Long-Term Changes in Aortic Length after Thoracic Endovascular Aortic Repair.

PURPOSE: To study long-term changes to the thoracic aorta following thoracic endovascular aortic repair (TEVAR) for treatment of different aortic pathologic conditions. MATERIALS AND METHODS: This retrospective study included 53 consecutive patients (mean age, 58.8 y ± 14; 13 female and 40 male) in whom TEVAR was performed between October 2002 and May 2010. The mean duration of follow-up was 21.1 months (range, 0.5-96 mo). Statistical analysis was performed with the Friedman test and Conover-Iman test. RESULTS: Nineteen patients with aortic aneurysm (group 1), 25 patients with type B dissection (group 2), and 9 patients with other pathologic conditions (group 3) were treated with TEVAR. The mean overall aortic lengths (from the origin of the left subclavian artery to the origin of the celiac trunk) before TEVAR were 271.4 mm, 268.6 mm, and 233.6 mm in groups 1, 2, and 3, respectively. At 12-month follow-up, the lengths were 282.8 mm, 294.4 mm, and 237.5 mm in groups 1, 2, and 3, respectively. The changes in aortic lengths following TEVAR were statistically significant (P < .001). A second intervention was required in 14 patients, and 6 patients died during follow-up. CONCLUSIONS: A significant change in the overall aortic length was observed following TEVAR. The changes in aortic length reached statistical significance after 12 months.

Iterative Reconstruction Leads to Increased Subjective and Objective Image Quality in Cranial CT in Patients With Stroke.

OBJECTIVE: The purpose of this study was to determine whether iterative reconstruction improves the quality of cranial CT (CCT) images of stroke patients. MATERIALS AND METHODS: Fifty-one CCT studies of patients with infarction performed with either a low (260 mAs; n = 21) or standard (340 mAs; n = 30) dose were reconstructed with both filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with five strength levels (S1-S5). The resulting six image sets (one FBP and one each for SAFIRE levels S1-S5) were rated separately by two blinded radiologists in terms of conspicuity of infarcted areas on a 5-point scale. Noise and infarct-to-normal brain as well as medullary-to-cortical contrast-to-noise ratios (CNRs) were measured. Ratings, noise, and CNRs were intraindividually compared within the same dose group (Fisher exact test) and interindividually between the different dose groups (Wilcoxon-Mann-Whitney U test). RESULTS: The strength level S4 showed the best conspicuity of infarcted areas. Compared with FBP, SAFIRE S4 statistically significantly (p < 0.01) reduced noise and improved CNRs without statistically significant differences in all subjective and objective criteria (p > 0.01) when the dose was reduced. Patients examined with a 260-mAs low-dose were exposed to a statistically significantly lower dose (1.77 vs 2.33 mSv; p < 0.01). CONCLUSION: Iterative reconstruction (SAFIRE at strength level S4) leads to increased subjective and objective image quality in CCT and allows dose reduction (-24%) without losses in the demarcation of ischemic lesions.

Automated Tube Potential Selection as a Method of Dose Reduction for CT of the Neck: First Clinical Results.

OBJECTIVE: The objective of our study was to investigate whether the use of a software-based automated tube potential selection (ATPS) CT neck protocol can result in radiation dose reduction as compared with a set 120-kV protocol without a statistically significant reduction in image quality. MATERIALS AND METHODS: Three hundred sixty-four patients (median age, 52 years) underwent CT of the neck. Group 1 (n = 320) underwent CT with ATPS with 80, 100, or 120 kV. Group 2 (n = 44) was examined with the standard CT protocol at 120 kV. Attenuation, image background noise, signal-to-noise ratio (SNR), dose-length product (DLP), volume CT dose index (CTDIvol), body mass index (BMI [weight in kilograms divided by the square of height in meters]), and subjective image quality (5-point Likert scale, two readers in consensus) were analyzed. RESULTS: A tube potential of 100 kV was selected in 279 patients, 120 kV in 40 patients, and 80 kV in one patient of the ATPS group. A significant correlation was found for selected tube potential and BMI (80 kV, BMI = 20.4; 100 kV, mean BMI = 24.2; 120 kV, BMI = 28.6; r = 0.28, p < 0.01). The average radiation dose was significantly lower with ATPS activated than with the standard protocol (mean DLP, 259 vs 350 mGy × cm, respectively). Background noise did not differ between groups 1 and 2 at the levels of the mandibular angle and the upper mediastinum; however, attenuation and SNR increased significantly with lower tube potential settings. Subjective image quality did not suffer (mean image quality score: ATPS protocol vs standard protocol, 4.56 vs 4.61, respectively; p > 0.05) with good interobserver agreement (κ > 0.56). CONCLUSION: ATPS allows significant dose savings for CT of the neck compared with a standard protocol that uses a fixed 120-kV setting without a statistically significant reduction in image quality.

Objective and subjective image quality of primary and recurrent squamous cell carcinoma on head and neck low-tube-voltage 80-kVp computed tomography.

INTRODUCTION: To investigate low-tube-voltage 80-kVp computed tomography (CT) of head and neck primary and recurrent squamous cell carcinoma (SCC) regarding objective and subjective image quality. METHODS: We retrospectively evaluated 65 patients (47 male, 18 female; mean age: 62.1 years) who underwent head and neck dual-energy CT (DECT) due to biopsy-proven primary (n = 50) or recurrent (n = 15) SCC. Eighty peak kilovoltage and standard blended 120-kVp images were compared. Attenuation and noise of malignancy and various soft tissue structures were measured. Tumor signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was rated by three reviewers using 5-point grading scales regarding overall image quality, lesion delineation, image sharpness, and image noise. Radiation dose was assessed as CT dose index volume (CTDIvol). Interobserver agreement was calculated using intraclass correlation coefficient (ICC). RESULTS: Mean tumor attenuation (153.8 Hounsfield unit (HU) vs. 97.1 HU), SNR (10.7 vs. 8.3), CNR (8.1 vs. 4.8), and subjective tumor delineation (score, 4.46 vs. 4.13) were significantly increased (all P < 0.001) with 80-kVp acquisition compared to standard blended 120-kVp images. Noise of all measured structures was increased in 80-kVp acquisition (P < 0.001). Overall interobserver agreement was good (ICC, 0.86; 95 % confidence intervals: 0.82-0.89). CTDIvol was reduced by 48.7 % with 80-kVp acquisition compared to standard DECT (4.85 ± 0.51 vs. 9.94 ± 0.81 mGy cm, P < 0.001). CONCLUSIONS: Head and neck CT with low-tube-voltage 80-kVp acquisition provides increased tumor delineation, SNR, and CNR for CT imaging of primary and recurrent SCC compared to standard 120-kVp acquisition with an accompanying significant reduction of radiation exposure.

Transarterial chemoembolization of unresectable systemic chemotherapy-refractory liver metastases from colorectal cancer: long-term results over a 10-year period.

The aims of the study were to evaluate therapeutic efficacy and to determine the prognostic factors for treatment success in patients with liver metastases from colorectal cancer (CRC) treated with transarterial chemoembolization (TACE). A total of 564 patients (mean age, 60.3 years) with liver metastases of CRC were repeatedly treated with TACE. In total, 3,384 TACE procedures were performed (mean, six sessions per patient). The local chemotherapy protocol consisted of mitomycin C alone (43.1%), mitomycin C with gemcitabine (27.1%), mitomycin C with irinotecan (15.6%) or mitomycin C with irinotecan and cisplatin (15.6%). Embolization was performed with lipiodol and starch microspheres. Tumor response was evaluated using magnetic resonance imaging or computed tomography. The change in tumor size was calculated and the response was evaluated according to the RECIST-Criteria. Survival rates were calculated according to the Kaplan-Meier method. Prognostic factors for patient's survival were evaluated using log-rank test. Evaluation of local tumor control showed partial response in 16.7%, stable disease in 48.2% and progressive disease in 16.7%. The 1-year survival rate after chemoembolization was 62%, the 2-year survival rate was 28% and the 3-year survival rate was 7%. Median survival from the start of chemoembolization treatment was 14.3 months. The indication (p = 0.001) and initial tumor response (p = 0.015) were statistically significant factors for patient's survival. TACE is a minimally invasive therapy option for controlling local metastases and improving survival time in patients with hepatic metastases from CRC. TN stage, extrahepatic metastases, number of lesions, tumor location within the liver and choice of chemotherapy protocol of TACE are none significant factors for patient's survival.

Whole-body MR angiography: first experiences with the new TimCT technology with single contrast injection.

PURPOSE: To assess image quality, presence of artifacts, arterial stenosis, and interobserver agreement of Tim-CT in assessment of the arterial system using contrast-enhanced whole-body-MRA (CE-Wb-MRA) with a single contrast-medium injection in patients with arteriosclerosis. MATERIALS AND METHODS: The retrospective study included 18 patients (mean age, 68 years). A total of 468 arteries were evaluated. CE-Wb-MRA was performed using Tim-CT technology on a 1.5 Tesla (T) MRI after injecting a single dose of Vasovist. Evaluations were independently performed by two radiologists. The arterial system was divided into seven anatomic locations. Each radiologist assessed the image quality, degree of artifacts, and arterial stenosis in different locations. RESULTS: All Wb-MRA examinations were technically successful. Image quality: 28.42% arteries were excellent, 29.17% were good, 22.54% were satisfactory, 9.40% were poor, and 5.13% of insufficient quality. Occurrence of artifacts: 37.25% were free of artifacts, 49.44% minimal artifacts not affecting diagnosis, and 13.31% strong artifacts not permitting a diagnosis. A total of 60.00% arteries showed no stenosis, 8.76% were ≤50% stenotic, 5.17% were 51-75% stenotic, 4.38% were 76-99%, and 8.54% total occlusion. The interobserver agreement was good for supra-aortic, pelvic, and upper and lower leg regions. CONCLUSION: CE-Wb-MRA using the TimCT technology and with a single contrast injection is a feasible tool for whole-body MRA.

Topogram-based automated selection of the tube potential and current in thoraco-abdominal trauma CT - a comparison to fixed kV with mAs modulation alone.

OBJECTIVE: To investigate the impact of automated attenuation-based tube potential selection on image quality and exposure parameters in polytrauma patients undergoing contrast-enhanced thoraco-abdominal CT. METHODS: One hundred patients were examined on a 16-slice device at 120 kV with 190 ref.mAs and automated mA modulation only. Another 100 patients underwent 128-slice CT with automated mA modulation and topogram-based automated tube potential selection (autokV) at 100, 120 or 140 kV. Volume CT dose index (CTDI(vol)), dose-length product (DLP), body diameters, noise, signal-to-noise ratio (SNR) and subjective image quality were compared. RESULTS: In the autokV group, 100 kV was automatically selected in 82 patients, 120 kV in 12 patients and 140 kV in 6 patients. Patient diameters increased with higher kV settings. The median CTDI(vol) (8.3 vs. 12.4 mGy; -33%) and DLP (594 vs. 909 mGy cm; -35%) in the entire autokV group were significantly lower than in the group with fixed 120 kV (p < 0.05 for both). Image quality remained at a constantly high level at any selected kV level. CONCLUSION: Topogram-based automated selection of the tube potential allows for significant dose savings in thoraco-abdominal trauma CT while image quality remains at a constantly high level. KEY POINTS: • Automated kV selection in thoraco-abdominal trauma CT results in significant dose savings • Most patients benefit from a 100-kV protocol with relevant DLP reduction • Constantly good image quality is ensured • Image quality benefits from higher kV when arms are positioned downward.

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 < 0.05) but no significant differences between single- and dual-contrast-phase series (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.

MR-guided laser-induced thermotherapy in ex vivo porcine kidney: comparison of four different imaging sequences.

PURPOSE: To evaluate the clinical value of different magnetic resonance imaging (MRI) sequences for a real-time thermo-monitoring during laser-induced thermotherapy (LITT) in kidneys. METHODS: Twenty-eight ex vivo pig kidneys were treated with laser ablation under MR guidance in a high-field MR scanner (Magnetom Espree or Avanto Fit, Siemens, Germany). For the thermal ablation of the kidney, a neodymium yttrium-aluminum-garnet (Nd:YAG) laser was used in combination with a special protective catheter (length 43 cm, 4 French) which is sealed at the distal end. First, ablation was performed for 7, 10, and 13 minutes using FLASH sequences for investigation of time-dependent growth of lesion size. In the second step, we evaluated the optimal imaging sequence during a 7 minutes ablation of the kidney and after cooling using four different MR sequences (Haste, FLASH, radial VIBE, and Caipirinha DIXON). RESULTS: Macroscopic lesion volume increased from 3,784 ± 1,525 mm(3) to 7,683 ± 5,756 mm(3) after the ablation from 7 to 13 minutes and MR volume ranged from 2,107 ± 1,674 mm(3) to 2,934 ± 1,549 mm(3) after the ablation from 7 to 13 minutes. During ablation, FLASH (132 ± 34%) and radial VIBE (120 ± 43%) sequences displayed lesion volumes most efficiently with a trend to overestimation. The Caipirinha DIXON (323 ± 24%) sequence overestimated the volumes significantly during real-time monitoring. The volumes measured by MRI with FLASH (61 ± 30%), Haste (67 ± 28%), or radial VIBE (48 ± 14%) sequences after cooling of the kidney after ablation were always underestimated. The Caipirinha DIXON (142 ± 2%) sequence still overestimated the lesion volume after cooling of the kidney. CONCLUSION: LITT is a feasible ablation modality in kidney tissue. Moreover, macroscopic and MR lesion volume increases time-dependently. For online monitoring, radial VIBE and FLASH sequences seem to be most efficient.

70 kV computed tomography of the thorax: valence for computer-assisted nodule evaluation and radiation dose - first clinical results.

BACKGROUND: Computed tomography (CT) is the gold standard for evaluation of pulmonary nodules and is at the same time responsible for the majority of the collective effective dose. PURPOSE: To evaluate radiation dose and efficacy of computer-assisted detection (CAD) for solid pulmonary nodules in low dose chest CT performed at 70 kV. MATERIAL AND METHODS: CAD was performed upon chest CT with 70 kV and 100 kV (gold standard) at manufacture's recommended tube current of 87 mAs (collimation, 64 × 0.6 mm). Detection rate for pulmonary nodules and size measurements of both techniques were compared to each other. Radiation dosage in terms of effective dose (E) was measured using an Alderson-Rando Phantom. RESULTS: Seventy-four patients with 301 solid nodules were included in the study. CAD detection rate was similar for 70 kV (94.7%) and 100 kV (92.4%). Mean transversal nodule diameter was 5.5 mm for 70 kV and 5.7 mm for 100 kV with an average volume of 0.12 mL (both techniques). Derived from the phantom measurements patient examinations resulted in an E of 0.51 mSv (70 kV) versus 2.02 mSv (100 kV). CONCLUSION: 70 kV low-dose chest CT is suitable for CAD based lung nodule analysis at a fraction of the radiation burden of the standard technique. Since the measurements are highly accurate, 70 kV CT could be used for detection of pulmonal lesions as well as follow-up studies.

Analysis of laryngeal fractures in decomposed bodies using microfocus computed tomography (mfCT).

Postmortem computed tomography (CT) is now routinely performed in forensic autopsies. Microfocus computed tomography (mfCT) has attracted recent attention because it can provide more detailed information than routine postmortem CT can. This feasibility study evaluated the usefulness of mfCT for examination of the hyoid bone and thyroid cartilage in cases of suspected strangulation, where advanced decomposition precludes detection of petechial hemorrhages and hemorrhages adjacent to fractures. The results show that mfCT was useful for identification of thin fracture lines in the fragile laryngeal structures. We suggest that mfCT should be considered for forensic autopsies in cases of suspected strangulation with advanced decomposition.

Accuracy and speed of robotic assisted needle interventions using a modern cone beam computed tomography intervention suite: a phantom study.

OBJECTIVE: To analyse the feasibility and accuracy of robotic aided interventions on a phantom when using a modern C-arm-mounted cone beam computed tomography (CBCT) device in combination with needle guidance software. METHODS: A small robotic device capable of holding and guiding needles was attached to the intervention table. After acquiring a 3D data set the access path was planned on the CBCT workstation and shown on the intervention monitor. Then the robot was aligned to the live fluorosopic image. A total of 40 punctures were randomly conducted on a phantom armed with several targets (diameter 2 mm) in single and double oblique trajectory (n = 20 each). Target distance, needle deviation and time for the procedures were analysed. RESULTS: All phantom interventions (n = 40) could be performed successfully. Mean target access path within the phantom was 8.5 cm (min 4.2 cm, max 13.5 cm). Average needle tip deviation was 1.1 mm (min 0 mm, max 4.5 mm), time duration was 3:59 min (min 2:07 min, max 10:37 min). CONCLUSION: When using the proposed robot device in a CBCT intervention suite, highly accurate needle-based interventional punctures are possible in a reasonable timely manner in single as well as in double oblique trajectories.

Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality.

OBJECTIVE: The purpose of this study was to evaluate the efficiency of automatic bone removal in dual-energy CT angiography (CTA) of the trunk. SUBJECTS AND METHODS: Nineteen patients underwent dual-energy CTA of the trunk (tube A, 140 kV; tube B, 100 kV). In addition to the dual-energy dataset, an image equivalent to that of a standard 120-kV single-energy examination was generated with both tubes. Automated bone segmentation was performed on both datasets, and the results were analyzed. The time required for and subjective image quality of the maximum intensity projections (MIPs) generated were evaluated. RESULTS: Errors in bone segmentation were found for 1.5% of bones on dual-energy images and 12.4% of bones on single-energy images (p < 0.01). The most important differences were found in the rib cage, sternum, and pelvis. The times required for postprocessing of MIPs were similar for the dual-energy (113.5 seconds) and single-energy (106.8 seconds) techniques. The subjective image quality of the arteries was considered better for dual-energy CTA (4.5 points) than for single-energy CTA (4.1 points) owing to false cutoff of vessels during the bone removal process on the single-energy images (p = 0.026). CONCLUSION: For CTA of the trunk, the dual-energy postprocessing capabilities for 3D visualization are superior to the threshold-based bone removal of single-energy CT. Dual-energy CTA can generate boneless MIP images of substantial quality.

Dual-energy CT applications in head and neck imaging.

OBJECTIVE: Dual-energy scanning is a breakthrough in CT technology that has several applications in chest and abdominal imaging. Dual-energy CT also has potential for head and neck imaging. This review describes the role of dual-energy CT in head and neck imaging. CONCLUSION: As with other body regions, both image fusion and material characterization dual-energy applications can be used for head and neck imaging. Early results are promising, and further research is encouraged.

Ultra-low dose dual-source high-pitch computed tomography of the paranasal sinus: diagnostic sensitivity and radiation dose.

BACKGROUND: Today's gold standard for diagnostic imaging of inflammatory diseases of the paranasal sinus is computed tomography (CT). PURPOSE: To evaluate diagnostic sensitivity and radiation dose of an ultra-low dose dual-source CT technique. MATERIAL AND METHODS: Paranasal sinuses of 14 cadaveric heads were independently evaluated by two readers using a modern dual-source CT with lowest reasonable dosage in high-pitch mode (100 kV, 10 mAs, collimation 0.6 mm, pitch value 3.0). Additionally the head part of an anthropomorphic Alderson-Rando phantom was equipped with thermoluminiscent detectors to measure radiation exposure to the eye lenses and thyroid gland. RESULTS: Diagnostic accuracy regarding sinusoidal fluid, nasal septum deviation, and mucosal swelling was 100%. Mastoid fluid was detected in 76% and 92%, respectively. In the phantom study, average measured eye lens dosage was 0.64 mGy; radiation exposure of the thyroid gland was 0.085 mGy. CONCLUSION: Regarding evaluation of inflammatory diseases of the paranasal sinus this study indicates sufficient accuracy of the proposed CT protocol at a very low dosage level.

Low-dose abdominal computed tomography for detection of urinary stone disease - Impact of additional spectral shaping of the X-ray beam on image quality and dose parameters.

OBJECTIVES: To evaluate a novel tin filter-based abdominal CT protocol for urolithiasis in terms of image quality and CT dose parameters. METHODS: 130 consecutive patients with suspected urolithiasis underwent non-enhanced CT with three different protocols: 48 patients (group 1) were examined at tin-filtered 150kV (150kV Sn) on a third-generation dual-source-CT, 33 patients were examined with automated kV-selection (110-140kV) based on the scout view on the same CT-device (group 2), and 49 patients were examined on a second-generation dual-source-CT (group 3) with automated kV-selection (100-140kV). Automated exposure control was active in all groups. Image quality was subjectively evaluated on a 5-point-likert-scale by two radiologists and interobserver agreement as well as signal-to-noise-ratio (SNR) was calculated. Dose-length-product (DLP) and volume CT dose index (CTDIvol) were compared. RESULTS: Image quality was rated in favour for the tin filter protocol with excellent interobserver agreement (ICC=0.86-0.91) and the difference reached statistical significance (p<0.001). SNR was significantly higher in group 1 and 2 compared to second-generation DSCT (p<0.001). On third-generation dual-source CT, there was no significant difference in SNR between the 150kV Sn and the automated kV selection protocol (p=0.5). The DLP of group 1 was 23% and 21% (p<0.002) lower in comparison to group 2 and 3, respectively. So was the CTDIvol of group 1 compared to group 2 (-36%) and 3 (-32%) (p<0.001). CONCLUSION: Additional shaping of a 150kV source spectrum by a tin filter substantially lowers patient exposure while improving image quality on un-enhanced abdominal computed tomography for urinary stone disease.

Impact of an endorectal coil for 1H-magnetic resonance spectroscopy of the prostate at 3.0T in comparison to 1.5T: Do we need an endorectal coil?

OBJECTIVES: To evaluate the influence of endorectal coil (ERC) regarding spectral quality and diagnostic suitability and diagnostic performance in 3.0T 1H-magnetic resonance spectroscopy imaging (MRSI) compared to 1.5T MRSI. MATERIALS AND METHODS: The study was approved by the Institutional Review Board. MRSI of the prostate was performed on 19 patients at 1.5T with ERC (protocol 1), at 3.0T with a disabled ERC (protocol 2) and at 3.0T with ERC (protocol 3). Age, weight, body size, body-mass-index, prostate volume, time between measurements, diagnostic suitability of spectra, histopathological results after biopsy of cancer suspect lesions (CSL), sensitivity and specificity were evaluated. Signal-to-noise ratio (SNR) was calculated and compared using semiparametrical multiple Conover-comparisons. Correlations between SNR and prostate volume and BMI were indicated using Pearson correlation coefficient. Distribution of SNR was evaluated for prostate quadrants. RESULTS: Diagnostic suitable spectra were achieved in 76 % (protocol 1, 100% in CSL), 32 % (protocol 2, 59% in CSL) and 50 % (protocol 3, 80% in CSL) of the voxels. SNR was significantly higher in protocol 3 compared to protocol 2 and 1 (93,729 vs. 27,836 vs. 32,897, p<0.0001) with significant difference between protocol 2 and 1 (p<0.023). Highest SNR was achieved in the dorsal prostate (protocols 1 and 3; p<0.0001). Sensitivity at 3.0T was higher with use of ERC. Specificity was highest at 1.5T with ERC. CONCLUSION: The ERC improves the diagnostic suitability and the SNR in MRSI at 3.0T. Less voxels at 3.0T with disabled ERC are suitable for diagnosis compared to 1.5T with ERC. MRSI at 3.0T with ERC shows the highest SNR. SNR in dorsal quadrants of the prostate was higher using ERC.

Intervention Planning Using a Laser Navigation System for CT-Guided Interventions: A Phantom and Patient Study.

OBJECTIVE: To investigate the accuracy, efficiency and radiation dose of a novel laser navigation system (LNS) compared to those of free-handed punctures on computed tomography (CT). MATERIALS AND METHODS: Sixty punctures were performed using a phantom body to compare accuracy, timely effort, and radiation dose of the conventional free-handed procedure to those of the LNS-guided method. An additional 20 LNS-guided interventions were performed on another phantom to confirm accuracy. Ten patients subsequently underwent LNS-guided punctures. RESULTS: The phantom 1-LNS group showed a target point accuracy of 4.0 ± 2.7 mm (freehand, 6.3 ± 3.6 mm; p = 0.008), entrance point accuracy of 0.8 ± 0.6 mm (freehand, 6.1 ± 4.7 mm), needle angulation accuracy of 1.3 ± 0.9° (freehand, 3.4 ± 3.1°; p < 0.001), intervention time of 7.03 ± 5.18 minutes (freehand, 8.38 ± 4.09 minutes; p = 0.006), and 4.2 ± 3.6 CT images (freehand, 7.9 ± 5.1; p < 0.001). These results show significant improvement in 60 punctures compared to freehand. The phantom 2-LNS group showed a target point accuracy of 3.6 ± 2.5 mm, entrance point accuracy of 1.4 ± 2.0 mm, needle angulation accuracy of 1.0 ± 1.2°, intervention time of 1.44 ± 0.22 minutes, and 3.4 ± 1.7 CT images. The LNS group achieved target point accuracy of 5.0 ± 1.2 mm, entrance point accuracy of 2.0 ± 1.5 mm, needle angulation accuracy of 1.5 ± 0.3°, intervention time of 12.08 ± 3.07 minutes, and used 5.7 ± 1.6 CT-images for the first experience with patients. CONCLUSION: Laser navigation system improved accuracy, duration of intervention, and radiation dose of CT-guided interventions.

Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions.

OBJECTIVE: To report our experience using C-arm cone beam CT (C-arm CBCT) combined with the new remote operated positioning and guidance system, iSYS1, for needle guidance during spinal interventions. METHODS: A C-arm CBCT with a flat panel angiography system was acquired (Artis Zeego; Siemens Healthcare Sector, Forchheim, Germany). Reconstruction of CT-like images and planning of the needle path were performed using a common workstation. The needle holder of iSYS1 acted as a guide during insertion of Kirschner (K) wires. 20 percutaneous K wires were placed in the pedicles at T2-T3, T7-T12, and L1-L2 in a cadaver specimen. Postprocedure C-arm CBCT scans were obtained to confirm the accuracy of the K wire placement. RESULTS: All K wire placements were successfully performed. Mean planning time with Syngo iGuide was 4:16 min, mean positioning time of iSYS1 was 3:35 min, and mean placement time of the K wires was 2:22 min. Mean total intervention time was 10:13 min per pedicle. A mean deviation of 0.35 mm between the planned path and the placed K wire with a mean path length of 6.73 cm was documented. CONCLUSIONS: Our results demonstrate the potential of combining C-arm CBCT with iSYS1 for safe and accurate percutaneous placement of pedicle K wires in spinal interventions.

70 kVp computed tomography pulmonary angiography: potential for reduction of iodine load and radiation dose.

PURPOSE: The purpose of the study was to evaluate 70 kVp dual-source computed tomography pulmonary angiography (CTPA) with reduced iodine load in comparison with single-source 70 and 100 kVp CTPA with standard iodine load regarding image quality and radiation dose. MATERIALS AND METHODS: Three groups with 40 consecutive patients each underwent either standard single-source 100 kVp (120 mAs; group A), single-source 70 kVp (208 mAs; group B), or dual-source 70 kVp CTPA (416 mAs; group C). A volume of 70 mL of contrast material with 400 mg I/mL (groups A, B) or 300 mg I/mL (group C) was administered. Chest diameter, dose-length product, intravascular signal attenuation, image noise, signal to noise ratio (SNR), and contrast to noise ratio (CNR) were compared. Two observers rated subjective image quality regarding intravascular enhancement and image noise using 5-point scales. RESULTS: Chest diameter and age were similar (P ≥ 0.28) for all groups. Compared with group A, the average dose-length product was 59% lower in group B (67.3 ± 11.8 vs. 164.7 ± 50.6 mGy cm, P<0.001) and similar between groups A and C (167.7 ± 41.2 mGy cm, P = 0.39). Average SNR and CNR were significantly higher for group C (21.5 ± 4.7 and 19.0 ± 4.5, respectively) compared with groups A (18.3 ± 3.5 and 15.8 ± 3.4, respectively) and B (17.3 ± 5.8 and 15.6 ± 5.5, respectively; all Ps ≤ 0.001). Subjective image quality ratings regarding enhancement and noise were highest for group C (1.73 ± 0.62 and 2.03 ± 0.66, respectively). CONCLUSIONS: Compared with standard 100 kVp CTPA, single-source 70 kVp CTPA allows for significant radiation dose savings with comparable SNR and CNR, whereas dual-source 70 kVp CTPA results in a superior objective image quality albeit a reduction of iodine concentration.