Percutaneous lung biopsies: performance of an optical CT-based navigation system with a low-dose protocol

Objectives

To compare patients’ radiation exposure, technical feasibility, imaging quality and complication rate of percutaneous lung biopsies (PLBs) performed with a low-dose (LD) CT protocol under guidance of an optical navigation system.

Methods

Fifty-two consecutive patients with suspected malignant lung lesions were enrolled and randomised into group 1 (PLBs under the guidance of the navigation system) and group 2 (PLBs under the guidance navigation system with an LD protocol). Patients’ demographics, lesion features, procedure-related variables and CT image quality for group 2 were recorded and compared.

Results

Technical success was 100 % in both groups. The radiation dose to patients’ chest was significantly lower in group 2 than in group 1 (group 1: mean TDLP 206?±?59 mGy·cm, ~ 3.5?±?1.0 mSv; group 2: 54.2?±?46.2 mGy·cm, ~ 0.92?±?0.78 mSv; P?<?0.0001). The PNX rate was 12 % in group 1 and 11.1 % in group 2. The haemoptysis rate was 8.0 % in group 1 and 3.7 % in group 2. CT image quality obtained in group 2 was always rated as adequate and as excellent in 15 cases (56.0 %).

Conclusions

An optical navigation system with LD CT protocol is useful for performing lung biopsies with decreased patient radiation exposure.

Key Points

? Navigation systems are useful tools in percutaneous imaging-guided procedures. ? For lung biopsies, low-dose (LD) CT protocols may be used. ? Combining LD protocols with optical CT navigation results in significantly reduced radiation exposure.     

Comparison of integrated whole-body [11C]choline PET/MR with PET/CT in patients with prostate cancer

Purpose

To evaluate the performance of conventional [¹¹C]choline PET/CT in comparison to that of simultaneous whole-body PET/MR.

Methods

The study population comprised 32 patients with prostate cancer who underwent a single-injection dual-imaging protocol with PET/CT and subsequent PET/MR. PET/CT scans were performed applying standard clinical protocols (5 min after injection of 793?±?69 MBq [¹¹C]choline, 3 min per bed position, intravenous contrast agent). Subsequently (52?±?15 min after injection) PET/MR was performed (4 min per bed position). PET images were reconstructed iteratively (OSEM 3D), scatter and attenuation correction of emission data and regional allocation of [¹¹C]choline foci were performed using CT data for PET/CT and segmented Dixon MR, T1 and T2 sequences for PET/MR. Image quality of the respective PET scans and PET alignment with the respective morphological imaging modality were compared using a four point scale (0–3). Furthermore, number, location and conspicuity of the detected lesions were evaluated. SUVs for suspicious lesions, lung, liver, spleen, vertebral bone and muscle were compared.

Results

Overall 80 lesions were scored visually in 29 of the 32 patients. There was no significant difference between the two PET scans concerning number or conspicuity of the detected lesions (p not significant). PET/MR with T1 and T2 sequences performed better than PET/CT in anatomical allocation of lesions (2.87?±?0.3 vs. 2.72?±?0.5; p?=?0.005). The quality of PET/CT images (2.97?±?0.2) was better than that of the respective PET scan of the PET/MR (2.69?±?0.5; p?=?0.007). Overall the maximum and mean lesional SUVs exhibited high correlations between PET/CT and PET/MR (ρ?=?0.87 and ρ?=?0.86, respectively; both p?<?0.001).

Conclusion

Despite a substantially later imaging time-point, the performance of simultaneous PET/MR was comparable to that of PET/CT in detecting lesions with increased [¹¹C]choline uptake in patients with prostate cancer. Anatomical allocation of lesions was better with simultaneous PET/MR than with PET/CT, especially in the bone and pelvis. These promising findings suggest that [¹¹C]choline PET/MR might have a diagnostic benefit compared to PET/CT in patients with prostate cancer, and now needs to be further evaluated in prospective trials.     

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.     

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     

Treatment planning after hydrogel injection during radiotherapy of prostate cancer

Purpose

Imaging for treatment planning shortly after hydrogel injection is optimal for practical purposes, reducing the number of appointments. The aim was to evaluate the actual difference between early and late imaging.

Patients and methods

Treatment planning computed tomography (CT) was performed shortly after injection of 10 ml hydrogel (CT1) and 1–2 weeks later (CT2) for 3 patients. The hydrogel was injected via the transperineal approach after dissecting the space between the prostate and rectum with a saline/lidocaine solution of at least 20-ml. Hydrogel volume and distances between the prostate and rectal wall were compared. Intensity-modulated radiotherapy (IMRT) plans up to a dose of 78 Gy were generated (rectum V₇₀?<?20?%, rectum V₅₀?<?50?%; with the rectum including hydrogel volume for planning).

Results

A mean planning treatment volume of 104 cm³ resulted for a prostate volume of 37 cm³. Hydrogel volumes of 30 and 10 cm³ were determined in CT1 and CT2, respectively. Distances between the prostate and rectal wall at the levels of the base, middle, and apex were 1.7 cm, 1.6 cm, 1.5 cm in CT1 and 1.3 cm, 1.2 cm, 0.8 cm in CT2, respectively, corresponding to a mean decrease of 24, 25, and 47?%. A small overlap between the PTV and the rectum was found only in 1 patient in CT2 (0.2 cm³). The resulting mean rectum (without hydrogel) V₇₅, V₇₀, V₆₀, V₅₀ increased from 0?%, 0?%, 0.6?%, 10?% in CT1 to 0.1?%, 1.2?%, 6?%, 20?% in CT2, respectively.

Conclusion

Treatment planning based on imaging shortly after hydrogel injection overestimates the actual hydrogel volume during the treatment as a result of not-yet-absorbed saline solution and air bubbles.     

Upright Cone CT of the hindfoot: Comparison of the non-weight-bearing with the upright weight-bearing position

Objectives

To prospectively compare computed tomography (CT) of the hindfoot in the supine non-weight-bearing position (NWBCT) with upright weight-bearing position (WBCT).

Methods

Institutional review board approval and informed consent of all patients were obtained. NWBCT and WBCT scans of the ankle were obtained in 22 patients (mean age, 46.0?±?17.1 years; range 19–75 years) using a conventional 64-row CT for NWBCT and a novel cone-beam CT for WBCT. Two musculoskeletal radiologists independently performed the following measurements: the hindfoot alignment angle, fibulocalcaneal and tibiocalcaneal distances, lateral talocalcaneal joint space width, talocalcaneal overlap and naviculocalcaneal distance. Significant changes between NWBCT and WBCT were sought using Wilcoxon signed-rank test. P values <0.05 were considered statistically significant.

Results

Significant differences were found for all measurements except the hindfoot alignment angle and tibiocalcaneal distance. Significant measurement results were as follows (NWBCT/WBCT reader 1; NWBCT/WBCT reader 2, mean ± standard deviation): fibulocalcaneal distance 3.6 mm?±?5.2/0.3 mm?±?6.0 (P?=?0.006); 1.4 mm?±?6.3/-1.1 mm?±?6.3 (P?=?0.002), lateral talocalcaneal joint space width 2.9 mm?±?1.7/2.2 mm?±?1.1 (P?=?0.005); 3.4 mm?±?1.9/2.4 mm?±?1.3 (P?=?0.001), talocalcaneal overlap 4.1 mm?±?3.9/1.4 mm?±?3.9 (P?=?0.001); 4.5 mm?±?4.3/1.4 mm?±?3.7 (P?<?0.001) and naviculocalcaneal distance 13.5 mm?±?4.0/15.3 mm?±?4.7 (P?=?0.037); 14.0 mm?±?4.4/15.7 mm?±?6.2 (P?=?0.100). Interreader agreement was good to excellent (ICC 0.48–0.94).

Conclusion

Alignment of the hindfoot significantly changes in the upright weight-bearing CT position. Differences can be visualised and measured using WBCT.

Key Points

? Cone-beam computed tomography (CBCT) offers new opportunities for musculoskeletal problems ? Visualization and quantification of hindfoot alignment are possible in upright weight-bearing CBCT ? Hindfoot alignment changes significantly from non-weight-bearing to weight-bearing CT ? The weight-bearing position leads to a decrease in the fibulocalcaneal distance and talocalcaneal overlap ? The naviculocalcaneal distance is increased in the weight-bearing position     

Temporal evolution of administered activity in cardiac gated SPECT and patients’ effective dose: analysis of an historical series

Purpose

Myocardial perfusion imaging contributes >20 % of the average medical radiation exposure to the population in the USA. Imaging protocols able to achieve a radiation exposure ≤9 mSv in 50 % of the studies by 2014 have been recommended. The aim of this study was to analyse the temporal evolution of administered activities in patients scheduled for dual-day ^99mTc tracer gated single photon emission computed tomography (SPECT) and to compare different dose administration protocols in terms of patients’ effective dose.

Methods

Patients evaluated from 1 July 2002 to 31 January 2012 were allocated according to the protocol adopted: group 1: fixed activity according to diagnostic reference level: 740 MBq up to 80 kg (adapted for weight <60 kg); 900 MBq 80–100 kg, 1,110 MBq >100 kg, standard filtered back-projection (FBP) reconstruction; group 2: weight-adjusted activity: 8 MBq/kg up to 1,110 MBq, standard FBP reconstruction; and group 3: 4 MBq/kg, UltraSPECT wide beam reconstruction (WBR) reconstruction. A dual-head Anger camera (GE Helix) was used.

Results

A total of 9,060 patients were allocated to different groups: 4,751 in group 1, 2,844 in group 2 and 1,465 in group 3. The stress?+?rest administered activity was 1,617?±?180 in group 1, 1,136?±?260 in group 2 and 682?±?164 MBq in group 3 (all p?<?0.001). Patients’ effective dose was 13.7?±?3 in group 1, 9.5?±?2.8 in group 2 and 5.7?±?1.6 mSv in group 3 (all p?<?0.001). The 50th percentile was 12.6 in group 1, 9.1 in group 2 and 5.3 mSv in group 3. The effective dose received by the dedicated cardiologists was 2.1, 1.5 and 1.0 μSv/exam in group 1, group 2 and group 3 periods, respectively (all p?<?0.001).

Conclusion

A significant reduction over time in the administered activity for gated SPECT was achieved; accordingly, a significant reduction in patients’ exposure was obtained. A simple weight-adjusted strategy with 8 MBq/kg immediately fulfils the recommendations to limit exposure. In selected group 3 patients, a stress-only strategy allows for studies with <3 mSv exposure. Thus, at least the adoption of a new reconstruction algorithm is strongly encouraged, and suggested tracer activities for cardiac gated SPECT are to be revised.     

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.     

Respiratory gated PET/CT in a European multicentre retrospective study: added diagnostic value in detection and characterization of lung lesions

Purpose

The aim of our work is to evaluate the added diagnostic value of respiratory gated (4-D) positron emission tomography/computed tomography (PET/CT) in lung lesion detection/characterization in a large patient population of a multicentre retrospective study.

Methods

The data of 155 patients (89 men, 66 women, mean age 63.9?±?11.1?years) from 5 European centres and submitted to standard (3-D) and 4-D PET/CT were retrospectively analysed. Overall, 206 lung lesions were considered for the analysis (mean ± SD lesions dimension 14.7 ± 11.8?mm). Maximum standardized uptake values (SUV_max) and lesion detectability were assessed for both 3-D and 4-D PET/CT studies; 3-D and 4-D PET/CT findings were compared to clinical follow-up as standard reference.

Results

Mean ± SD 3-D and 4-D SUV_max values were 5.2 ± 5.1 and 6.8 ± 6.1 (p?Conclusion The respiratory gated PET/CT technique is a valuable clinical tool in diagnosing lung lesions, improving quantification and confidence in reporting, reducing 3-D undetermined findings and increasing the overall accuracy in lung lesion detection and characterization.     

Lung cancer perfusion: can we measure pulmonary and bronchial circulation simultaneously?

Objective

To describe a new CT perfusion technique for assessing the dual blood supply in lung cancer and present the initial results.

Methods

This study was approved by the institutional review board. A CT protocol was developed, and a dual-input CT perfusion (DI-CTP) analysis model was applied and evaluated regarding the blood flow fractions in lung tumours. The pulmonary trunk and the descending aorta were selected as the input arteries for the pulmonary circulation and the bronchial circulation respectively. Pulmonary flow (PF), bronchial flow (BF), and a perfusion index (PI, = PF/ (PF + BF)) were calculated using the maximum slope method. After written informed consent was obtained, 13 consecutive subjects with primary lung cancer underwent DI-CTP.

Results

Perfusion results are as follows: PF, 13.45?±?10.97?ml/min/100?ml; BF, 48.67?±?28.87?ml/min/100?ml; PI, 21?%?±?11?%. BF is significantly larger than PF, P?r?=?0.671, P?=?0.012).

Conclusion

The dual-input CT perfusion analysis method can be applied successfully to lung tumours. Initial results demonstrate a dual blood supply in primary lung cancer, in which the systemic circulation is dominant, and that the proportion of the two circulation systems is moderately dependent on tumour size.

Key Points

• A new CT perfusion technique can assess lung cancer's dual blood supply.
• A dual blood supply was confirmed with dominant bronchial circulation in lung cancer.
• The proportion of the two circulations is moderately dependent on tumour size.
• This new technique may benefit the management of lung cancer.

     

Initial experience of percutaneous transthoracic needle biopsy of lung nodules using C-arm cone-beam CT systems

Objective

To describe our initial experience with percutaneous transthoracic biopsy (PCNB) of lung nodules using C-arm cone-beam CT (CBCT).

Materials

Seventy-one consecutive patients with lung nodules of 30 mm or smaller underwent CBCT-guided PCNB using a coaxial cutting needle. We evaluated the procedure time, coaxial introducer dwell time, the numbers of pleural passages, coaxial introducer repositionings and CT acquisitions, as well as the technical success rate and radiation doses. Diagnostic accuracy, sensitivity, specificity and incidence of complications were also evaluated.

Results

PCNB was performed for 71 nodules: 63 solid, 6 part-solid and 2 ground-glass nodules. The procedure time, coaxial introducer dwell time, numbers of pleural passages, coaxial introducer repositionings and CT acquisitions were 17.9?±?5.9 min, 8.7?±?3.8 min, 1.1?±?0.4, 0.2?±?0.5 and 2.9?±?0.7, respectively. The technical success rate was 100% and the radiation dose was 272?±?116 mGy. Thirty-six nodules (50.7%) were diagnosed as malignant, 25 (35.2%) as benign and 10 (14.1%) as indeterminate. Diagnostic accuracy, sensitivity, specificity and incidence of complications were 98.4%, 97%, 100% and 38%, respectively. Complications included pneumothorax in 18 patients (25.4%), haemoptysis in 10 (14.1%) and chest pain in one (1.4%).

Conclusion

Under CBCT guidance, PCNB of lung nodules can be performed accurately, providing both real-time fluoroscopic guidance and CT imaging capabilities.     

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     

Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging

Purpose

The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard.

Methods

Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician.

Results

Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group ?0.2 ± 33.6 %, R ²?=?0.98, p?<?0.001; beta group 10.31 ± 69.86 %, R ²?=?0.97, p?<?0.001).

Conclusion

In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method.     

Optimal table feed in run-off CT angiography in patients with abdominal aortic aneurysms

Objectives

To assess the influence of different table feeds (TFs) on vascular enhancement and image quality in patients with an abdominal aortic aneurysm (AAA) undergoing computed tomography (CT) angiography of the lower extremities (run-off CTA).

Methods

Seventy-nine patients (71?±?8 years) with an AAA (>30 mm) who underwent run-off CTA between January 2004 and August 2011 were included in this retrospective institutional review board-approved study. Run-off CTA was conducted using 16- and 64-row CT. The range of TFs was 30–86 mm/s and was categorised in quartiles TF1 (32.6?±?1.9 mm/s), TF2 (38.9?±?0.9 mm/s), TF3 (43.9?±?3.1 mm/s) and TF4 (57.4?±?10.5 mm/s). Image quality was rated independently by two radiologists and vessel enhancement was assessed.

Results

Image quality was diagnostic at all aortic, pelvic and almost all thigh levels. Below the knee, the number of diagnostic levels was highest for TF1 and decreased to TF4. Arterial enhancement between the aorta and fibular trunk was not different in all TF groups, P?>?0.05. At the calf and foot strongest arterial enhancement was noted for TF1 and TF2 and decreased to TF4, P?<?0.01.

Conclusion

Results indicate that the highest image quality of run-off CTA in patients with an AAA may be obtained using table feeds measuring 30–35 mm/s.

Key Points

? CTA has become a key investigation for peripheral vascular disease. ? Run-off CTA is more complex in patients with an abdominal aortic aneurysm. ? Run-off CTA is feasible with a short bolus of intravenous contrast medium. ? A constant 30–35 mm/s table feed provides the highest likelihood of diagnostic images.     

Comparison of abdominal MRI with diffusion-weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas

Purpose

The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and ⁶⁸Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas.

Methods

Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w?+?DW MRI, T2w?+?contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar’s test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student’s t test.

Results

Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23?=?61 %; observer 2: 15/23?=?65.2 %; p?<?0.05) or CE T1w images (observer 1: 14/23?=?61 %; observer 2: 15/23?=?65.2 %; p?<?0.05). Detection rates of pancreatic NET with PET/CT (both observers: 23/23?=?100 %) were statistically significantly higher than with MRI (p?<?0.05). The mean ADC value of NET (1.02?±?0.26?×?10^?3?mm²/s) was statistically significantly lower than that of normal pancreatic tissue (1.48?±?0.39?×?10^?3?mm²/s).

Conclusion

DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. ⁶⁸Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET.     

Tangential vs. defined radiotherapy in early breast cancer treatment without axillary lymph node dissection

Purpose

Recent studies have demonstrated low regional recurrence rates in early-stage breast cancer omitting axillary lymph node dissection (ALND) in patients who have positive nodes in sentinel lymph node dissection (SLND). This finding has triggered an active discussion about the effect of radiotherapy within this approach. The purpose of this study was to analyze the dose distribution in the axilla in standard tangential radiotherapy (SRT) for breast cancer and the effects on normal tissue exposure when anatomic level I–III axillary lymph node areas are included in the tangential radiotherapy field configuration.

Patients and methods

We prospectively analyzed the dosimetric treatment plans from 51 consecutive women with early-stage breast cancer undergoing radiotherapy. We compared and analyzed the SRT and the defined radiotherapy (DRT) methods for each patient. The clinical target volume (CTV) of SRT included the breast tissue without specific contouring of lymph node areas, whereas the CTV of DRT included the level I–III lymph node areas.

Results

We evaluated the dose given in SRT covering the axillary lymph node areas of level I–III as contoured in DRT. The mean V_D95?% of the entire level I–III lymph node area in SRT was 50.28?% (range, 37.31–63.24?%), V_D45 Gy was 70.1?% (54.8–85.4?%), and V_D40 Gy was 83.5?% (72.3–94.8?%). A significant difference was observed between lung dose and heart toxicity in SRT vs. DRT. The V_20 Gy and V_30 Gy of the right and the left lung in DRT were significantly higher in DRT than in SRT (p?<?0.001). The mean heart dose in SRT was significantly lower (3.93 vs. 4.72 Gy, p?=?0.005).

Conclusion

We demonstrated a relevant dose exposure of the axilla in SRT that should substantially reduce local recurrences. Furthermore, we demonstrated a significant increase in lung and heart exposure when including the axillary lymph nodes regions in the tangential radiotherapy field set-up.     

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.     

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.     

Evaluation of early response to concomitant chemoradiotherapy by interim 18F-FDG PET/CT imaging in patients with locally advanced oesophageal carcinomas

Purpose

The best way to assess the response to chemoradiotherapy of locally advanced oesophageal carcinomas is not known. We used ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT to evaluate the metabolic response during chemoradiotherapy and tried to correlate this response to survival.

Methods

Patients with biopsy-proven oesophageal carcinoma underwent FDG PET/CT with evaluation of the standardized uptake value (SUV) before any treatment (SUV1) and during chemoradiotherapy after two cycles of 5-fluorouracil (FU)/cisplatin and 20 Gy (SUV2). Metabolic response was defined as 1?(SUV2/SUV1). Surgery was discussed after 40 Gy and three cycles of chemotherapy. Results of interim PET were not considered for the therapeutic decision.

Results

Among 72 patients who underwent a first FDG PET/CT before any treatment, 59 (82 %) could receive the second FDG PET/CT examination. Median survival was 22.2 months with 1-year and 2-year survivals of 70 and 46 %, respectively. Nineteen patients (32 %) underwent surgery. Mean SUV1 and SUV2 were 12.3?±?6.2 and 6?±?4.1, respectively (p?<?0.001). Using a cut-off for metabolic response of 50 %, sensitivity and specificity for survival were 0.7 and 0.58. The 2-year overall survival of good responders was 62 % as compared to 27 % for poor metabolic responders. A multivariate analysis was performed, including T and N stages, surgery, histology and metabolic response: only metabolic response was significantly (p?=?0.009) associated with 2-year survival.

Conclusion

Early evaluation of metabolic response had a great prognostic value and could help identify good responders to chemoradiotherapy.     

Image quality of ultra-low radiation exposure coronary CT angiography with an effective dose <0.1 mSv using high-pitch spiral acquisition and raw data-based iterative reconstruction

Objectives

We evaluated the potential of prospectively ECG-triggered high-pitch spiral acquisition with low tube voltage and current in combination with iterative reconstruction to achieve coronary CT angiography with sufficient image quality at an effective dose below 0.1 mSv.

Methods

Contrast-enhanced coronary dual source CT angiography (2?×?128?×?0.6 mm, 80 kV, 50 mAs) in prospectively ECG-triggered high-pitch spiral acquisition mode was performed in 21 consecutive individuals (body weight <100 kg, heart rate ≤60/min). Images were reconstructed with raw data-based filtered back projection (FBP) and iterative reconstruction (IR). Image quality was assessed on a 4-point scale (1 = no artefacts, 4 = unevaluable).

Results

Mean effective dose was 0.06?±?0.01 mSv. Image noise was significantly reduced in IR (128.9?±?46.6 vs. 158.2?±?44.7 HU). The mean image quality score was lower for IR (1.9?±?1.1 vs. 2.2?±?1.0, P?<?0.0001). Of 292 coronary segments, 55 in FBP and 40 in IR (P?=?0.12) were graded “unevaluable”. In patients with a body weight ≤75 kg, both in FBP and in IR, the rates of fully evaluable segments were significantly higher in comparison to patients >75 kg.

Conclusions

Coronary CT angiography with an estimated effective dose <0.1 mSv may provide sufficient image quality in selected patients through the combination of high-pitch spiral acquisition and raw data-based iterative reconstruction.

Key Points

? Coronary CT angiography with an estimated effective dose <0.1 mSv is possible. ? Combination of high-pitch spiral acquisition with iterative reconstruction achieves sufficient image quality. ? Diagnostic accuracy remains to be assessed in future trials.