversed halo sign is observed on high-resolution CT (HRCT) as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation [1, 2]. It was first described as being relatively specific for cryptogenic organising pneumonia [1], but was later observed in several other infectious [3–5] and non-infectious [6, 7] diseases.We report a case of a 32-year-old patient with tuberculosis who exhibited the reversed halo sign on chest CT. To our knowledge, this sign has not been previously described in an adult with pulmonary tuberculosis.     

Application of prospective ECG-triggered dual-source CT coronary angiography for infants and children with coronary artery aneurysms due to Kawasaki disease

Objectives

The aim of this study was to prospectively evaluate the initial application and value of prospective electrocardiogram (ECG)-triggered dual-source CT coronary angiography (DSCTCA) in the diagnosis of infants and children with coronary artery aneurysms due to Kawasaki disease.

Methods

19 children [12 males; mean age 13.47 months, range 3 months to 5 years; mean heart rate 112 beats per minute (bpm), range 83–141 bpm] underwent prospective ECG-triggered DSCTCA with free breathing. Subjective image quality was assessed on a five-point scale (1, excellent; 5, non-diagnostic) by two blinded observers. The location, number and size of each aneurysm were observed and compared with those of transthoracic echocardiography (TTE) performed within 1 week. Interobserver agreement concerning the subjective image quality was evaluated with Cohen''s κ-test. Bland–Altman analysis was used to evaluate the agreement on measurements (diameter and length of aneurysms) between DSCTCA and TTE. The average effective dose required for DSCTCA was calculated for all children.

Results

All interobserver agreement for subjective image quality assessment was excellent (κ=0.87). The mean±standard deviation (SD) aneurysm diameter with DSCTCA was 0.76±0.36 cm and with TTE was 0.76±0.39 cm. The mean±SD aneurysm length with DSCTCA was 2.06±1.35 cm and with TTE was 2.00±1.22 cm. The Bland–Altman plot for agreement between DSCTCA and TTE measurements showed good agreement. The mean effective dose was 0.36±0.06 mSv.

Conclusion

As an alternative diagnostic modality, prospective ECG-triggered DSCTCA with excellent image quality and low radiation exposure has been proved useful for diagnosing infants and children with coronary artery aneurysms due to Kawasaki disease.

Advances in knowledge

Prospective ECG–triggered DSCTCA for infants and children allows rapid, accurate assessment of coronary aneurysms due to Kawasaki diseases, compared with TTE.Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is an autoimmune vasculitis in which the small and medium vessels throughout the body become inflamed [1,2]. It predominantly occurs in infants and children (younger than 5 years old). It affects many organ systems; injury, such as aneurysm, dilation, ectasia, stenosis and embolism, to the heart is rare but serious, and fatal myocardial infarction can be induced in untreated cases [3-6]. It is crucial to detect coronary artery lesions at an early stage [7]. Diagnosis of KD is based on clinical signs, symptoms and laboratory findings, but no specific laboratory test exists and it is hard to establish the diagnosis, especially in the early course [8].Recently, multidetector CT, especially the advent of dual-source CT, has provided improved spatial and temporal resolution; moreover, multiple techniques on dose reduction have been applied in children. Electrocardiogram (ECG)-gated scans, especially retrospective ECG-gated scans, have been used to evaluate coronary artery lesions in children with KD [2,9]. The high radiation dose required remains the main concern [10]; even though dose-saving methods including low tube potential, tube current modulation and body size-adapted CT protocols have been adopted, the effective radiation dose is still high at up to 2.17–3.14 mSv [11-13].Recently, prospective ECG-triggered scans were considered to be the most promising approach for dose reduction as they were used in the assessment of cardiovascular deformities in children with congenital heart disease [14-17]; however, no further studies have been reported on the application of prospective ECG-triggered CT angiography in children with KD.The aim of this study was to evaluate the initial application of prospective ECG-triggered dual-source CT coronary angiography (DSCTCA) in infants and children with coronary artery aneurysms due to KD.     

Calcifying cystic odontogenic tumour: CT imaging

Objectives

Calcifying cystic odontogenic tumour (CCOT) is a rare disorder of the jaw. A comparison between conventional radiographs and CT images in CCOTs has not been reported. The purposes of this study were to analyse conventional radiographs and CT images of CCOTs, establish CT images of CCOTs and assess the utility of CT in the diagnosis of CCOTs.

Methods

Nine patients with a histopathologically confirmed CCOT who had both conventional radiographs and CT images were enrolled.

Results

CT was superior to conventional radiographs in detecting buccolingual expansion, odontomas and radio-opaque bodies.

Conclusion

The characteristic CT appearances of CCOT were that radio-opaque bodies were typically located in the periphery of the lesion and the shape of radio-opaque bodies was linear and/or spotted. CT was useful in diagnosing a CCOT.The calcifying odontogenic cyst (COC) was first recognised as a distinct pathological entity by Gorlin et al [1] in 1962. COC is a rare disorder of the jaw [2], and the reported frequency of COCs varies from 0.37 to 2.1% of all odontogenic tumours [3]. In 2005, COC was classified as a tumour and designated as a “calcifying cystic odontogenic tumour” (CCOT) by the World Health Organization (WHO) [4].Histopathologically, the cyst wall is lined by a thin ameloblastomatous epithelium with the formation of ghost cells. These ghost cells may calcify [4], and the frequency of calcification in some of the ghost cells varies from 19 to 77% [5].Radiographically, a CCOT generally appears as a unilocular lesion with a well-defined margin and contains calcification [3]. Few studies have reported on the radiographic features of CCOTs in the English language literature [3,6], although CT image findings of CCOTs have been described [2,3,7]. A comparison between conventional radiographs and CT image findings in CCOTs, however, has not been reported.The purposes of this study were to analyse conventional radiographs and CT images of CCOTs, establish CT images of CCOTs and assess the utility of CT in the diagnosis of CCOTs.     

Comparison of pulmonary thin section CT findings and serum KL-6 levels in patients with sarcoidosis

Objective

This study aimed to compare thin-section CT images from sarcoidosis patients who had either normal or elevated serum KL-6 levels.

Methods

101 patients with sarcoidosis who underwent thin-section CT examinations of the chest and serum KL-6 measurements between December 2003 and November 2008 were retrospectively identified. The study group comprised 75 sarcoidosis patients (23 male, 52 female; aged 19–82 years, mean 54.1 years) with normal KL-6 levels (152–499 U ml^–1, mean 305.7 U ml^–1) and 26 sarcoidosis patients (7 male, 19 female; aged 19–75 years, mean 54.3 years) with elevated KL-6 levels (541–2940 U ml^–1, mean 802.4 U ml^–1). Two chest radiologists, unaware of KL-6 levels, retrospectively and independently interpreted CT images for parenchymal abnormalities, enlarged lymph nodes and pleural effusion.

Results

CT findings in sarcoidosis patients consisted mainly of lymph node enlargement (70/75 with normal KL-6 levels and 21/26 with elevated KL-6 levels), followed by nodules (50 and 25 with normal and elevated levels, respectively) and bronchial wall thickening (25 and 21 with normal and elevated levels, respectively). Ground-glass opacity, nodules, interlobular septal thickening, traction bronchiectasis, architectural distortion and bronchial wall thickening were significantly more frequent in patients with elevated KL-6 levels than those with normal levels (p<0.001, p<0.005, p<0.001, p<0.001, p<0.001 and p<0.001, respectively). By comparison, there was no significant difference in frequency of lymph node enlargement between the two groups.

Conclusion

These results suggest that serum KL-6 levels may be a useful marker for indicating the severity of parenchymal sarcoidosis.KL-6 is a mucin-like high molecular weight glycoprotein that is expressed on Type II pneumocytes and respiratory bronchiolar epithelial cells in the normal lung [1, 2]. Serum levels of KL-6 are elevated in various respiratory and non-respiratory conditions, including breast and pancreatic cancers [3, 4] and diabetes mellitus [5]. This observation has led to a focus on the use of KL-6 as a diagnostic and prognostic tool in respiratory diseases.Serum and bronchoalveolar lavage fluid levels of KL-6, first described by Kohno et al [6] in 1988, were raised in patients with interstitial pneumonia [1, 2, 7]. Several investigators have also reported that KL-6 is a useful serum marker to confirm diagnosis and for long-term management in patients with diffuse pulmonary diseases, particularly interstitial lung diseases. Patients with idiopathic pulmonary fibrosis or non-specific interstitial pneumonia showed significantly elevated KL-6 levels [8-13].Several studies indicate that the serum KL-6 level is elevated in patients with sarcoidosis [14-16]. However, no studies describing radiological findings comparing thin-section CT images between patients with elevated KL-6 levels and those with normal KL-6 levels have been published in the English language literature.Thus, we aimed to retrospectively evaluate and compare pulmonary CT findings between patients with elevated KL-6 levels and those with normal KL-6 levels.     

Automatic vs semi-automatic global cardiac function assessment using 64-row CT

Objective

Global cardiac function assessment using multidetector CT (MDCT) is time-consuming. Therefore we sought to compare an automatic software tool with an established semi-automatic method.

Methods

A total of 36 patients underwent CT with 64×0.5 mm detector collimation, and global left ventricular function was subsequently assessed by two independent blinded readers using both an automatic region-growing-based software tool (with and without manual adjustment) and an established semi-automatic software tool. We also analysed automatic motion mapping to identify end-systole.

Results

The time needed for assessment using the semi-automatic approach (12:12±6:19 min) was reduced by 75–85% with the automatic software tool (unadjusted, 01:34±0:29 min, adjusted, 02:53±1:19 min; both p<0.001). There was good correlation (r=0.89; p<0.001) for the ejection fraction (EF) between the adjusted automatic (58.6±14.9%) and the semi-automatic (58.0±15.3%) approaches. Also the manually adjusted automatic approach led to significantly smaller limits of agreement than the unadjusted automatic approach for end-diastolic volume (±36.4 ml vs ±58.5 ml, p>0.05). Using motion mapping to automatically identify end-systole reduced analysis time by 95% compared with the semi-automatic approach, but showed inferior precision for EF and end-systolic volume.

Conclusion

Automatic function assessment using MDCT with manual adjustment shows good agreement with an established semi-automatic approach, while reducing the analysis by 75% to less than 3 min. This suggests that automatic CT function assessment with manual correction may be used for fast, comfortable and reliable evaluation of global left ventricular function.Multidetector CT (MDCT) has been shown in various reports to offer a high degree of accuracy in identifying coronary artery disease in patients [1-4]. But clinical studies have also shown that, rather than the degree of the coronary stenosis, end-systolic volume (ESV) and ejection fraction (EF) of the left ventricle are the most important predictors for long-term survival and therapy success [5,6].As MDCT allows the acquisition of a complete and continuous volumetric data set, as well as the related electrocardiogram, it is possible to accurately analyse left ventricular (LV) function [4,7-13]. For this, reconstructing short-axis slices, identifying cardiac borders and using Simpson''S rule to calculate the resulting volume is the method of choice. Although this process is (at least in part) semi-automatic and may be sped up using thicker slices [14], the main drawback of this method is the time needed. Times needed ranged from 63±3 min for a full manual approach (reported by Boehm et al [15]) to 15.9±2.8 min (reported by Dewey et al [16], who used a semi-automatic approach, thus being hardly acceptable for daily practice).The recent introduction of systems offering automatic analysis of cardiac function based on a region-growing threshold algorithm shows great promise to overcome this drawback [17-19].The aim of this study was therefore to evaluate an automatic four-dimensional (4D) analysis of a region-growing segmentation algorithm and motion mapping to automatically identify end-systole [20] for the assessment of LV function, taking into account the time needed and the degree of interobserver variability, as well as accuracy when compared with an established semi-automatic short-axis approach.     

Lowering heart rate with an optimised breathing protocol for prospectively ECG-triggered CT coronary angiography

Objectives

The aim was to prospectively characterise the effect of the level of breath-hold on heart rate in CT coronary angiography (CTCA) with prospective electrocardiogram (ECG) triggering and its impact on coronary artery attenuation.

Methods

260 patients (86 women; mean age 59 ± 11 years) underwent 64-slice CTCA using prospective ECG triggering. Prior to CTCA, heart rates were recorded during 15 s of breath-hold at three different levels of inspiration (normal, intermediate and deep). The inspiration level with the lowest heart rate was chosen for actual CTCA scanning. Coronary artery attenuation was measured, and the presence of backflow of contrast material into the inferior vena cava (as an indicator of increased intrathoracic pressure) was recorded.

Results

The mean heart rate at breath-hold was significantly different for the three inspiration levels (normal, 60 ± 8 bpm; intermediate, 59 ± 8 bpm; deep, 57 ± 7 bpm; p<0.001). The maximum heart rate reduction in each patient at breath-hold averaged 5.3 ± 5.1 bpm, and was observed at a normal inspiration depth in 23 (9%) patients, at an intermediate inspiration depth in 102 (39%) patients and at deep inspiration in 135 (52%) patients. Overall, there was no association between the level of breath-hold and coronary vessel attenuation (p-value was not significant). However, the backflow of contrast material into the inferior vena cava (n = 26) was found predominantly at deep inspiration levels (p<0.001), and, when it occurred, it was associated with reduced coronary attenuation compared with patients with no backflow (p<0.05).

Conclusion

The breath-hold level to best reduce heart rate for CTCA should be individually assessed prior to scanning because a mean heart rate reduction of 5 bpm can be achieved.Low-dose CT coronary angiography (CTCA) with prospective electrocardiogram (ECG) triggering has recently been introduced [1] and shown to offer a tremendous reduction in radiation dose [2-8], which makes its widespread clinical use feasible. Scanning in CTCA with prospective ECG triggering is exclusively performed during a short phase in diastole, called “diastasis”. The new technique appears to be more prone to artefacts caused by coronary motion. This is especially true in higher heart rates because diastasis disproportionally shortens with increasing heart rates [9] and the length of diastasis becomes shorter than the time required for image acquisition when the heart rate exceeds a certain threshold. Furthermore, when low-dose CTCA with prospective ECG triggering is performed with the smallest possible acquisition window to achieve the lowest possible radiation dose, it does not permit image reconstruction in other phases of the cardiac cycle to compensate for a possible reduction in image quality. An aggressive reduction in heart rate with β-blockers below a target heart rate of 63 bpm appears to be a prerequisite for low-dose CTCA [2,10].CTCA is generally performed during the patient''s breath-hold to avoid motion artefacts caused by movement of the thorax during image acquisition. However, the breath-hold and, particularly, the level (or depth) of breath-hold can affect heart rate [11]. Generally, heart rate is lowest at full vital capacity (deep inspiration) and highest at residual volume (normal inspiration) [11]. However, other factors, such as intrapleural and intrathoracic pressure and neural reflexes also determine the heart rate during breath-hold [11]. The lowest heart rates are not always reached at deep inspiration level during breath-hold. Furthermore, during CTCA, very deep inspiration for breath-hold may lead to an increased intrathoracic pressure (Valsalva effect), which may itself impair contrast material flow from the arm veins to the coronary arteries, and thus cause reduced coronary artery attenuation and decreased image quality.Accordingly, the purpose of this study was to describe and characterise the effect of breath-hold on heart rate and on coronary artery attenuation in CTCA with prospective ECG triggering.     

Safety and efficacy of oral ivabradine as a heart rate-reducing agent in patients undergoing CT coronary angiography

Objective

To investigate the role of oral ivabradine as a heart rate reducing agent in patients undergoing CT coronary angiography (CTCA). Despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm. Ivabradine is a selective inhibitor of the I_f current, which primarily contributes to sinus node pacemaker activity, and has no significant direct cardiovascular effects such as reduction of blood pressure, cardiac contractility or impairment of cardiac conduction.

Methods

We investigated 100 consecutive patients who had been referred for CTCA for the evaluation of suspected coronary artery disease (CAD). Patients were randomised to receive either of the following two pre-medication protocols: oral metorprolol or oral ivabradine.

Results

Ivabradine was significantly more effective than metorprolol in lowering the heart rate; the mean percentage reduction in heart rate with ivabradine vs metorpolol was 23.89+6.95% vs 15.20+4.50%, respectively (p=0.0001). Metoprolol significantly lowered both systolic and diastolic blood pressure while ivabradine did not. The requirement of additional doses to achieve a target heart rate of <65 beats per min was also significantly more frequent with metoprolol.

Conclusion

Ivabradine is a potentially attractive alternative to currently used drugs for reduction of heart rate in patients undergoing CTCA.Since the introduction of CT coronary angiography (CTCA) as a non-invasive tool for coronary artery imaging, its clinical utility has been established in various studies [1-3]. However, the presence of motion artefacts often prevents optimal reconstruction of individual coronary arteries, prompting use of pharmacological interventions (primarily β-blockers) during scanning to enhance image quality [4,5]. A target heart rate of 65 beats per min (bpm) or less provides optimum image quality in most cases [6,7]. Though calcium channel-blockers have also been used as alternatives to β-blockers [8], there still exists a subset of patients in whom the administration of these rate-lowering drugs may be hazardous (e.g. those with baseline blood pressure <100–110 mmHg, severe left ventricular dysfunction, peripheral vascular disease or severe obstructive airway disease). Moreover, despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm [9-11].There is a clear need for assessment of the potential role of alternative rate-lowering drugs in patients undergoing CTCA. Ivabradine, a novel heart rate-lowering agent, is a selective and specific inhibitor of the I_f current, which is one of the most important ionic currents for regulating pacemaker activity in the sinoatrial (SA) node [12-14]. This is primarily a mixed Na⁺–K⁺ inward current activated by hyperpolarisation and modulated by the autonomic nervous system, and ivabradine acts by selectively inhibiting the pacemaker I_f current and slowing the diastolic depolarisation slope of SA node cells, reducing both resting and exercise heart rate. Moreover, ivabradine inhibits the I_f current at concentrations that do not affect other cardiac ionic currents, resulting in a lack of haemodynamic effects such as reduction of blood pressure or cardiac contractility, which is often a limitation with β-blockers. It has a good safety profile without any effects on atrioventricular conduction, corrected QT interval and peripheral vasomotion, and there is no rebound effect with drug cessation or tolerance with prolonged use.We investigated the safety and efficacy of oral ivabradine as a heart rate-lowering agent in patients undergoing CTCA at our institute. The aims of the study were (1) to assess the efficacy of ivabradine in achieving adequate heart rate control (defined as target heart rate <65 bpm), (2) to compare the differences (if any) between ivabradine and the β-blocker metoprolol in achieving target heart rate prior to CTCA and (3) to compare any difference in numbers of patients requiring additional doses of drugs prior to achieving the target heart rate.     

Miliary tuberculosis: a comparison of CT findings in HIV-seropositive and HIV-seronegative patients

The aim of this study was to determine the differences in CT findings of miliary tuberculosis in patients with and without HIV infection. Two radiologists reviewed retrospectively the CT findings of 15 HIV-seropositive and 14 HIV-seronegative patients with miliary tuberculosis. The decisions on the findings were reached by consensus. Statistical analysis was performed using the χ² test, Mann–Whitney U-test and Fisher''s exact test. All of the HIV-seropositive and -seronegative patients had small nodules and micronodules distributed randomly throughout both lungs. HIV-seropositive patients had a higher prevalence of interlobular septal thickening (p = 0.017), necrotic lymph nodes (p = 0.005) and extrathoracic involvement (p = 0.040). The seropositive patients had a lower prevalence of large nodules (p = 0.031). In conclusion, recognition of the differences in the radiological findings between HIV-seropositive and -seronegative patients may help in the establishment of an earlier diagnosis of immune status in patients with miliary tuberculosis.Miliary tuberculosis (TB), which results from lympho-haematogenous dissemination of Mycobacterium tuberculosis, is a complication of both primary and post-primary TB [1, 2]. This disease results in the formation of small discrete foci of granulomatous tissue, which are uniformly distributed throughout the lung [3].An increase in TB incidence, including miliary TB, has been associated with infection by human immunodeficiency virus (HIV) [4]. In 2005, the World Health Organization estimated that 12% of HIV deaths globally were caused by TB, and that there were 630 000 new co-infections with TB and HIV [5]. Disseminated TB accounted for 5.4–8.1% of culture-confirmed TB cases, with 10–14% of patients coinfected with HIV having clinically recognisable dissemination [6, 7].Chest radiography may be helpful in the detection and final diagnosis of miliary TB. The characteristic radiographical findings consist of the presence of fine granular or numerous small nodular opacities measuring 1–3 mm in diameter scattered throughout both lungs [1, 3, 8, 9]. However, the radiograph may appear to be normal in the early stage of disease or in cases with nodules below the threshold of perceptibility; therefore, a diagnosis of miliary TB from chest radiographs can be difficult [10].Several studies have shown that CT imaging is more sensitive for the detection of parenchymal abnormalities in patients with AIDS who have active intrathoracic disease, and it has been suggested that CT may also be helpful in the differential diagnosis [11–14]. In addition, it has been reported that certain imaging techniques provided by multidetector-row CT are useful for the diagnosis of multiple micronodular infiltrative lung disease [15]. CT findings of miliary TB have been described in previous reports [16–18]; however, only a few studies on miliary TB in patients with HIV, particularly with reference to the CD4 count, have been reported [19, 20]. The radiographic manifestations of HIV-associated pulmonary TB are thought to be dependent upon the level of immunosuppression at the time of overt disease [21–23].The purpose of this study was to determine the differences in the CT findings of miliary TB for patients with and without HIV infection and to analyse any correlation between the CT features and the level of immunosuppression in patients.     

Hepatocellular carcinoma in cirrhotic patients at multidetector CT: hepatic venous phase versus delayed phase for the detection of tumour washout

Objectives

Our aim was to compare retrospectively hepatic venous and delayed phase images for the detection of tumour washout during multiphasic multidetector row CT (MDCT) of the liver in patients with hepatocellular carcinoma (HCC).

Methods

30 cirrhotic patients underwent multiphasic MDCT in the 90 days before liver transplantation. MDCT was performed before contrast medium administration and during hepatic arterial hepatic venous and delayed phases, images were obtained at 12, 55 and 120 s after trigger threshold. Two radiologists qualitatively evaluated images for lesion attenuation. Tumour washout was evaluated subjectively and objectively. Tumour-to-liver contrast (TLC) was measured for all pathologically proven HCCs.

Results

48 HCCs were detected at MDCT. 46 of the 48 tumours (96%) appeared as either hyper- or isoattenuating during the hepatic arterial phase subjective washout was present in 15 HCCs (33%) during the hepatic venous phase and in 35 (76%) during the delayed phase (p<0.001, McNemar’s test). Objective washout was present in 30 of the 46 HCCs (65%) during the hepatic venous phase and in 42 of the HCCs (91%) during the delayed phase (p=0.001). The delayed phase yielded significantly higher mean TLC absolute values compared with the hepatic venous phase (−16.1±10.8 HU vs −10.5±10.2 HU; p<0.001).

Conclusions

The delayed phase is superior to the hepatic venous phase for detection of tumour washout of pathologically proven HCC in cirrhotic patients.Multiphasic contrast-enhanced multidetector row CT (MDCT) plays a pivotal role in the diagnostic work-up of cirrhotic patients, who are at increased risk of developing hepatocellular carcinoma (HCC) [1]. Increased enhancement of the tumour compared with the surrounding liver parenchyma during the hepatic arterial phase is the cornerstone for the diagnosis of HCC at multiphasic MDCT [1,2]. However, a variety of entities—dysplastic nodules [3], confluent hepatic fibrosis [4], non-tumourous arterioportal shunts [5] and haemangioma [6]—can also manifest with increased arterial enhancement and thus mimic HCC, particularly if they are smaller than 2 cm in diameter.Tumour washout, i.e. hypoattenuation relative to the adjacent hepatic parenchyma during the hepatic venous or delayed phase, has been recognised as a strong predictor of HCC [7,8]. This sign has been included, along with the presence of hypervascularity, in the latest American Association for the Study of Liver Diseases (AASLD) guidelines for the diagnosis of HCC at multiphasic MDCT, MRI or contrast-enhanced ultrasonography [1]. Although it is well known that tumour enhancement is best visualised during the late hepatic arterial phase [9,10], there is no consensus regarding the correct timing for the detection of tumour washout at multiphasic MDCT of the liver. Most commonly, the hepatic arterial phase is followed by the hepatic venous phase, acquired 60–70 s after injection of contrast material [9-12]. In addition, a delayed phase, acquired from 2–10 min after contrast material injection, can follow the hepatic venous phase [13-20] or can occur alone after the hepatic arterial phase [21-23]. Regardless of the phase sequence chosen, to the best of our knowledge, no study has yet compared the hepatic venous and delayed phases for the detection of tumour washout in patients with HCC. The purpose of our study was to compare retrospectively the hepatic venous and delayed phases for the detection of tumour washout during multiphasic MDCT of the liver in patients with HCC who underwent liver transplantation.     

Comparison between the image quality of multisegment and halfscan reconstructions of non-invasive CT coronary angiography

The purpose of this study was to compare the image quality of multisegment and halfscan reconstructions of multislice computed tomography (MSCT) coronary angiography. 126 patients with suspected coronary artery disease and uninfluenced heart rates were examined by 16-slice CT before they underwent invasive coronary angiography. Multisegment and halfscan reconstructions were performed in all patients, and subjective image quality, overall vessel length, vessel length free of motion artefacts and contrast-to-noise ratios (CNRs) were compared for both techniques. The diagnostic accuracy of both approaches was compared with the results of invasive coronary angiography. Overall image quality scores of multisegment reconstruction were superior to those of halfscan reconstruction (13.3±2.1 vs 11.9±2.9; p<0.001). Multisegment reconstruction depicted significantly longer overall coronary vessel lengths (p<0.001) and larger vessel proportions free of motion artefacts in three of the four main coronary arteries. CNRs in the left main, left anterior descending and left circumflex coronary arteries were significantly higher when multisegment reconstruction was used (p<0.001). Overall accuracy was higher for multisegment reconstruction compared with halfscan reconstruction (87% vs 62%). In conclusion, multisegment reconstruction significantly improves image quality and diagnostic accuracy of MSCT coronary angiography compared with standard halfscan reconstruction, resulting in vessel lengths depicted free of motion comparable to those of CT performed in patients given β-blockers to lower heart rates.Non-invasive coronary angiography is an alternative approach to conventional coronary angiography in patients with suspected coronary artery disease (CAD) with high clinical [1–4] and economic [5] relevance. Recently, multislice computed tomography (MSCT) has developed into the most reliable non-invasive method for imaging of the whole coronary artery tree [6]. The susceptibility of MSCT to motion artefacts can only be overcome by systematic pre-scan β-blockade to lower heart rates to target values below 65 beats per minute (bpm). Recent studies have shown that β-blocker administration is necessary even on 64-slice scanners [4, 7–11]. Motion artefacts result from a relatively long acquisition window, which is determined by the gantry rotation time in standard halfscan reconstruction. In contrast, multisegment reconstruction [12] reduces the acquisition time by using up to four different segments from up to four consecutive heart beats [13]. In this way, an acquisition window as short as one-eighth of the gantry rotation time can be achieved [14]. In a small retrospective study of 34 patients with suspected CAD, multisegment reconstruction showed superior image quality and diagnostic accuracy compared with halfscan reconstruction. Based on these results, it was suggested that there is no need for β-blocker administration when multisegment reconstruction is used [15]. However, a recently published subgroup analysis of patients with different heart rates showed that image quality and diagnostic performance of multisegment reconstruction varied with heart rate [16]. Therefore, the use of β-blockers was recommended in patients with heart rates above 75 bpm when using multisegment reconstruction.In this study, we analysed prospectively the overall image quality and diagnostic accuracy of multisegment reconstruction compared with halfscan reconstruction in a large consecutive group of patients with uninfluenced heart rates to determine whether systematic β-blockade is needed.     

CT in the clinical and prognostic evaluation of acute graft-vs-host disease of the gastrointestinal tract

Objective

To determine the role of abdominal CT in assessment of severity and prognosis of patients with acute gastrointestinal (GI) graft-vs-host disease (GVHD).

Methods

During 2000–2004, 41 patients with a clinical diagnosis of acute GI-GVHD were evaluated. CTs were examined for intestinal and extra-intestinal abnormalities, and correlated with clinical staging and outcome.

Results

20 patients had GVHD clinical Stage I–II and 21 had Stage III–IV. 39 (95%) had abnormal CT appearances. The most consistent finding was bowel wall thickening: small (n=14, 34%) or large (n=5, 12%) bowel, or both (n=20, 49%). Other manifestations included bowel dilatation (n=7, 17%), mucosal enhancement (n=6, 15%) and gastric wall thickening (n=9, 38%). Extra-intestinal findings included mesenteric stranding (n=25, 61%), ascites (n=17, 41%), biliary abnormalities (n=12, 29%) and urinary excretion of orally administered gastrografin (n=12, 44%). Diffuse small-bowel thickening and any involvement of the large bowel were associated with severe clinical presentation. Diffuse small-bowel disease correlated with poor prognosis. 8 of 21 patients responded to therapy, compared with 15 of 20 patients with other patterns (p=0.02), and the cumulative incidence of GVHD-related death was 62% and 24%, respectively (p=0.01). Overall survival was not significantly different between patients with diffuse small-bowel disease and patients with other patterns (p=0.31). Colonic disease correlated with severity of GVHD (p=0.04), but not with response to therapy or prognosis (p=0.45).

Conclusion

GVHD often presented with abdominal CT abnormalities. Diffuse small-bowel disease was associated with poor therapeutic response. CT may play a role in supporting clinical diagnosis of GI GVHD and determining prognosis.Allogeneic stem-cell transplantation (SCT) has been used increasingly to treat haematopoietic disorders and haematological malignancies [1,2]. Among the complications of SCT, graft-vs-host disease (GVHD) is one of the major causes of morbidity and mortality [3-5]. Intestinal GVHD is one of the most frequent features of acute GVHD. Gastrointestinal (GI) symptoms include abdominal pain, nausea, vomiting and profuse diarrhoea [5-8]. The diagnosis and grading of the disease are based on a spectrum of clinical and laboratory features. Clinical parameters such as the quantity of diarrhoea are used to determine the clinical severity of GI GVHD [9]. These are, however, not very accurate, as assessment of the volume of diarrhoea is inconvenient and inaccurate. Endoscopic evaluation, with histological examination of biopsy specimens, can be useful for diagnosing and staging intestinal GVHD [10-12]. However, GI biopsies may be hazardous in patients with severe thrombocytopenia, coagulopathy and granulopenia [13]. Moreover, both endoscopic evaluation and histology can underestimate the severity of the disease [14].Recently, non-invasive methods have been used to assess the extent and severity of intestinal GVHD, including CT [15-20], high-resolution ultrasonography [21,22], MRI [23] and positron emission tomography with fluorodeoxyglucose (PET-FDG) [24]. Abdominal CT has been the main modality, showing abnormal findings in gastrointestinal GVHD [16,25] which correlate with both pathological [18] and clinical grading [20]. No study has as yet tried to correlate these CT findings with the outcome of the disease. This study was therefore designed to determine the role of abdominal CT in the assessment of severity and prognosis of patients with acute intestinal GVHD.     

Accessory or additional renal arteries show no relevant effects on the width of the upper urinary tract: a 64-slice multidetector CT study in 1072 patients with 2132 kidneys

Objective

The aim of this study was to find out on an unselected patient group whether crossing vessels have an influence on the width of the renal pelvis and what independent predictors of these target variables exist.

Methods

In this cross-sectional study, 1072 patients with arterially contrasted CT scans were included. The 2132 kidneys were supplied by 2736 arteries.

Results

On the right side, there were 293 additional and accessory arteries in 286 patients, and on the left side there were 304 in 271 patients. 154 renal pelves were more than 15 mm wide. The greatest independent factor for hydronephrosis on one side was hydronephrosis on the contralateral side (p<0.0001 each). Independent predictors for the width of the renal pelvis on the right side were the width of the renal pelvis on the left, female gender, increasing age and height; for the left side, predictors were the width of the renal pelvis on the right, concrements, parapelvic cysts and great rotation of the upper pole of the kidney to dorsal. Crossing vessels had no influence on the development of hydronephrosis. Only anterior crossing vessels on the right side are associated with widening of the renal pelvis by 1 mm, without making it possible to identify the vessel as an independent factor in multivariate regression models.

Conclusion

The width of the renal pelvis on the contralateral side is the strongest independent predictor for hydronephrosis and the width of the renal pelvis. There is no link between crossing vessels and the width of the renal pelvis.Obstructions of the ureteropelvic junction (UPJ) can be caused by intrinsic or extrinsic factors [1]. Although there are no studies of this to date, crossing the UPJ by an aberrant crossing vessel is considered the most important [2] of the extrinsic factors [3]. Crossing vessels, which are thought to cause from 40% to over 50% of the extrinsic UPJ obstructions in adults [4, 5], are located ventral more often than dorsal to the UPJ. These are usually normal vessels of the lower pole segment [4, 6–9], which can be divided into additional renal arteries arising from the aorta, and accessoric renal arteries arising from branches of the aorta [10, 11]. The primary surgical therapy of choice is endoscopic endopyelotomy [12]. The success rate of 89–90% [12, 13] is thought to be noticeably poorer in patients with crossing vessels [12, 13]; however, this is not undisputed [14, 15]. Be that as it may, to prevent bleeding complications it is necessary to be familiar with the vascular situation around the UPJ prior to the procedure [3, 16–18]. CT angiography is used for this purpose, as it is highly accurate, quick to perform and shows all relevant anatomical structures in relation to one another [3, 19, 20]. The objective of this study was to determine whether or not there are vascular morphological patterns or other factors that influence the width of the renal collecting system, regardless of the definitions of hydronephrosis.     

Diagnostic performance of multidetector CT for acute cholangitis: evaluation of a CT scoring method

Objective

The aim of this study was to retrospectively assess the diagnostic performance of multidetector CT (MDCT) for the diagnosis of acute cholangitis using a new scoring method.

Methods

Of 80 patients with suspected biliary disease who underwent biphasic CT and endoscopic retrograde cholangiography, 39 were diagnosed as having acute cholangitis (Group 1) and 41 patients were classified as suspected biliary disease (Group 2). 100 age-matched patients without evidence of biliary disease were selected randomly as a control group (Group 3). Each patient''s axial scan was scored by two independent radiologists for the extent of transient hepatic attenuation difference, the presence of biliary dilatation and identification of a biliary obstructive lesion. The difference in the scores among the three groups was evaluated and the optimal cut-off score for the diagnosis of acute cholangitis was determined. Interobserver agreement was also evaluated.

Results

The total scores (mean±standard deviation) for Groups 1, 2 and 3 were 7.0±2.0, 4.4±2.4 and 0.9±1.2, respectively, for Reviewer 1 and 7.2±1.8, 4.3 ±2.7 and 0.7±1.1, respectively, for Reviewer 2. Significant differences were found for the subscores and the total scores among the three groups (p<0.001). Using a cut-off score of ≥5, the sensitivity and specificity for diagnosing acute cholangitis were 84.6% and 83.7%, respectively, for Reviewer 1 and 89.7% and 83.7%, respectively, for Reviewer 2. Agreement for the subscores between readers was good to excellent (κ=0.74–0.86).

Conclusion

Based on dynamic MDCT and the described CT scoring method, the diagnosis of acute choangitis can be made with high sensitivity and specificity.Acute cholangitis is a potentially life-threatening condition that occurs as a result of acute inflammation and infection in an obstructed bile duct [1,2]. Because both biliary obstruction and bile infection are required for the development of acute cholangitis, these factors are essential to the pathophysiology and diagnosis of this entity [3,4].Traditionally, the clinical manifestations, including Charcot''s triad (the presence of fever and/or chills, abdominal pain and jaundice), have been regarded as important factors for making the diagnosis of acute cholangitis [1-4]. However, the frequency of Charcot''s triad varies and has been reported to be present in 15.4–72.0% of patients [4]. Diagnostic criteria were established by. the International Consensus Meeting, held in Tokyo in 2006 [4]. The diagnostic criteria for a definite diagnosis of acute cholangitis include the presence of Charcot''s triad. In addition, laboratory data and imaging findings are needed to support the clinical diagnosis in patients without all of the components of Charcot''s triad. In this situation, laboratory data provide information about infection/inflammation and imaging is used to determine the degree and level of the biliary obstruction and to identify the obstructing lesion in the bile duct. In previous studies, multidetector CT (MDCT) has been shown to be an accurate imaging tool for the detection of biliary obstruction [5,6].Transient hepatic attenuation differences (THADs), which appear as focal or diffuse hyperdense areas during the hepatic arterial phase on the CT, have been reported to be common in patients with acute cholangitis [7-9]. The incidence of THADs in patients with acute cholangitis has ranged from 71% to 98%. In addition, one study reported that the THADs observed in patients with suspected biliary disease correlated with the clinical parameters of inflammation [9]. Therefore, we developed a new scoring method for the diagnosis of acute cholangitis using dynamic contrast-enhanced MDCT. This method considers two important diagnostic factors: biliary obstruction and biliary inflammation. The purpose of this study was to retrospectively assess the diagnostic performance of MDCT for the diagnosis of acute cholangitis using a new scoring system.