Carsten Schwenke

Computed tomography for preoperative planning in minimal-invasive total hip arthroplasty: radiation exposure and cost analysis.

Computed tomography (CT) was used for preoperative planning of minimal-invasive total hip arthroplasty (THA). 92 patients (50 males, 42 females, mean age 59.5 years) with a mean body-mass-index (BMI) of 26.5 kg/m(2) underwent 64-slice CT to depict the pelvis, the knee and the ankle in three independent acquisitions using combined x-, y-, and z-axis tube current modulation. Arthroplasty planning was performed using 3D-Hip Plan(®) (Symbios, Switzerland) and patient radiation dose exposure was determined. The effects of BMI, gender, and contralateral THA on the effective dose were evaluated by an analysis-of-variance. A process-cost-analysis from the hospital perspective was done. All CT examinations were of sufficient image quality for 3D-THA planning. A mean effective dose of 4.0 mSv (SD 0.9 mSv) modeled by the BMI (p<0.0001) was calculated. The presence of a contralateral THA (9/92 patients; p=0.15) and the difference between males and females were not significant (p=0.08). Personnel involved were the radiologist (4 min), the surgeon (16 min), the radiographer (12 min), and administrative personnel (4 min). A CT operation time of 11 min and direct per-patient costs of 52.80 € were recorded. Preoperative CT for THA was associated with a slight and justifiable increase of radiation exposure in comparison to conventional radiographs and low per-patient costs.

Evaluation of the prostate imaging reporting and data system for the detection of prostate cancer by the results of targeted biopsy of the prostate.

PurposeThe purpose of this study was to evaluate the magnetic resonance prostate imaging reporting and data system (PI-RADS) for the detection of prostate cancer by the results of magnetic resonance imaging (MRI)–guided biopsy of the prostate as a reference standard. Patients and MethodsIn 55 patients who had undergone MRI-guided biopsy of the prostate, we retrospectively matched every biopsy core with the corresponding lesion in previously acquired endorectal multiparametric MRI including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) at 1.5 T. Two readers blinded to the results of the biopsy evaluated each biopsied lesion according to the PI-RADS scoring system. The results of the targeted biopsy were used as a reference standard. Receiver operating characteristic analysis was performed for statistical analysis. ResultsA total of 113 lesions in the 55 patients were evaluated; 30 lesions were malignant. When evaluated according to the criteria of the PI-RADS scoring system, DCE-MRI revealed a lower area under the receiver operating characteristic curve (AUC) (0.76) compared with T2WI (0.88; P = 0.06) and DWI (0.93; P = 0.004). A sum score combining T2WI, DWI, and DCE-MRI yielded an AUC of 0.93, whereas a sum score combining only T2WI and DWI yielded an AUC of 0.95. In central gland lesions, T2WI showed a numerically higher AUC compared with DWI (0.98 and 0.95), whereas, in peripheral zone lesions, DWI was superior (AUC of 0.93 and 0.73; P = 0.04). An approach assigning a PI-RADS score for T2WI to central gland lesions and for DWI to peripheral zone lesions yielded an AUC of 0.96 and was numerically superior compared with any sequence alone and sum scores combining T2WI and DWI as well as T2WI, DWI, and DCE-MRI. ConclusionsThe PI-RADS scoring system shows a good diagnostic performance for the detection of prostate cancer when using a sum score. However, DCE-MRI does not seem to add significant value when evaluated according to the recommended criteria. Assigning a score for T2WI to central gland lesions and for DWI to peripheral zone lesions might be sufficient for stratification of patients for further diagnostic workup.

Whole-heart coronary magnetic resonance angiography at 1.5 Tesla: does a blood-pool contrast agent improve diagnostic accuracy?

Objectives:To evaluate the impact of the blood-pool contrast agent gadofosveset trisodium on diagnostic accuracy of whole-heart coronary magnetic resonance angiography (CMRA) at 1.5 Tesla. Materials and Methods:Thirty consecutive patients with suspected coronary artery disease underwent free-breathing whole-heart CMRA at 1.5 Tesla. CMRA was performed with a T2-prepared steady-state free precession sequence (unenhanced CMRA) and an inversion-recovery-prepared steady-state free precession sequence after administration of gadofosveset trisodium (contrast-enhanced CMRA). Two readers independently performed a per-segment evaluation of CMRA (8 proximal and mid coronary segments) for detection of significant stenosis (≥50%) using invasive coronary angiography as reference. Disagreement was settled by consensus reading and interobserver variability was assessed using an unweighted kappa statistic. Results:Whole-heart CMRA was successfully performed in 27 patients. The percentage of assessable segments was significantly lower on unenhanced CMRA compared with contrast-enhanced CMRA (Reader 1: 79% [170/216] vs. 89% [192/216], respectively; Reader 2: 73% [157/216] vs. 87% [188/216], respectively; P < 0.001). Intention-to-diagnose analysis of the consensus reading yielded sensitivity, specificity, and diagnostic accuracy of unenhanced versus contrast-enhanced CMRA as follows: 73.1% versus 73.1% (P = 1.0), 68.3% versus 80.2% (P = 0.002), and 68.9% versus 79.3% (P = 0.004), respectively. The kappa value for interobserver agreement was 0.61 (95% confidence interval = 0.50–0.72) for unenhanced CMRA and 0.72 (95% confidence interval = 0.62–0.82) for contrast-enhanced CMRA. Conclusions:The blood-pool contrast agent gadofosveset trisodium increased the number of assessable coronary segments on whole-heart CMRA in comparison to unenhanced whole-heart CMRA. The impact of gadofosveset trisodium on diagnostic accuracy, however, was only minor.

Manganese-based oral contrast agent for liver magnetic resonance imaging: evaluation of the time course and dose response of liver signal intensity enhancement.

Objectives:Recently, an oral contrast agent (CMC-001, CMC Contrast, Lund, Sweden) containing manganese chloride tetrahydrate (MnCl2) as active substance has been introduced for liver magnetic resonance imaging (MRI). The aim of this study was to evaluate the time course and dose response of liver signal intensity (SI) enhancement and liver-lesion contrast (LLC) after administration of 2 doses of CMC-001 corresponding to 0.8 g MnCl2 and 1.6 g MnCl2. Materials and Methods:A total of 20 patients with liver metastases diagnosed by computed tomography were included in this prospective study. Patients were randomly assigned to receive either 0.8 g MnCl2 (n = 11) or 1.6 g MnCl2 (n = 9). MRI was performed precontrast (0 hour) and at 1, 2, 3, and 6 hours after contrast agent administration using a breath-hold T1-weighted gradient echo sequence (GRE). For quantitative analysis, SI was measured in regions of interest in the liver and in representative liver metastases. Liver SI enhancement and LLC were calculated. Area under the curve analysis was performed for liver SI enhancement and LLC in both dose groups. The dose groups were compared with a Wilcoxon rank-sum test for independent samples. Tests for pairwise differences between the time points were performed with paired Wilcoxon signed-rank tests. Results:Area under the curve analysis revealed no statistical significant differences for liver SI enhancement and LLC between the 0.8 and 1.6 g MnCl2 dose group (P = 1.00 and P = 0.94, respectively). Liver parenchyma showed significant SI enhancement until 3 hours after contrast agent administration (median of pooled data from both dose groups: 1 hour, 24.7%; 2 hours, 37.2%; 3 hours, 54.9%; 6 hours, 47.3%). LLC significantly increased until 2 hours after contrast agent administration (median of pooled data from both dose groups: 0 hour, 0.19; 1 hour, 0.29; 2 hours, 0.36; 3 hours, 0.37; 6 hours, 0.36). Liver SI enhancement and LLC showed no significant differences between 3 hours and 6 hours after contrast agent administration (P = 0.75 and P = 0.25, respectively). Mild adverse events occurred in 6 patients (30%) after contrast agent administration. Conclusions:CMC-001 at doses corresponding to 0.8 and 1.6 g MnCl2 offers robust liver SI enhancement with a diagnostic time window for liver MRI between 2 and 6 hours after oral administration.

Whole-body MRI with assessment of hepatic and extraabdominal enhancement after administration of gadoxetic acid for staging of rectal carcinoma.

Background: In TNM staging of rectal cancer by MRI, unspecific extracellular contrast agent Gd-DTPA is established for extrahepatic and vascular enhancement whereas liver-specific gadoxetic acid has proven high accurate detection of liver metastasis. Purpose: To compare intraindividually the qualification and quantification of enhancement in liver parenchyma, abdominal, pulmonary, and pelvic vessels between gadoxetic acid and Gd-DTPA. Material and Methods: Sixteen patients with histologically proven rectal carcinoma (mean age 62.9 years) were imaged twice by MRI. For pretherapeutic staging 10 mL gadoxetic acid (mean dose 0.032 mmol Gd/kg body weight) and for restaging after neoadjuvant therapy Gd-DTPA (0.1 mmol Gd/kg body weight) were administered. The liver was acquired in arterial-dominant and portal venous phases, the thorax and pelvis were depicted in venous phases using three-dimensional T1-weighted sequences. Contrast enhancement was rated by two independent readers and compared by means of multinomial regression analysis using generalized estimating equations. Signal-to-noise ratios were compared by two-sided paired t-tests. Results: Overall contrast enhancement was rated sufficient for diagnosis in all examinations and both contrast agents. Vascular enhancement was rated comparable with exception of the aorta, the peripheral intrahepatic veins, and the central lung vessels (p = 0.0182, p = 0.0053, p = 0.0083, in favor of Gd-DTPA). Quantitative evaluation revealed no statistically significant differences in parenchymal and vascular signal-to-noise ratios with exception of the aorta, and the central pulmonary artery (67.4 vs. 89.3; p = 0.0421, 44.5 vs. 59.5; p = 0.0446 respectively, in favor of Gd-DTPA). Conclusion: The contrast enhancement after gadoxetic acid is comparable to Gd-DTPA and appears suitable for comprehensive TNM-staging by combining high accurate liver-specific phases with efficacious vascular enhancement in the different anatomic regions.

Comparison of MRI with radiography for detecting structural lesions of the sacroiliac joint using CT as standard of reference: results from the SIMACT study

Objective Radiographs of sacroiliac (SI) joints are used for the detection of structural damage in patients with axial spondyloarthritis (axSpA), but are often difficult to interpret. Here, we address the question how the T1-weighted MRI (T1w MRI) sequence compares with radiography for SI joints’ structural lesions using low-dose CT as the standard of reference. Methods Radiographs, T1w MRI and low-dose CT of the SI joints from 110 patients (mean age 36.1 (19–57) years, 52% males and 48% females; 53% with axSpA, 21 non-radiographic axSpA and 32% radiographic axSpA, 47% with non-SpA) referred to the rheumatologist because of unclear chronic back pain, but possible axSpA, were scored for structural lesions (erosions, sclerosis, joint space changes and an overall impression of positivity). Results Using low-dose CT as the standard of reference, T1w MRI showed markedly better sensitivity with significantly more correct imaging findings compared with radiography for erosions (79% vs 42%; p=0.002), joint space changes (75% vs 41%; p=0.002) and overall positivity (85% vs 48%; p=0.001), respectively, while there were no differences between X-rays and MRI-T1 sequence regarding specificity (>80% for all scores). Only for sclerosis, MRI-T1 was inferior to radiography (sensitivity 30% vs 70%, respectively), however, not statistically significant (p=0.663). Conclusions T1w MRI was superior to radiography in the detection of structural lesion of the SI joints in patients with axSpA. Future studies should focus on finding an agreement on the definition of MRI-T1 positivity.

Low Dose Computed Tomography for 3D Planning of Total Hip Arthroplasty: Evaluation of Radiation Exposure and Image Quality.

Objective The aim of the study was to compare radiation exposure and image quality between dedicated computed tomography (CT) protocols for preoperative total hip arthroplasty (THA) planning. Methods Three protocols with automated tube current modulation using 64-slice (n = 177) and 128-slice CT scanners without (n = 129) and with automated tube voltage preselection (n = 84) were compared. Results All 390 CTs were of sufficient quality for THA planning. Mean DLP was 235.0 mGy*cm (effective dose 2.8 mSv). Lowest radiation exposure (2.5 mSv) was seen with automated voltage preselection and the algorithms selection was 100 kV (90.5% of patients) and 120 kV. Lowest image noise was seen in the highest dose group (3.1 mSv, 128-slice CT fixed tube voltage). A significant difference in cortical bone radiodensity was seen between 100 kV and 120 kV (P < 0.0001). Conclusions Preoperative pelvic CT for THA planning is possible with very low radiation dose and reliable quality. Automated voltage preselection further decreases the effective dose by 18.2%.

MRI-guided core needle biopsy of the prostate: acceptance and side effects.

PURPOSE We aimed to study side effects, complications, and patient acceptance of magnetic resonance imaging-guided real-time biopsy (MRI-GB) of the prostate. METHODS Fifty-four men (49-78 years) with elevated prostate-specific antigen after at least one negative systematic transrectal ultrasound-guided biopsy (TRUS-GB) were included in a prospective clinical study. Suspicious areas on images were selectively sampled by obtaining a median of four specimens (range, 1-9 specimens) using MRI-GB. In TRUS-GB, a median of 10 specimens (range, 6-14 specimens) were obtained. Telephone interviews were conducted one week after outpatient MRI-GB, asking patients about pain and side effects (hematuria, hemospermia, rectal bleeding, fever, and chills) of the two biopsy procedures and which of the two procedures they preferred. Multinomial regression analysis and Fishers exact test was used to test for differences. RESULTS MRI-GB was preferred by 65% (35/54), and 82% (44/54) would undergo MRI-GB again. Pain intensity (P = 0.005) and bleeding duration (P = 0.004) were significantly lower for MRI-GB compared with TRUS-GB. Hematuria was less common after MRI-GB compared with TRUS-GB (P = 0.006). A high correlation was given between bleeding intensity and bleeding duration for TRUS-GB (r=0.77) and pain intensity and pain duration for MRI-GB (r=0.65). Although hemospermia, rectal hemorrhage, fever, and chills were less common in MRI, they showed no statistically significant difference. CONCLUSION MRI-GB of the prostate seems to have fewer side effects and less pain intensity than TRUS-GB and was preferred by the majority of patients.

Maximizing information from routine staging computed tomography in functional neuroendocrine neoplasms: are there findings indicating the presence of carcinoid heart disease?

Purpose The aim of this study was to evaluate signs of right-sided heart dysfunction on staging computed tomography (CT) as indirect indicators of carcinoid heart disease. Patients and Methods Patients with functionally active neuroendocrine neoplasm and different grades of tricuspid valve regurgitation (TR) were identified. Two readers independently reviewed contrast-enhanced staging CT performed within 90 days before or after echocardiography. Logistic regression and receiver operating analyses were used to asses the predictive value of right ventricle–left ventricle ratio (RV-LV ratio), ventricular septal bowing, retrograde contrast filling of the hepatic veins during contrast injection, and time to aortal enhancement greater than 100 Hounsfield units during bolus tracking for TR. Results Forty-four examinations were evaluated (11 with TR = 0, 16 with TR = 1, 9 with TR = 2, and 8 with TR = 3). Right ventricle–LV ratio was found to predict TR less than or equal to 1 versus TR greater than 1 (P = 0.0188) and TR less than or equal to 1 versus TR equals 2 (P = 0.0082). A prolonged time to aortal enhancement greater than 100 Hounsfield units during bolus tracking predicted TR less than or equal to 1 versus TR greater than 1 (P = 0.0077). Area under the curve for RV-LV ratio was 0.86 when differentiating TR less than or equal to 1 versus TR equals 2. With a cutoff of 1.07, sensitivity was 0.89, and specificity was 0.72. Conclusions In patients with functionally active neuroendocrine neoplasm, an RV-LV ratio of more than 1.07 predicted TR with a relatively high sensitivity and moderate specificity and thus could serve as an indicator of subclinical carcinoid heart disease on routine staging CT.

MR-guided biopsy of the prostate: Comparison of diagnostic specimen quality with 18G and 16G biopsy needles

PURPOSE To evaluate specimen quality and diagnostic differences between magnetic resonance (MR) compatible 16 G and 18 G biopsy needles in MR-guided biopsy (MRGB) of the prostate. MATERIALS AND METHODS Semiautomatic MR compatible biopsy needles with a diameter of 16 G (Group A) or 18 G (Group B) were used to perform MRGB in 88 patients with suspected prostate cancer. After embedding and staining, length and width of all specimens (140 cores in Group A, 143 in Group B) were measured. Fragmentation, squeezing artifacts, and overall evaluability were evaluated using a quality score from 0 (no tissue) to 3 (optimal tissue quality). Groups were statistically compared; p-values <0.05 were regarded as significant. RESULTS Demographic data were not significantly different between Group A and B with a mean age of 63 ± 7.3 and 67 ± 5.7 years; and a mean prostate-specific antigen of 12.6 ± 10.3 ng/ml and 13.8 ± 11.6 ng/ml, respectively (p=0.70). Area of longitudinally sectioned histological specimens was significantly larger in Group A than in Group B with 9.38 mm(2) (8.74; 10.02) and 7.95 mm(2) (7.32; 8.59), respectively (p=0.002). However, there were significantly more cores without prostate tissue with 18 cores (12.9%) versus 3 cores (2.1%) in Groups A and B, respectively (p=0.004). Fragmentation, squeezing artifacts, and overall evaluability were not statistically different between the two groups. The rate of prostate cancer in the cores was also not significantly different between Groups A and B (22.1% and 24.5%; p=0.77). CONCLUSION 16 G biopsy needles do not provide a relevant diagnostic advantage over 18 G needles in MRGB. Therefore, use of 18 G needles is not discouraged and may even be preferred as it is not expected to result in a relevant degradation of specimen quality or compromise in prostate cancer detection rate.