Percutaneous transthoracic needle biopsy of small (≤1 cm) lung nodules under C-arm cone-beam CT virtual navigation guidance

Objectives

To describe our initial experience with percutaneous transthoracic needle biopsy (PCNB) of small (≤1 cm) lung nodules using a cone-beam computed tomography (CBCT) virtual navigation guidance system in 105 consecutive patients.

Methods

One hundred and five consecutive patients (55 male, 50 female; mean age, 62 years) with 107 small (≤1 cm) lung nodules (mean size, 0.85 cm?±?0.14) underwent PCNBs under CBCT virtual-navigation guidance system and constituted our study population. Procedural details—including radiation dose, sensitivity, specificity, diagnostic accuracy and complication rates of CBCT virtual navigation guided PCNBs—were described.

Results

The mean number of pleural passages with the coaxial needle, biopsies, CT acquisitions, total procedure time, coaxial introducer dwelling time, and estimated radiation exposure during PCNBs were 1.03?±?0.21, 3.1?±?0.7, 3.4?±?1.3, 10.5 min?±?3.2 and 7.2 min?±?2.5, and 5.72 mSv?±?4.19, respectively. Sixty nodules (56.1 %) were diagnosed as malignant, 38 (35.5 %) as benign and nine (8.4 %) as indeterminate. The sensitivity, specificity, and diagnostic accuracy of CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules were 96.7 % (58/60), 100 % (38/38) and 98.0 % (96/98), respectively. Complications occurred in 13 (12.1 %) cases; pneumothorax in seven (6.5 %) and haemoptysis in six (5.6 %).

Conclusion

CBCT virtual-navigation-guided PCNB is a highly accurate and safe diagnostic method for small (≤1 cm) nodules.

Key Points

? CBCT virtual-navigation guidance offers new biopsy options for lung nodules ? CBCT virtual-navigation-guided PCNB is highly accurate for small (≤1 cm) nodules ? CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules is safe ? Procedure time and radiation exposure of CBCT virtual-navigation-guided PCNB is reasonable     

Prospectively ECG-triggered high-pitch spiral acquisition for coronary CT angiography using dual source CT: technique and initial experience

Objective

We evaluated radiation exposure and image quality of a new coronary CT angiography protocol, high-pitch spiral acquisition, using dual source CT (DSCT).

Material and methods

Coronary CTA was performed in 25 consecutive patients with a stable heart rate of 60 bpm or less after premedication, using 2?×?128 0.6-mm sections, 38.4-mm collimation width and 0.28-s rotation time. Tube settings were 100 kV/320 mAs and 120 kV/400 mAs for patients below and above 100-kg weight, respectively. Data acquisition was prospectively ECG-triggered at 60% of the R–R interval using a pitch of 3.2 (3.4 for the last 10 patients). Images were reconstructed with 75-ms temporal resolution, 0.6-mm slice thickness and 0.3-mm increment. Image quality was evaluated using a four-point scale (1 = excellent, 4 = unevaluable).

Results

Mean range of data acquisition was 113?±?22 mm, mean duration was 268?±?23 ms. Of 363 coronary artery segments, 327 had an image quality score of 1, and only 2 segments were rated as “unevaluable”. Mean dose–length product (DLP) was 71?±?23 mGy cm, mean effective dose was 1.0?±?0.3 mSv (range 0.78–2.1 mSv). For 21 patients with a body weight below 100 kg, mean DLP was 63?±?5 mGy cm (0.88?±?0.07 mSv; range 0.78–0.97 mSv).

Conclusion

Prospectively ECG-triggered high-pitch spiral CT acquisition provides high and stable image quality at very low radiation dose.     

Low-dose CT of the lung: potential value of iterative reconstructions

Objectives

To prospectively assess the impact of sinogram-affirmed iterative reconstruction (SAFIRE) on image quality of nonenhanced low-dose lung CT as compared to filtered back projection (FBP).

Methods

Nonenhanced low-dose chest CT (tube current-time product: 30?mAs) was performed on 30 patients at 100?kVp and on 30 patients at 80?kVp. Images were reconstructed with FBP and SAFIRE. Two blinded, independent readers measured image noise; two readers assessed image quality of normal anatomic lung structures on a five-point scale. Radiation dose parameters were recorded.

Results

Image noise in datasets reconstructed with FBP (57.4?±?15.9) was significantly higher than with SAFIRE (31.7?±?9.8, P?<?0.001). Image quality was significantly superior with SAFIRE than with FBP (P?<?0.01), without significant difference between FBP at 100?kVp and SAFIRE at 80?kVp (P?=?0.68). Diagnostic image quality was present with FBP in 96% of images at 100?kVp and 88% at 80?kVp, and with SAFIRE in 100% at 100?kVp and 98% at 80?kVp. There were significantly more datasets with diagnostic image quality with SAFIRE than with FBP (P?<?0.01). Mean CTDI_vol and effective doses were 1.5?±?0.7?mGy·cm and 0.7?±?0.2?mSv at 100?kVp, and 1.4?±?2.8?mGy·cm and 0.5?±?0.2?mSv at 80?kVp (P?<?0.001, both).

Conclusions

Use of SAFIRE in low-dose lung CT reduces noise, improves image quality, and renders more studies diagnostic as compared to FBP.

Key Points

? Low-dose computed tomography is an important thoracic investigation tool. ? Radiation dose can be less than 1?mSv with iterative reconstructions. ? Iterative reconstructions render more low-dose lung CTs diagnostic compared to conventional reconstructions.     

CT perfusion technique for assessment of early kidney allograft dysfunction: preliminary results

Objectives

To assess the benefit of quantitative computed tomography (CT) perfusion for differentiating acute tubular necrosis (ATN) and acute rejection (AR) in kidney allografts.

Methods

Twenty-two patients with acute kidney allograft dysfunction caused by either AR (n?=?6) or ATN (n?=?16) were retrospectively included in the study. All patients initially underwent a multiphase CT angiography (CTA) protocol (12 phases, one phase every 3.5 s) covering the whole graft to exclude acute postoperative complications. Multiphase CT dataset and dedicated software were used to calculate renal blood flow. Renal biopsy or clinical course of disease served as the standard of reference. Mean effective radiation dose and mean amount of contrast media were calculated.

Results

Renal blood flow values were significantly lower (P?=?0.001) in allografts undergoing AR (48.3?±?21 ml/100 ml/min) compared with those with ATN (77.5?±?21 ml/100 ml/min). No significant difference (P?=?0.71) was observed regarding creatinine level with 5.65?±?3.1 mg/dl in AR and 5.3?±?1.9 mg/dl in ATN. The mean effective radiation dose of the CT perfusion protocol was 13.6?±?5.2 mSv; the mean amount of contrast media applied was 34.5?±?5.1 ml. All examinations were performed without complications.

Conclusion

CT perfusion of kidney allografts may help to differentiate between ATN and rejection.

Key points

? Quantitative CT perfusion of renal transplants is feasible. ? CT perfusion could help to non-invasively differentiate AR from ATN. ? CT perfusion might make some renal biopsies unnecessary.     

Image noise-based dose adaptation in dynamic volume CT of the heart: dose and image quality optimisation in comparison with BMI-based dose adaptation

Objectives

To compare the image quality and radiation dose using image-noise (IN)-based determination of X-ray tube settings compared with a body mass index (BMI)-based protocol during CT coronary angiography (CTCA).

Methods

Two hundred consecutive patients referred for CTCA to our institution were divided into two groups: BMI-based, 100 patients had CTCA with the X-ray tube current adjusted to the patient’s BMI while maintaining a fixed tube potential of 120 kV; IN-based, 100 patients underwent imaging with the X-ray tube current and voltage adjusted to the IN measured within the mid-left ventricle on a pre-acquisition trans-axial image. Two independent cardiac radiologists performed blinded image quality assessment with quantification of the IN and signal-to-noise ratio (SNR) from the mid-LV and qualitative assessment using a three-point score. Radiation dose (CTDI and DLP) was recorded from the console.

Results

Results showed: IN (HU): BMI-based, 30.1?±?9.9; IN-based, 33.1?±?6.7; 32 % variation reduction (P?=?0.001); SNR: BMI-based, 18.6?±?7.1; IN-based, 15.4?±?3.7; 48 % variation reduction (P?<?0.0001). Visual scores: BMI-based, 2.3?±?0.6; IN-based, 2.2?±?0.5 (P?=?0.54). Radiation dose: CTDI (mGy), BMI-based, 22.68?±?8.9; IN-based, 17.16?±?7.6; 24.3 % reduction (P?<?0.001); DLP (mGy.cm), BMI-based, 309.3?±?127.5; IN-based, 230.6?±?105.5; 25.4 % reduction (P?<?0.001).

Conclusions

Image-noise-based stratification of X-ray tube parameters for CTCA results in 32 % improvement in image quality and 25 % reduction in radiation dose compared with a BMI-based protocol.

Key Points

? Image quality and radiation dose are closely related in CT coronary angiography. ? So too are the image quality, radiation dose and body mass index (BMI). ? An image-noise-based CTCA protocol reduces the radiation dose by 25 %. ? It improves inter-patient image homogeneity by 32 %.     

Impact of organ-specific dose reduction on the image quality of head and neck CT angiography

Objectives

Organ-specific dose reduction (OSDR) algorithms can reduce radiation on radiosensitive organs up to 59 %. This study evaluates the influence of a new OSDR algorithm on image quality of head and neck computed tomographic angiography (CTA) in clinical routine.

Methods

Sixty-two consecutive patients (68?±?13 years) were randomised into two groups and imaged using 128-row multidetector CT. Group A (n?=?31) underwent conventional CTA and group B (n?=?31) CTA with a novel OSDR algorithm. Subjective and objective image quality were statistically compared. Subjective image quality was rated on a five-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated with region-of-interest measurements.

Results

The SNR of the common carotid artery and middle cerebral artery was 53.6?±?22.7 and 43.3?±?15.3 (group A) versus 54.1?±?20.5 and 46.2?±?14.6 (group B). The CNR was 40.0?±?19.3 and 29.7?±?12.0 (group A) compared with 40.7?±?16.8 and 32.9?±?10.9 (group B), respectively. Subjective image quality was excellent in both groups (mean score 4.4?±?0.7 versus 4.4?±?0.6). Differences between the two groups were not significant.

Conclusions

The novel OSDR algorithm does not compromise image quality of head and neck CTA. Its application can be recommended for CTA in clinical routine to protect the thyroid gland and ocular lenses from unnecessary high radiation.

Key Points

? Organ-specific dose reduction (OSDR) can significantly reduce radiation exposure during CT ? OSDR does not compromise image quality of head and neck CTA ? OSDR can significantly lower the risk of radiation damage to sensitive organs ? OSDR can easily be applied in routine clinical practice     

Single-portal-phase low-tube-voltage dual-energy CT for short-term follow-up of acute pancreatitis: evaluation of CT severity index,interobserver agreement and radiation dose

Objectives

To intra-individually compare single-portal-phase low-tube-voltage (100-kVp) computed tomography (CT) with 120-kVp images for short-term follow-up assessment of CT severity index (CTSI) of acute pancreatitis, interobserver agreement and radiation dose.

Methods

We retrospectively analysed 66 patients with acute pancreatitis who underwent initial dual-contrast-phase CT (unenhanced, arterial, portal phase) at admission and short-term (mean interval 11.4 days) follow-up dual-contrast-phase dual-energy CT. The 100-kVp and linearly blended images representing 120-kVp acquisition follow-up CT images were independently evaluated by three radiologists using a modified CTSI assessing pancreatic inflammation, necrosis and extrapancreatic complications. Scores were compared with paired t test and interobserver agreement was evaluated using intraclass correlation coefficients (ICC).

Results

Mean CTSI scores on unenhanced, portal- and dual-contrast-phase images were 4.9, 6.1 and 6.2 (120 kVp) and 5.0, 6.0 and 6.1 (100 kVp), respectively. Contrast-enhanced series showed a higher CTSI compared to unenhanced images (P?P?>?0.7). CTSI scores were comparable for 100-kVp and 120-kVp images (P?>?0.05). Interobserver agreement was substantial for all evaluated series and subcategories (ICC 0.67–0.93). DLP of single-portal-phase 100-kVp images was reduced by 41 % compared to 120-kVp images (363.8 versus 615.9 mGy cm).

Conclusions

Low-tube-voltage single-phase 100-kVp CT provides sufficient information for follow-up evaluation of acute pancreatitis and significantly reduces radiation exposure.

Key Points

? Single-portal-phase CT provides sufficient evaluation for follow-up of acute pancreatitis. ? Follow-up CT does not benefit from unenhanced or arterial-phase acquisition. ? CT severity index scores are equal for dual-contrast-phase 100-/120-kVp acquisition (P?>?0.05). ? 100-kVp single-portal-phase follow-up CT of acute pancreatitis significantly reduces radiation exposure.     

Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

Objective

To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol.

Methods

100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated.

Results

Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P?<?0.001). Effective dose was 4.29?±?1.86 and 11.95?±?5.34 mSv for each of the two protocols (P?<?0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging.

Conclusion

In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality.

Key Points

? Coronary computed tomographic angiography (CCTA) can be difficult in patients with arrhythmias. ? Prospectively ECG-triggered sequential CCTA is feasible in patients with atrial fibrillation. ? Prospective sequential imaging can improve quality compared with retrospective analysis. ? Prospective sequential imaging decreases radiation exposure by 64 % compared with retrospective mode.     

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.     

Image quality assessment of ultra low-dose chest CT using sinogram-affirmed iterative reconstruction

Objectives

To assess the image quality of ultra-low-dose computed tomography (ULDCT) using sinogram-affirmed iterative reconstruction (SAFIRE) compared to reduced dose CT (RDCT).

Methods

Eighty-one consecutive patients underwent non-enhanced ULDCT using 80 kVp and 30 mAs and contrast-enhanced RDCT using automated tube potential selection and tube current modulation. CT images were reconstructed with SAFIRE. Image noise and subjective image quality of normal structures and various pulmonary lesions were assessed.

Results

The mean effective doses were 0.29?±?0.03 and 2.88?±?1.11 mSv for ULDCT and RDCT, respectively. ULDCT had significantly higher noise (p?<?0.001). Image quality of five normal structures was diagnostic in 91.1 % of ULDCT and 100 % of RDCT. With ULDCT, the frequencies of non-diagnostic image quality were 2.0 (1/50), 4.6 (13/280), 25.5 (14/55), and 40.0 (8/20)% for BMIs of?<?20, 20–25, 25–30, and >30. In the assessment of pulmonary lesions, non-diagnostic image quality was observed for 11.2 % of all lesions, 60.9 % of decreased attenuation (significantly more frequent for upper lung lesions), and 23.5 % of ground-glass nodules.

Conclusion

ULDCT generates diagnostic images in patients with a BMI ≤25, but is of limited use for lesions with decreased attenuation, ground-glass nodules, or those located in the upper lobe.

Key Points

? Iterative reconstruction enables ultra-low-dose CT (ULDCT) with very low radiation doses. ? Image quality of ULDCT depends on the patient body mass index (BMI). ? Selection of kVp and mAs depends on both BMI and lesion type. ? Diagnosis of pulmonary emphysema or ground-glass nodules requires higher radiation doses.     

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.     

Clinical impact of hyperattenuation of adrenal glands on contrast-enhanced computed tomography of polytraumatised patients

Objective

To evaluate the prognostic value of hyperattenuating adrenal glands on contrast-enhanced CT of polytraumatised patients.

Methods

Two hundred ninety-two patients (195 men and 97 women, mean age 45.3?±?23.3 years) were included in this retrospective study. CT examinations were performed 60 s after intravenous injection of contrast material. Image analysis was performed by two radiologists. Patients were assigned to one of two groups according to the attenuation of the adrenal gland [group 1: adrenal glands ≥ inferior vena cava (IVC); group 2: adrenal glands < IVC].

Results

Eighteen patients (42.2 years?±?24.2) were assigned to group 1 and 274 patients (48.4 years?±?22.4) to group 2. The average adrenal density was 150.8?±?36.1 HU in group 1 and 83.7?±?23.6 HU in group 2 (P?<?0.0001). Eight of the 18 patients in group 1 (44.4 %) and 33 of the 274 patients in group 2 (12.4 %) died during hospitalisation (P?<?0.05). Mean adrenal enhancement was significantly higher in patients who died (101.9?±?40.6 HU) compared with survivors (86.1?±?27.0 HU; P?<?0.001).

Conclusion

Hyperattenuation of adrenal glands is associated with a higher mortality rate in polytraumatised patients and may serve as a predictor of poor clinical outcome.

Key points

? Hyperattenuating adrenal glands can be observed in 6.2 % of polytraumatised patients. ? Hyperattenuating adrenal glands indicate poor clinical outcome in polytraumatised patients. ? In polytraumatised patients, hyperattenuating adrenal glands are associated with a high mortality rate. ? Adrenal enhancement is higher amongst patients who died than amongst survivors.     

Computed tomography angiography of carotid and coronary artery via a single-bolus injection protocol: a feasibility study using 320-row multidetector CT

Objectives

To investigate the feasibility of using a single-dose injection protocol in CT angiography (CTA) of the carotid and coronary artery with 320-row multidetector CT.

Methods

A total of 82 consecutive patients with suspected carotid artery disease underwent an original CTA protocol aiming at capturing the extra-cranial carotid arteries and coronary arteries simultaneously using 320-row MDCT. The image quality, attenuation, and CNRs of the carotid and coronary arteries were assessed. The lag time (between two separated volumetric acquisitions) was compared between patients with and without cardiac venous opacification (CVO). The contrast medium volume and radiation dose were recorded.

Results

The image quality was 99.4 % diagnostic in carotid and 86.9 % in coronary artery segments. The mean attenuation of carotid and coronary arteries ranged from 462.2 Hu to 533.7 Hu, 415.9 Hu to 454.7 Hu respectively. The mean CNR of the carotid and coronary artery ranged from 15.8 to 18.9 and 17.7 to 20.4 respectively. The lag time in patients with and without CVO was 5.75?±?1.64 s vs. 4.21?±?1.14 s (p?<?0.05). The mean radiation dose was 6.6?±?4.1 mSv.The mean contrast media volume was 71.9?±?9.1 ml.

Conclusions

The carotid and coronary artery can be imaged simultaneously via our original single-dose injection CTA protocol using 320-row CT with adequate image quality.

Key Points

? Carotid and coronary 320-row CTA can be achieved in a single-dose injection. ? Longer coverage was achieved with two or more volumes using 320-row CT. ? The single-dose protocol allows a reduced contrast agent dose of about 72 ml.     

Quantitative assessment of right ventricular function and pulmonary regurgitation in surgically repaired tetralogy of Fallot using 256-slice CT: comparison with 3-Tesla MRI

Objectives

To compare 256-slice cardiac computed tomography (CCT) with cardiac magnetic resonance (CMR) imaging to assess right ventricular (RV) function and pulmonary regurgitant fraction (PRF) in patients with repaired tetralogy of Fallot (TOF).

Methods

Thirty-three consecutive patients with repaired TOF underwent retrospective ECG-gated CCT and 3-Tesla CMR. RV and left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were measured using CCT and CMR. PRF-CCT (%) was defined as (RVSV???LVSV)/RVSV. PRF-CMR (%) was measured by the phase-contrast method. Repeated measurements were performed to determine intra- and interobserver variability.

Results

CCT measurements, including PRF, correlated highly with the CMR reference (r?=?0.71–0.96). CCT overestimated RVEDV (mean difference, 17.1?±?2.9 ml), RVESV (12.9?±?2.1 ml) and RVSV (4.2?±?2.0 ml), and underestimated RVEF (?2.6?±?1.0 %) and PRF (?9.1?±?2.0 %) compared with CMR. The limits of agreement between CCT and CMR were in a good range for all measurements. The variability in CCT measurements was lower than those in CMR. The estimated effective radiation dose was 7.6?±?2.6 mSv.

Conclusions

256-slice CCT can assess RV function and PRF with relatively low dose radiation exposure in patients with repaired TOF, but overestimates RV volume and underestimates PRF.

Key points

? 256-slice CT assessment of RV function is highly reproducible in repaired TOF. ? Pulmonary regurgitation can be evaluated by biventricular systolic volume difference. ? CT overestimates RV volume and underestimates pulmonary regurgitation, compared with MRI.     

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.     

MR-guided facet joint injection therapy using an open 1.0-T MRI system: an outcome study

Objectives

To evaluate the accuracy, safety and efficacy of magnetic resonance imaging (MRI)-guided facet joint injection therapy using a 1.0-T open MRI.

Methods

One hundred and sixty-six facet joint blocks in 45 patients with lower back pain were performed under MR fluoroscopic guidance using a proton-density-weighted turbo-spin-echo sequence. An in-room monitor, wireless MR-mouse for operator-controlled multiplanar navigation, a flexible surface coil and MR-compatible 20-G needle were used. Clinical outcome was evaluated by questionnaire before intervention and after 1 week, 3, 6 and 12 months using a numerical visual analogue scale (VAS).

Results

All facet joint blocks were considered technically successful with distribution of the injectant within and/or around the targeted facet joint. No major complications occurred. The final outcome analysis included 38 patients. An immediate effect was reported by 63 % of the patients. A positive mid-/long-term effect was seen in 13 patients (34 %) after 6 months and in 9 patients (24 %) after 12 months. Mean VAS was reduced from 7.1?±?1.7 (baseline) to 3.5?±?2.2, 4.1?±?3.0, 3.8?±?2.9 and 4.6?±?2.9 at 1 week, 3, 6 and 12 months (P?<?0.01).

Conclusions

MR-guided facet joint injection therapy of the lumbosacral spine is accurate, safe and efficient in the symptomatic treatment of lower back pain.

Key Points

? MR-guided facet joint infiltration provides an alternative to CT and conventional fluoroscopy. ? Clinical outcomes are comparable with conventional fluoroscopy and CT-guided facet joint interventions. ? Ionising radiation can be avoided for both patient and physician. ? MR-guided facet joint injection provides safe and effective treatment of back pain.     

PET-based delineation of tumour volumes in lung cancer: comparison with pathological findings

Purpose

The objective of the study was to validate an adaptive, contrast-oriented thresholding algorithm (COA) for tumour delineation in ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for non-small cell lung cancer (NSCLC) in comparison with pathological findings. The impact of tumour localization, tumour size and uptake heterogeneity on PET delineation results was also investigated.

Methods

PET tumour delineation by COA was compared with both CT delineation and pathological findings in 15 patients to investigate its validity. Correlations between anatomical volume, metabolic volume and the pathology reference as well as between the corresponding maximal diameters were determined. Differences between PET delineations and pathological results were investigated with respect to tumour localization and uptake heterogeneity.

Results

The delineated volumes and maximal diameters measured on PET and CT images significantly correlated with the pathology reference (both r?>?0.95, p?<?0.0001). Both PET and CT contours resulted in overestimation of the pathological volume (PET 32.5?±?26.5 %, CT 46.6?±?27.4 %). CT volumes were larger than those delineated on PET images (CT 60.6?±?86.3 ml, PET 48.3?±?61.7 ml). Maximal tumour diameters were similar for PET and CT (51.4?±?19.8 mm for CT versus 53.4?±?19.1 mm for PET), slightly overestimating the pathological reference (mean difference CT 4.3?±?3.2 mm, PET 6.2?±?5.1 mm). PET volumes of lung tumours located in the lower lobe were significantly different from those determined from pathology (p?=?0.037), whereas no significant differences were observed for tumours located in the upper lobe (p?=?0.066). Only minor correlation was found between pathological tumour size and PET heterogeneity (r?=??0.24).

Conclusion

PET tumour delineation by COA showed a good correlation with pathological findings. Tumour localization had an influence on PET delineation results. The impact of tracer uptake heterogeneity on PET delineation should be considered carefully and individually in each patient. Altogether, PET tumour delineation by COA for NSCLC patients is feasible and reliable with the potential for routine clinical application.     

Cardiac valve calcifications on low-dose unenhanced ungated chest computed tomography: inter-observer and inter-examination reliability,agreement and variability

Objectives

To determine inter-observer and inter-examination variability for aortic valve calcification (AVC) and mitral valve and annulus calcification (MC) in low-dose unenhanced ungated lung cancer screening chest computed tomography (CT).

Methods

We included 578 lung cancer screening trial participants who were examined by CT twice within 3 months to follow indeterminate pulmonary nodules. On these CTs, AVC and MC were measured in cubic millimetres. One hundred CTs were examined by five observers to determine the inter-observer variability. Reliability was assessed by kappa statistics (κ) and intra-class correlation coefficients (ICCs). Variability was expressed as the mean difference ± standard deviation (SD).

Results

Inter-examination reliability was excellent for AVC (κ?=?0.94, ICC?=?0.96) and MC (κ?=?0.95, ICC?=?0.90). Inter-examination variability was 12.7?±?118.2 mm³ for AVC and 31.5?±?219.2 mm³ for MC. Inter-observer reliability ranged from κ?=?0.68 to κ?=?0.92 for AVC and from κ?=?0.20 to κ?=?0.66 for MC. Inter-observer ICC was 0.94 for AVC and ranged from 0.56 to 0.97 for MC. Inter-observer variability ranged from -30.5?±?252.0 mm³ to 84.0?±?240.5 mm³ for AVC and from -95.2?±?210.0 mm³ to 303.7?±?501.6 mm³ for MC.

Conclusions

AVC can be quantified with excellent reliability on ungated unenhanced low-dose chest CT, but manual detection of MC can be subject to substantial inter-observer variability. Lung cancer screening CT may be used for detection and quantification of cardiac valve calcifications.

Key points

? Low-dose unenhanced ungated chest computed tomography can detect cardiac valve calcifications. ? However, calcified cardiac valves are not reported by most radiologists. ? Inter-observer and inter-examination variability of aortic valve calcifications is sufficient for longitudinal studies. ? Volumetric measurement variability of mitral valve and annulus calcifications is substantial.     

Contrast agent bolus tracking with a fixed threshold or a manual fast start for coronary CT angiography

Objectives

Comparison of bolus tracking with a fixed threshold versus a manual fast start for coronary CT angiography.

Methods

We retrospectively analysed 320-row coronary CT angiography of 50 patients with suspected or known coronary artery disease. Twenty-five examinations were initiated by a bolus tracking method (group 1), 25 examinations with a manual fast surestart (group 2).

Results

Mean attenuation values in the ascending aorta were 519?±?111 Hounsfield units (HU) in group 1 and 476?±?65 HU in group 2 (p?=?0.10). Assessable vessel lengths were 171?±?44 mm vs 172?±?29 mm for the right coronary artery (p?=?0.91), 11?±?4 mm vs 12?±?4 mm for the left main (p?=?0.9), 163?±?28 mm vs 151?±?26 mm for the left anterior descending coronary artery (p?=?0.11) and 125?±?41 mm vs 110?±?37 mm for the left circumflex coronary artery (p?=?0.18). Image quality for all coronary arteries was not significantly different between the groups (p?>?0.41). The attenuation ratio between the left and right ventricle was 2.8?±?0.7 vs 3.6?±?1.0 (p?=?0.003). Significantly less contrast agent was used in group 2 (64?±?6 ml vs 80?±?0 ml; p?<?0.001).

Conclusions

Bolus tracking with a fixed threshold and with a manual fast start are both suitable methods; the fast start allowed a reduction of contrast agent volumes.

Key Points

? Fixed threshold bolus tracking is suitable for coronary 320-row CT angiography ? Manual fast start bolus tracking can reduce contrast agent volumes ? Manual fast start and fixed threshold initiation achieve good image quality ? Fixed threshold bolus tracking achieves a more reliable contrast bolus position