Detection of coronary artery stenosis with sub-milliSievert radiation dose by prospectively ECG-triggered high-pitch spiral CT angiography and iterative reconstruction

Objectives

To evaluate the diagnostic accuracy of sub-milliSievert (mSv) coronary CT angiography (cCTA) using prospectively ECG-triggered high-pitch spiral CT acquisition combined with iterative image reconstruction.

Methods

Forty consecutive patients (52.9?±?8.7 years; 30 men) underwent dual-source cCTA using prospectively ECG-triggered high-pitch spiral acquisition. The tube current-time product was set to 50 % of standard-of-care CT examinations. Images were reconstructed with sinogram-affirmed iterative reconstruction. Image quality was scored and diagnostic performance for detection of ≥50 % stenosis was determined with catheter coronary angiography (CCA) as the reference standard.

Results

CT was successfully performed in all 40 patients. Of the 601 assessable coronary segments, 543 (90.3 %) had diagnostic image quality. Per-patient sensitivity for detection of ≥50 % stenosis was 95.7 % [95 % confidence interval (CI), 76.0-99.8 %] and specificity was 94.1 % (95 % CI, 69.2-99.7 %). Per-vessel sensitivity was 89.5 % (95 % CI, 77.8-95.6 %) with 93.2 % specificity (95 % CI, 86.0-97.0 %). The area under the receiver-operating characteristic curve on per-patient and per-vessel levels was 0.949 and 0.913. Mean effective dose was 0.58?±?0.17 mSv. Mean size-specific dose estimate was 3.14?±?1.15 mGy.

Conclusions

High-pitch prospectively ECG-triggered cCTA combined with iterative image reconstruction provides high diagnostic accuracy with a radiation dose below 1 mSv for detection of coronary artery stenosis.

Key Points

? Cardiac CT with sub-milliSievert radiation dose is feasible in many patients ? High-pitch spiral CT acquisition with iterative reconstruction detects coronary stenosis accurately. ? Iterative reconstruction increases who can benefit from low-radiation cardiac CT.     

Detection of residual packets in cocaine body packers: low accuracy of abdominal radiography—a prospective study

Objective

To evaluate the accuracy of abdominal radiography (AXR) for the detection of residual cocaine packets by comparison with computed tomography (CT).

Methods

Over a 1-year period unenhanced CT was systematically performed in addition to AXR for pre-discharge evaluation of cocaine body packers. AXR and CT were interpreted independently by two radiologists blinded to clinical outcome. Patient and packet characteristics were compared between the groups with residual portage and complete decontamination.

Results

Among 138 body packers studied, 14 (10 %) had one residual packet identified on pre-discharge CT. On AXR, at least one reader failed to detect the residual packet in 10 (70 %) of these 14 body packers. The sensitivity and specificity of AXR were 28.6 % (95 % CI: 8.4–58.1) and 100.0 % (95 % CI: 97.0–100.0) for reader 1 and 35.7 % (95 % CI: 12.8–64.9) and 97.6 % (95 % CI: 93.1–99.5) for reader 2. There were no significant patient or packet characteristics predictive of residual portage or AXR false negativity. All positive CT results were confirmed by delayed expulsion or surgical findings, while negative results were confirmed by further surveillance.

Conclusion

Given the poor performance of AXR, CT should be systematically performed to ensure safe hospital discharge of cocaine body packers.

Key Points

? Both abdominal radiography and computed tomography can identify gastrointestinal cocaine packets. ? Ten per cent of body packers had residual packets despite two packet-free stools. ? Seventy per cent of these residual packets were missed on AXR. ? No patient or packet characteristics predicted residual packets or AXR false negativity. ? CT is necessary to ensure safe medical discharge of body packers.     

Diagnostic performance of computed tomography angiography and contrast-enhanced magnetic resonance angiography in patients with critical limb ischaemia and intermittent claudication: systematic review and meta-analysis

Objective

To evaluate the diagnostic performance of computed tomography angiography (CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA) in detecting haemodynamically significant arterial stenosis or occlusion in patients with critical limb ischaemia (CLI) or intermittent claudication (IC).

Methods

Medline and Embase were searched for studies comparing CTA or CE-MRA with digital subtraction angiography as a reference standard, including patients with CLI or IC. Outcome measures were aortotibial arterial stenosis of more than 50 % or occlusion. Methodological quality of studies was assessed using QUADAS.

Results

Out of 5,693 articles, 12 CTA and 30 CE-MRA studies were included, respectively evaluating 673 and 1,404 participants. Summary estimates of sensitivity and specificity were respectively 96 % (95 % CI, 93–98 %) and 95 % (95 % CI, 92–97 %) for CTA, and 93 % (95 % CI, 91–95 %) and 94 % (95 % CI, 93–96 %) for CE-MRA. Regression analysis showed that the prevalence of CLI in individual studies was not an independent predictor of sensitivity and specificity for either technique. Methodological quality of studies was moderate to good.

Conclusion

CTA and CE-MRA are accurate techniques for evaluating disease severity of aortotibial arteries in patients with CLI or IC. No significant differences in the diagnostic performance of the two techniques between patients with CLI and IC were found.

Key Points

? Computed tomography and contrast-enhanced magnetic resonance angiography can both demonstrate arterial disease. ? CTA and CE-MRA can both accurately evaluate arteries in peripheral arterial disease. ? Diagnostic performances of critical limb ischaemia and intermittent claudication are not different. ? Separate imaging technique of tibial arteries by CE-MRA is preferred. ? CTA and CE-MRA can distinguish confidently between high-grade stenoses and occlusions.     

Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols

Objectives

To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction.

Methods

We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients.

Results

In group A (231 patients, 146 men, mean heart rate 58?±?7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P?=?0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P?>?0.05) but radiation dose was lower (1.16?±?0.60 vs. 3.82?±?1.65 mSv, P?<?0.001). In group B (228 patients, 132 men, mean heart rate 75?±?11 bpm), per-segment sensitivity, specificity, PPV and NPV were comparable (94 %, 95 %, 67 %, 99 % vs. 92 %, 95 %, 66 %, 99 %, P?>?0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12?±?2.58 vs. 8.13?±?4.52 mSv, P?<?0.001). Diagnostic performance was comparable in both groups.

Conclusion

Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose.

Key Points

? 128-slice dual-source CT coronary angiography offers several different acquisition protocols. ? Randomized comparison of protocols reveals an optimal protocol selection strategy. ? Appropriate CTCA protocol selection lowers radiation dose, while maintaining high quality. ? CTCA protocol selection should be based on individual patient characteristics. ? A prospective sequential protocol is preferred for CTCA.     

Accuracy of automated software-guided detection of significant coronary artery stenosis by CT angiography: comparison with invasive catheterisation

Purpose

True automated detection of coronary artery stenoses might be useful whenever expert evaluation is not available, or as a “second reader” to enhance diagnostic confidence. We evaluated the accuracy of a PC-based stenosis detection tool alone and combined with expert interpretation.

Methods

One hundred coronary CT angiography datasets were evaluated with the automated software alone, by manual interpretation (axial images, multiplanar reformations and maximum intensity projections in free double-oblique planes), and by expert interpretation aware of the automated findings. Stenoses ≥?50 % were noted per-vessel and per-patient, and compared with invasive angiography.

Results

Automated post-processing was successful in 90 % of patients (88 % of vessels). When excluding uninterpretable datasets, per-patient sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 89 %, 79 %, 74 % and 92 % (per-vessel: 82 %, 85 %, 48 % and 96 %). All 100 datasets were evaluable by expert interpretation. Per-patient sensitivity, specificity, PPV and NPV were 95 %, 95 %, 93 % and 97 % (per-vessel: 89 %,98 %, 88 % and 98 %). Knowing the results of automated interpretation did not improve the performance of expert readers.

Conclusion

Automated off-line post-processing of coronary CT angiography shows adequate sensitivity, but relatively low specificity in coronary stenosis detection. It does not increase accuracy of expert interpretation. Failure of post-processing in 10 % of all patients necessitates additional manual image work-up.

Key Points

? Coronary CT angiography is increasingly used for detection of coronary artery stenosis ? Computer assisted diagnosis might facilitate and speed up interpretation ? Performance in properly segmented cases compared favourably with manual image interpretation ? However, automated segmentation failed in about 10 % of cases ? Manual reading is still mandatory; computer assisted diagnosis can provide a useful second read     

Meta-analysis: diagnostic accuracy of coronary CT angiography with prospective ECG gating based on step-and-shoot,Flash and volume modes for detection of coronary artery disease

Objectives

To investigate the diagnostic performance of coronary computed tomographic angiography (CCTA) with prospective electrocardiograph (ECG) gating based on step-and-shoot (SAS), Flash and volume imaging modes.

Methods

We searched the electronic databases PubMed for all published studies regarding CCTA. We used an exact binomial rendition of the bivariate mixed-effects regression model developed for synthesis of diagnostic data.

Results

A total of 21,852 segments, 4,851 vessels and 1,375 patients were identified using database searches. Patient-level pooled sensitivity was 0.99 (95 % confidence interval [CI], 0.98–1.00); specificity was 0.88 (CI, 0.85–0.91). The results showed that the sensitivity and specificity for detection of significant stenosis did not differ in the three protocols (P?=?0.24). No heterogeneity was found at the patient level for sensitivity (Q?=?26.23; P?=?0.12; I ²?=?27.56 % [CI, 0.00-67.02 %]) and specificity (Q?=?19.54; P?=?0.42; I ²?=?2.78 % [CI, 0.00-66.26 %]).

Conclusions

CCTA with prospective ECG gating has similar high diagnostic value to rule out CAD in all three presented modes.

Key Points

? The accuracy of CCTA with different prospective ECG gating is similar ? CCTA with prospective ECG gating is effective to exclude coronary artery disease ? The radiation dose of volume mode increases with higher heart rate     

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease

Objectives

To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD (“high-risk” CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score.

Materials and methods

Between 2004 and 2011, a total of 1,159 symptomatic patients (61?±?11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis).

Results

A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91–97 %), 83 % (80–85 %), 53 % (48–58 %), 99 % (98–99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P?<?0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Conclusions

CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Key Points

? Computed tomography coronary angiography (CTCA) accurately excludes high-risk coronary artery disease. ? CTCA overestimates high-risk coronary artery disease in 47?%. ? CTCA discriminates high-risk CAD better than clinical evaluation and coronary calcification.     

Computed tomography angiography of lower extremities in the emergency room for evaluation of patients with gunshot wounds

Objective

To assess the role of CT angiography in the evaluation of patients with lower extremity gunshot wounds in the emergency room.

Materials and methods

Eighty patients (73 male, 7 female, mean age 26 years) underwent CT angiography for the evaluation of lower extremity gunshot injuries. Imaging was conducted on the basis of standardized protocols utilizing 16-slice and 64-slice multidetector systems and images were qualitatively graded and assessed for various forms of arterial injury.

Results

CT angiography findings indicative of arterial injury were observed in 24 patients (30 %) and a total of 43 arterial injuries were noted; the most common form was focal narrowing/spasm (n?=?16, 37.2 %); the most common artery involved was the superficial femoral artery (n?=?12, 50 %). In qualitative assessment of images based on a 4-point grading system, both readers considered CT angiography diagnostically excellent (grade 4) in most cases. Surgical findings were consistent with CT angiography and follow-up of patients’ medical records showed no arterial injuries in patients with normal findings on initial imaging.

Conclusion

Our findings demonstrate that CT angiography is an effective imaging modality for evaluation of lower extremity gunshot wounds and could help limit more invasive procedures such as catheter angiography to a select group of patients.

Key Points

? CT angiography efficiently evaluates lower extremity gunshot wounds. ? CT angiography provides image quality sufficiently reliable for assessment of gunshot injuries. ? CT angiography could help limit invasive procedures to select patients.     

Tube potential can be lowered to 80 kVp in test bolus phase of CT coronary angiography (CTCA) and CT pulmonary angiography (CTPA) to save dose without compromising diagnostic quality

Objectives

The purpose of this study was to determine whether performing the test bolus (TB) of computed tomography coronary angiography (CTCA) and computed tomography pulmonary angiography (CTPA) at 80 kVp reduces dose without compromising diagnostic quality.

Methods

An 80 kVp TB protocol for CTCA and CTPA was retrospectively compared to standard TB protocol (non-obese: 100 kVp, obese: 120 kVp). CT angiogram parameters were unchanged between cohorts. Thirty-seven consecutive 80 kVp TB CTCA images were compared to 53 standard CTCA images. Fifty consecutive CTPAs from each protocol were analysed. Diagnostic quality of the CT angiogram was assessed by: mean attenuation, signal-to-noise ratio (SNR) in the ascending aorta (AA) in CTCA and in the main pulmonary artery (MPA) in CTPA, diagnostic rate, and number of repeated monitoring scans. Mean effective dose was estimated using the dose-length product.

Results

Mean TB effective doses were significantly lower (P?Conclusions Routinely performing TB at 80 kVp, regardless of body habitus, in CTCA and CTPA results in a small but significant dose reduction, without compromising CT angiogram diagnostic quality.

Key Points

? CT coronary angiography is performed to exclude the presence of significant coronary atherosclerosis. ? CT pulmonary angiography is performed to diagnose pulmonary thromboembolism. ? This retrospective study showed dose reduction by performing test bolus at 80 kVp. ? Diagnosis can be made with reduced exposure to ionising radiation.     

Quantification and characterisation of coronary artery plaque volume and adverse plaque features by coronary computed tomographic angiography: a direct comparison to intravascular ultrasound

Objective

We evaluated the performance of manual measures of coronary plaque volumes and atherosclerotic plaque features from coronary CT angiography (CTA), using intravascular ultrasound (IVUS) as the reference.

Methods

Thirty individual coronary plaques with suitable fiduciary markers were identified. Plaque volumes on coronary CTA were manually quantified by two observers and compared to IVUS plaque volumes as interpreted by an independent laboratory. The presence of adverse plaque characteristics—low attenuation plaque (LAP), positive remodelling (PR) and spotty calcification (SC)—on coronary CTA was evaluated and compared to IVUS.

Results

High correlation in plaque volumes was detected between observers (r?=?0.94, P?<?0.0001; 95 % limits of agreement <48.7 mm³, bias 6.6 mm³). Excellent correlation (r?=?0.95, P?<?0.0001) was noted in plaque volume between independent observers and IVUS (95 % limits of agreement <40.6 mm³, bias ?4.4 mm³) and did not differ from IVUS (105.0?±?56.7 vs. 109.4?±?60.7 mm³, P?=?0.2). The frequency of LAP (10 % vs. 17 %), PR (7 % vs. 10 %) and SC (27 % vs. 33 %) was similar between coronary CTA and IVUS (all P?=?NS).

Conclusions

Plaque volume on coronary CTA determined by manual methods demonstrates high correlation and modest agreement to IVUS. Further, coronary CTA demonstrates high accuracy for the identification of adverse plaque characteristics, including LAP, PR and SC.

Key Points

? Coronary CT angiography is a non-invasive test that enables coronary plaque assessment ? Plaque quantification by coronary CT angiography correlates well with intravascular ultrasound findings ? Coronary CT angiography can identify adverse plaque characteristics     

Methodological quality of diagnostic accuracy studies on non-invasive coronary CT angiography: influence of QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) items on sensitivity and specificity

Objectives

To evaluate the methodological quality of diagnostic accuracy studies on coronary computed tomography (CT) angiography using the QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) tool.

Methods

Each QUADAS item was individually defined to adapt it to the special requirements of studies on coronary CT angiography. Two independent investigators analysed 118 studies using 12 QUADAS items. Meta-regression and pooled analyses were performed to identify possible effects of methodological quality items on estimates of diagnostic accuracy.

Results

The overall methodological quality of coronary CT studies was merely moderate. They fulfilled a median of 7.5 out of 12 items. Only 9 of the 118 studies fulfilled more than 75 % of possible QUADAS items. One QUADAS item (“Uninterpretable Results”) showed a significant influence (P?=?0.02) on estimates of diagnostic accuracy with “no fulfilment” increasing specificity from 86 to 90 %. Furthermore, pooled analysis revealed that each QUADAS item that is not fulfilled has the potential to change estimates of diagnostic accuracy.

Conclusions

The methodological quality of studies investigating the diagnostic accuracy of non-invasive coronary CT is only moderate and was found to affect the sensitivity and specificity. An improvement is highly desirable because good methodology is crucial for adequately assessing imaging technologies.

Key Points

? Good methodological quality is a basic requirement in diagnostic accuracy studies. ? Most coronary CT angiography studies have only been of moderate design quality. ? Weak methodological quality will affect the sensitivity and specificity. ? No improvement in methodological quality was observed over time. ? Authors should consider the QUADAS checklist when undertaking accuracy studies.     

Staging of colorectal liver metastases after preoperative chemotherapy. Diffusion-weighted imaging in combination with Gd-EOB-DTPA MRI sequences increases sensitivity and diagnostic accuracy

Objectives

To compare the diagnostic accuracy and sensitivity of Gd-EOB-DTPA MRI and diffusion-weighted (DWI) imaging alone and in combination for detecting colorectal liver metastases in patients who had undergone preoperative chemotherapy.

Methods

Thirty-two consecutive patients with a total of 166 liver lesions were retrospectively enrolled. Of the lesions, 144 (86.8 %) were metastatic at pathology. Three image sets (1, Gd-EOB-DTPA; 2, DWI; 3, combined Gd-EOB-DTPA and DWI) were independently reviewed by two observers. Statistical analysis was performed on a per-lesion basis.

Results

Evaluation of image set 1 correctly identified 127/166 lesions (accuracy 76.5 %; 95 % CI 69.3–82.7) and 106/144 metastases (sensitivity 73.6 %, 95 % CI 65.6–80.6). Evaluation of image set 2 correctly identified 108/166 (accuracy 65.1 %, 95 % CI 57.3–72.3) and 87/144 metastases (sensitivity of 60.4 %, 95 % CI 51.9–68.5). Evaluation of image set 3 correctly identified 148/166 (accuracy 89.2 %, 95 % CI 83.4–93.4) and 131/144 metastases (sensitivity 91 %, 95 % CI 85.1–95.1). Differences were statistically significant (P?<?0.001). Notably, similar results were obtained analysing only small lesions (<1 cm).

Conclusions

The combination of DWI with Gd-EOB-DTPA-enhanced MRI imaging significantly increases the diagnostic accuracy and sensitivity in patients with colorectal liver metastases treated with preoperative chemotherapy, and it is particularly effective in the detection of small lesions.

Key Points

? Accurate detection of colorectal liver metastases is essential to determine resectability. ? Almost 80 % of patients are candidates for neoadjuvant chemotherapic treatment at diagnosis. After chemotherapy, metastases usually decrease, and drug-induced liver steatosis may be present. ? The sensitivity of imaging is significantly inferior to that in chemotherapy-naïve patients. ? DWI combined with Gd-EOB-DTPA increases sensitivity in detecting small metastases after chemotherapy.     

Diagnostic accuracy of two-dimensional shear wave elastography for the non-invasive staging of hepatic fibrosis in chronic hepatitis B: a cohort study with internal validation

Objectives

To determine the accuracy of two-dimensional shear wave elastography (2D-SWE) for noninvasive staging of hepatic fibrosis in chronic hepatitis B (CHB).

Methods

Patients with CHB infection who underwent liver biopsy were consecutively included. Receiver-operating characteristic (ROC) curves were constructed to assess the overall accuracy and identify optimal cutoff values.

Results

Three hundred three patients were analysed. The diagnostic performance characteristics were determined for the first 202 patients (the index cohort) and were validated on the next 101 patients (validation cohort). The areas under the ROC curves for significant fibrosis, severe fibrosis and cirrhosis were all greater than 0.90 and did not differ significantly between the index and validation cohorts. Using the cutoff values generated from the index cohort, the validation cohort 2D-SWE had negative predictive values of 82.6 % (95 % confidence interval [CI]: 68.4 %???92.3 %) for significant fibrosis, 95.1 % (95 % CI: 86.3 %???99.0 %) for severe fibrosis and 97.4 % (95 % CI: 90.8 %???99.7 %) for cirrhosis. The positive predictive values were 83.6 % (95 % CI: 71.2 %???92.2 %), 65.0 % (95 % CI: 48.1???79.5 %) and 60.0 % (95 % CI: 38.7 %???78.9 %), respectively.

Conclusion

The 2D-SWE showed good diagnostic accuracy in staging liver fibrosis in patients with CHB infection and assisted in excluding liver fibrosis and cirrhosis.

Key Points

? Two-dimensional shear wave elastography showed good diagnostic accuracy in assessing liver fibrosis. ? Diagnostic performance did not differ significantly between the index and validation cohorts. ? Two-dimensional shear wave elastography assisted in excluding liver fibrosis and cirrhosis.     

Protocol requirements and diagnostic value of PET/MR imaging for liver metastasis detection

Purpose

To compare the accuracy of PET/MR imaging with that of FDG PET/CT and to determine the MR sequences necessary for the detection of liver metastasis using a trimodality PET/CT/MR set-up.

Methods

Included in this single-centre IRB-approved study were 55 patients (22 women, age 61?±?11 years) with suspected liver metastases from gastrointestinal cancer. Imaging using a trimodality PET/CT/MR set-up (time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT, contrast-enhanced (CE) CT of the abdomen, and MR with T1-W/T2-W, diffusion-weighted (DWI), and dynamic CE imaging. Two readers evaluated the following image sets for liver metastasis: PET/CT (set A), PET/CECT (B), PET/MR including T1-W/T2-W (C), T1-W/T2-W with either DWI (D) or CE imaging (E), and a combination (F). The accuracy of each image set was determined by receiver-operating characteristic analysis using image set B as the standard of reference.

Results

Of 120 liver lesions in 21/55 patients (38 %), 79 (66 %) were considered malignant, and 63/79 (80 %) showed abnormal FDG uptake. Accuracies were 0.937 (95 % CI 89.5 – 97.9 %) for image set A, 1.00 (95 % CI 99.9 – 100.0 %) for set C, 0.998 (95 % CI 99.4 – 100.0 %) for set D, 0.997 (95 % CI 99.3 – 100.0 %) for set E, and 0.995 (95 % CI 99.0 – 100.0 %) for set F. Differences were significant for image sets D – F (P?<?0.05) when including lesions without abnormal FDG uptake. As shown by follow-up imaging after 50 – 177 days, the use of image sets D and both sets E and F led to the detection of metastases in one and three patients, respectively, and further metastases in the contralateral lobe in two patients negative on PET/CECT (P?=?0.06).

Conclusion

PET/MR imaging with T1-W/T2-W sequences results in similar diagnostic accuracy for the detection of liver metastases to PET/CECT. To significantly improve the characterization of liver lesions, we recommend the use of dynamic CE imaging sequences. PET/MR imaging has a diagnostic impact on clinical decision making.     

The value of diffusion-weighted imaging in the detection of prostate cancer: a meta-analysis

Objectives

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) as a single non-invasive method in detecting prostate cancer (PCa) and to deduce its clinical utility.

Methods

A systematic literature search was performed to identify relevant original studies. Quality of included studies was assessed by QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies). Data were extracted to calculate sensitivity and specificity as well as running the test of heterogeneity and threshold effect. The summary receiver operating characteristic (SROC) curve was drawn and area under SROC curve (AUC) served as a determination of the diagnostic performance of DWI for the detection of PCa.

Results

A total of 21 studies were included, with 27 subsets of data available for analysis. The pooled sensitivity and specificity with corresponding 95 % confidence interval (CI) were 0.62 (95 % CI 0.61–0.64) and 0.90 (95 % CI 0.89–0.90), respectively. Pooled positive likelihood ratio and negative likelihood ratio were 5.83 (95 % CI 4.61–7.37) and 0.30 (95 % CI 0.23–0.39), respectively. The AUC was 0.8991. Significant heterogeneity was observed. There was no notable publication bias.

Conclusions

DWI is an informative MRI modality in detecting PCa and shows moderately high diagnostic accuracy. General clinical application was limited because of the absence of standardized DW-MRI techniques.

Key points

? DWI provides incremental information for the detection and evaluation of PCa ? DWI has moderately high diagnostic accuracy in detecting PCa ? Patient condition, imaging protocols and study design positively influence diagnostic performance ? General clinical application requires optimization of image acquisition and interpretation     

Clinical evaluation of automatic tube voltage selection in chest CT angiography

Objective

To evaluate the clinical impact of automatic tube voltage selection on chest CT angiography (CTA).

Methods

Ninety-three patients were prospectively evaluated with a CT protocol aimed at comparing two successive CTAs acquired under similar technical conditions except for the kV selection: (1) the initial CTA was systematically obtained at 120 kVp and 90 ref mAs; (2) the follow-up CTA was obtained with an automatic selection of the kilovoltage (Care KV; Siemens Healthcare) for optimised CTA.

Results

At follow-up, 90 patients (97 %) underwent CTA with reduced tube voltage, 100 kV (n?=?26; 28 %) and 80 kV (n?=?64; 69 %), resulting in a significant dose-length-product reduction (follow-up: 87.27; initial: 141.88 mGy.cm; P?<?0.0001; mean dose reduction: 38.5 %) and a significant increase in the CNR at follow-up (follow-up: 11.5?±?3.5 HU; initial: 10.9?±?3.7 HU; P?=?0.03). The increase in objective image noise at follow-up (follow-up: 23.2?±?6.7 HU vs. 17.8?±?5.1 HU; P?<?0.0001) did not alter the diagnostic value of images.

Conclusion

Automatic tube voltage selection reduced the radiation dose delivered during chest CT angiograms by 38.5 % while improving the contrast-to-noise ratio of the examinations.

Key Points

? As low a dose as possible must be used for CT angiography. ? Automatic tube voltage selection permits reduced patient exposure. ? Lowering the kVp enables increased intravascular attenuation. ? Automatic tube voltage selection does not compromise the overall image quality.     

The role of capsule endoscopy after negative CT enterography in patients with obscure gastrointestinal bleeding

Objectives

The aim of the present study was to evaluate the role of capsule endoscopy in patients with obscure gastrointestinal bleeding (OGIB) after negative computed tomographic (CT) enterography.

Methods

We retrospectively included 30 patients with OGIB who received capsule endoscopy after negative CT enterography. The median age of the patients was 60?years, and 60% of patients were male. The median follow-up duration was 8?months. Overt bleeding was 60%, and occult bleeding was 40%.

Results

Based on capsule endoscopy results, a definitive diagnosis was made for 17 patients (57%): ulcer in nine patients (30%), active bleeding with no identifiable cause in five (17%), angiodysplasia in two (7%) and Dieulafoy’s lesion in one (3%). Two patients with jejunal ulcers were diagnosed with Crohn’s disease. Seven patients (41%) with positive capsule endoscopy received double balloon enteroscopy and two patients (12%) received steroid treatment for Crohn’s disease. Patients with overt bleeding, a previous history of bleeding, or who received large amounts of blood transfusions were more likely to show positive capsule endoscopy.

Conclusions

Capsule endoscopy showed high diagnostic yields in patients with OGIB after negative CT enterography and may help to provide further therapeutic plans for patients with OGIB and negative CT enterography.

Key Points

? CT enterography has been widely used in evaluating obscure gastrointestinal bleeding (OGIB). ? Capsule endoscopy showed high diagnostic yield for OGIB after negative CT enterography. ? Negative CT enterography does not exclude important causes of small bowel bleeding. ? Most lesions missed at CT-enterography are flat and can be detected by capsule endoscopy.     

The utilisation and diagnostic yield of radiological imaging in a specialist functional GI disorder clinic: an 11-year retrospective study

Objectives

The term functional gastrointestinal disorders (FGID) describes various aggregations of chronic gastrointestinal (GI) symptoms not explained by identifiable organic pathology; accordingly, their diagnosis rests on symptom-based criteria and a process of exclusion. Evidence is lacking on the appropriate use of abdominal imaging studies (AIS) in FGIDs.

Methods

We investigated the utilisation of AIS (site, modality, diagnostic yield/significance) at a tertiary FGID clinic over an 11-year period.

Results

Of 1,621 patients, 507 (31 %; 67.5 % women, mean age 43.9?±?17.37 years) referred from primary care had 997 AIS (1.7 per patient): ultrasonography (US) 36.1 %, fluoroscopy (FLS) 28.8 %, computed tomography (CT) 19.6 %, plain radiography (PR) 13.5 %, nuclear medicine (NM) 1 %). Of the 997 AIS, 55.6 % (554/997) were normal. Of the AIS with positive findings, 9.9 % (62/625) were deemed ‘probably significant’ and 14.7 % (92/625) ‘significant’. Of the CT and FLS studies, 12.3 % and 13.6 %, respectively, yielded ‘significant’ abnormalities compared to 2.2 % of the US studies and 2.1 % of the PR studies. CT identified five of seven neoplasms, associated with male sex, increasing age and symptom onset after age 50 years.

Conclusions

This study confirmed low use of AIS in tertiary FGID clinics and a high proportion of normal studies. Barium swallow/meal and CT were more likely to identify ‘probably significant’ or ‘significant’ findings, including neoplasms.

Key Points

? Imaging referral rates from a specialist functional gastrointestinal disorder clinic are low ? Despite this, normal studies are still frequent in those who are imaged ? Ultrasonography was the most frequent investigation, yet yielded significant findings infrequently ? Abdominal radiographs accounted for 13.5 % of investigations yet were normal in 71.8 % ? CT and fluoroscopy were more likely to yield positive findings     

Diagnostic performance of shear wave elastography in the identification of malignant thyroid nodules: a meta-analysis

Objective

This meta-analysis aimed to assess the performance of shear wave elastography (SWE) in the identification of malignant thyroid nodules.

Methods

Web of Science, Scopus, PubMed, and the references of narrative reviews were searched for relevant studies with a publication date through October 2013. The methodological quality was assessed using QUADAS tools. Data synthesis was calculated using the bivariate mixed-effects regression model.

Results

Of the 131 studies identified, 15 (11.5 %) were included, in which SWE, point-SWE or 2D SWE, was used to evaluate 1,867 thyroid nodules in 1,525 patients. Methodological assessment revealed study quality was moderate to high. The pooled sensitivity, specificity, and area under the summary receiver operating characteristic curve of SWE for detecting malignant thyroid nodules were 84.3 % (95 % confidence interval [CI], 76.9–89.7 %), 88.4 % (95 % CI, 84.0–91.7 %), and 93 % (95 % CI, 90–95 %), respectively. As a screening tool, positive and negative predictive values were 27.7–44.7 % and 98.1–99.1 %, respectively, calculated with a malignance prevalence of 5–10 % in thyroid nodules. A publication bias regression test revealed no significant small-study bias.

Conclusions

SWE is a highly accurate diagnostic modality for the identification of malignant thyroid nodules, with promise for integration into routine imaging protocols for thyroid nodules.

Key Points

? Shear wave elastography (SWE) is a group of novel ultrasound-based technologies. ? Meta-analysis was employed to assess relevant studies of SWE of thyroid nodules. ? SWE had high sensitivity and specificity in identifying malignant thyroid nodules. ? The high negative predictive value of SWE can reduce unnecessary biopsies.     

Clinical examination versus magnetic resonance imaging in the pretreatment staging of cervical carcinoma: systematic review and meta-analysis

Objectives

To review the literature on the diagnostic performance of clinical examination and magnetic resonance imaging (MRI) in detecting parametrial invasion and advanced stage disease (FIGO stage ≥ IIB) in patients with cervical carcinoma.

Methods

Reports of studies were searched using the MEDLINE, EMBASE and Cochrane databases. Two observers reported on data relevant for analysis and methodological quality using the QUADAS scoring system. Publication bias was analysed using Deeks funnel plots. Covariates were added to the model to study the influence on the summary results of the technical and methodological aspects of the clinical examination and MRI.

Results

In total, 3,254 patients were included. Partial verification bias was often encountered. Pooled sensitivity was 40 % (95 % CI 25–58) for the evaluation of parametrial invasion with clinical examination and 84 % (95 % CI 76–90) with MRI, 53 % (95 % CI 41–66) for the evaluation of advanced disease with clinical examination, and 79 % (95 % CI 64–89) with MRI. Pooled specificities were comparable between clinical examination and MRI. Different technical aspects of MRI influenced the summary results.

Conclusions

MRI is significantly better than clinical examination in ruling out parametrial invasion and advanced disease in patients with cervical carcinoma.

Key Points

? MRI has a higher sensitivity than clinical examination for staging cervical carcinoma. ? Clinical examination and MRI have comparably high specificity for staging cervical carcinoma. ? Quality of clinical examination studies was lower than that of MRI studies. ? The use of newer MRI techniques positively influences the summary results. ? Anaesthesia during clinical examination positively influences the summary results.