Fetal 4D flow MRI of the great thoracic vessels at 3 Tesla using Doppler-ultrasound gating: a feasibility study

OBJECTIVES

To evaluate the feasibility of Doppler-ultrasound (DUS)-gated 4D flow MRI of the fetal great thoracic vessels at 3T in a clinical setting.

METHODS

Sixteen consecutive fetuses (range 30⁺⁴-38⁺⁵ weeks) with (n = 11) and without (n = 5) cardiovascular anomalies underwent 4D flow MRI of the great thoracic vessels at 3T. Direct fetal cardiac gating was obtained using a MR-compatible DUS device. 4D flow MRI-based visualisation and quantification of four target regions (ascending aorta (AAo), descending aorta (DAo), main pulmonary artery (MPA), and ductus arteriosus (DA)) were performed using dedicated software.

RESULTS

Fetal 4D flow MRI of the great thoracic vessels was successful in 12/16 fetuses (75%) by adopting clinical 4D flow MR protocols in combination with direct fetal cardiac DUS-gating. Four datasets were excluded due to artefacts by fetal movement or maternal breathing. 4D flow MRI-derived time-velocity curves revealed typical arterial blood flow patterns in the aorta. 4D flow quantification was achieved for the pre-defined target regions. Average velocity and flow volume were 21.1 ± 5.2 cm/s and 6.0 ± 3.1 mL/s in the AAo, 24.3 ± 6.7 cm/s and 8.4 ± 3.7 mL/s in the DAo, 21.9 ± 6.4 cm/s and 7.8 ± 4.2 mL/s in the MPA, and 23.4 ± 4.7 cm/s and 5.9 ± 3.6 mL/s in the DA, respectively.

CONCLUSIONS

Combination of DUS-gating of the fetal heart and 4D flow MRI allows comprehensive visualisation and quantification of haemodynamics in the fetal great thoracic vessels. DUS-gated fetal 4D flow MRI may provide a new diagnostic approach for prenatal assessment of blood flow haemodynamics.

KEY POINTS

• Fetal cardiac Doppler-ultrasound (DUS) gating and 4D flow MRI can be successfully combined. • DUS-gated fetal 4D flow MRI allowed visualisation and evaluation of streamline directionality, illustration of blood flow variations, and pulsatile arterial waveforms in the target vessels. • 4D flow MRI-based visualisation and quantification of the fetal great thoracic vessels were successful and flow metrics agreed with echocardiographic reference values.

Correlation of T2* relaxation times of the retropatellar cartilage with tibial tuberosity-trochlea groove distance in professional soccer players

The tibial tuberosity–trochlear groove (TT–TG) distance is a radiographic measurement that is used to quantify malalignment of the patellofemoral joint (PFJ) in cross-sectional imaging. There is an ongoing debate about the impact of the TT–TG-distance on lateral patellar instability and the initiating of cartilage degeneration. In this prospective study, the association of T2* relaxation times and TT–TG distances in professional soccer players was analyzed. 36 knees of 18 professional soccer players (age: 21 ± 2.8 years) were evaluated. Participants underwent knee MRI at 3 T. For qualitative image analysis, fat-saturated 2D PD-weighted Fast Spin Echo (FSE) and T1-weighted FSE sequences were used. For quantitative analysis, T2* measurements in 3D data acquisitions were performed. In a qualitative analysis there was no structural cartilage damage and no abnormalities of the patellar and trochlea shape. The highest T2* values (26.7 ± 5.9 ms) were observed in the central compartment of the patella. The mean TT–TG distance was 10 ± 4 mm (range 3–20 mm). There was no significant correlation between TT–TG distance and T2* relaxation times in all three compartments of the retropatellar cartilage. Our study shows that so long as patellar and trochlear morphology is normal, TT–TG distance alone does not affect the tissue structure of the retropatellar cartilage in professional soccer players.

Relevant bleeding diathesis due to acquired factor XIII deficiency

Acquired factor XIII (FXIII) deficiency is associated with reduced clot firmness and increased bleeding in patients undergoing major surgery. In contrast, only limited information is available on the haemostatic relevance of acquired FXIII deficiency in non-surgical patients.

An 81-year-old patient, who had experienced acute type-A dissection of the aorta eight years earlier, presented with a 3-year history of progressive mucocutaneous and softtissue bleeding. Diagnostic work-up was unremarkable for global coagulation tests, but FXIII and alpha2-antiplasmin were decreased to 33% and 27%, respectively, while plasma D-dimer was elevated to > 35 mg/l. A FXIII inhibitor was excluded by mixing studies. CT scanning revealed a massively elongated and progressively dilated aorta with a false lumen reaching from the left carotid artery to the iliac bifurcation. Bleeding control was achieved by single doses of FXIII at 20-30 IU/ kg body weight and tailored oral tranexamic acid.

Acquired FXIII deficiency with activity levels of 30–35% may confer a severe bleeding tendency in non-surgical patients, especially in the context of increased thrombin an fibrin generation.

Noise reduction angiographic imaging technology reduces radiation dose during bronchial artery embolization

PURPOSE

Comparison of radiation doses in patients undergoing angiographic bronchial artery embolization (BAE) before and after a noise reduction imaging technology upgrade.

METHODS

We performed a retrospective study of 70 patients undergoing BAE. Procedures were performed before (n=32) and after (n=38) the technology upgrade containing additional filters and improved image-processing. Cumulative air kerma (AK), cumulative dose area product (DAP), number of exposure frames, total fluoroscopy time and amount of contrast agent were recorded. Mean values were calculated and compared using two-tailed t-tests. DSA image quality was assessed independently by two blinded readers and compared using the Wilcoxon signed-rank test.

RESULTS

Using the new technology resulted in a significant reduction of 59% in DAP (149.2 (103.1-279.1) vs. 54.8 (38.2-100.7) Gy*cm², p<0.001) and a significant reduction of 60% for AK (1.3 (0.6-1.9) vs. 0.5 (0.3-0.9) Gy, p<0.001) in comparison to procedures before the upgrade. There was no significant difference between the number of exposure frames in both groups (251±181 vs. 254±133 frames, p=0.07), time of fluoroscopy (28.8 (18.5-50.4) vs. 28.1 (23.3-38.7) min, p=0.73), or the amount of contrast agent used (139.5±70.8 vs. 163.1±63.1ml, p=0.11). No significant difference regarding image quality could be detected (3 (2,3) vs. 3 (2-4), p=0.64).

CONCLUSIONS

The new angiographic noise reduction technology significantly decreases the radiation dose during bronchial artery embolization without compromising image quality or increasing time of fluoroscopy or contrast volume.

Radiation dose reduction during transjugular intrahepatic portosystemic shunt implantation using a new imaging technology

OBJECTIVE

To compare patient radiation dose in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) implantation before and after an imaging-processing technology upgrade.

METHODS

In our retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), total fluoroscopy time and contrast agent were collected from an age- and BMI-matched collective of 108 patients undergoing TIPS implantation. 54 procedures were performed before and 54 after the technology upgrade. Mean values were calculated and compared using two-tailed t-tests. Two blinded, independent readers assessed DSA image quality using a four-rank likert scale and the Wilcoxcon test.

RESULTS

The new technology demonstrated a significant reduction of 57% of mean DAP (402.8 vs. 173.3Gycm², p<0.001) and a significant reduction of 58% of mean AK (1.7 vs. 0.7Gy, p<0.001) compared to the precursor technology. Time of fluoroscopy (26.4 vs. 27.8min, p=0.45) and amount of contrast agent (109.4 vs. 114.9ml, p=0.62) did not differ significantly between the two groups. The DSA image quality of the new technology was not inferior (2.66 vs. 2.77, p=0.56).

CONCLUSIONS

In our study the new imaging technology halved radiation dose in patients undergoing TIPS maintaining sufficient image quality without a significant increase in radiation time or contrast consumption.

Age-related differences in the activity of arterial mineral deposition and regional bone metabolism: a 18F-sodium fluoride positron emission tomography study

Functional (18)F-fluoride PET demonstrated an inverse relationship between the activity of arterial mineral deposition and regional bone metabolism. While bone metabolism decreases with age, the activity of arterial mineral deposition increases.

INTRODUCTION

The extent of arterial calcification increases with age, whereas bone mineral density decreases, evidencing a well-known inverse correlation on morphological basis. The aim of this study was to evaluate the functional relationship between the activity of arterial mineral deposition and regional bone metabolism as assessed by (18)F-sodium fluoride (NaF) PET/CT.

METHODS

Three hundred four subjects were examined by (18)F-NaF PET/CT. Tracer accumulation in the femoral arteries was analyzed both qualitatively and semiquantitatively by measuring the blood-pool-corrected standardized uptake value (target-to-background ratio). Uptake was compared with cardiovascular risk factors (RFs), calcified plaque burden, and regional bone metabolism as assessed by PET/CT.

RESULTS

The activity of arterial mineral deposition significantly increased with age (p < 0.001), whereas regional bone metabolism significantly decreased (p < 0.001). There was a significant inverse correlation between bone metabolism and arterial mineral deposition (unadjusted, p < 0.001); that association was not significant (p = 0.79) when controlled for age and other RFs. Both high activity of arterial mineral deposition and low bone metabolism were significantly associated with cardiovascular events and other RFs.

CONCLUSION

(18)F-NaF PET/CT provides a tool to visualize and quantify the activity of arterial mineral deposition and regional bone metabolism. In this study, we observed an inverse correlation between the activity of arterial mineral deposition and regional bone metabolism. While the activity of arterial mineral deposition significantly increases with age, regional bone metabolism decreases.

Intra-individual comparison of magnesium citrate and sodium phosphate for bowel preparation at CT colonography: automated volumetric analysis of residual fluid for quality assessment

AIM

To perform an objective, intra-individual comparison of residual colonic fluid volume and attenuation associated with the current front-line laxative magnesium citrate (MgC) versus the former front-line laxative sodium phosphate (NaP) at CT colonography (CTC).

MATERIALS AND METHODS

This retrospective Health Insurance and Portability and Accountability Act-compliant study had institutional review board approval; informed consent was waived. The study cohort included 250 asymptomatic adults (mean age at index 56.1 years; 124 male/126 female) who underwent CTC screening twice over a 5 year interval. Colon catharsis at initial and follow-up screening employed single-dose NaP and double-dose MgC, respectively, allowing for intra-patient comparison. Automated volumetric analysis of residual colonic fluid volume and attenuation was performed on all 500 CTC studies. Colonic fluid volume <200 ml and mean attenuation between 300-900 HU were considered optimal. Paired t-test and McNemar's test were used to compare differences.

RESULTS

Residual fluid volumes <200 ml were recorded in 192 examinations (76.8%) following MgC and in 204 examinations (81.6%) following NaP (p = 0.23). The mean total residual fluid volume was 155 ± 114 ml for MgC and 143 ± 100 ml for NaP (p = 0.01). The attenuation range of 300-900 HU was significantly more frequent for MgC (n = 220, 88%) than for NaP (n = 127, 50.8%; p < 0.001). Mean fluid attenuation was significantly lower for MgC (700 ± 165 HU) than for NaP (878 ± 155 HU; p < 0.001). Concomitant presence of both optimal fluid volume and attenuation was significantly more frequent for MgC 65.2% than for NaP (38%; p < 0.001).

CONCLUSIONS

Objective intra-individual comparison using automated volumetric analysis suggests that the replacement of NaP by MgC as the front-line laxative for CTC has not compromised overall examination quality.

Dural ectasia in Loeys-Dietz syndrome: comprehensive study of 30 patients with a TGFBR1 or TGFBR2 mutation

The purpose of this study was to assess the frequency, severity, and clinical associations of dural ectasia (DE) in Loeys-Dietz syndrome (LDS). Database analysis of three German metropolitan regions identified 30 patients with LDS and TGFBR1 mutation in 6 and a TGFBR2 mutation in 24 individuals (17 men; mean age: 31 ± 19 years), as well as 60 age and sex-matched control patients with Marfan syndrome carrying a FBN1 mutation. DE was present in 22 patients with LDS (73%), and it related to skeletal score points (p = 0.008), non-skeletal score points (p < 0.001), and to the presence of ≥7 systemic score points (p = 0.010). Similarly, the severity of DE was related to body height (p = 0.010) and non-skeletal score points (p = 0.004). Frequency (p = 0.131) and severity of DE (p = 0.567) was similar in LDS and Marfan syndrome. DE is a manifestation of LDS that occurs with similar frequency and severity as in Marfan syndrome. Severity of DE may serve as a marker of the overall connective tissue disease severity. LDS may be considered in patients with DE.

[Instructions for original radiological research manuscripts]

Many scientific manuscripts submitted for publication are flawed by conceptual mistakes. This leads to the rejection of potentially valuable scientific data in renowned journals. This article intends to guide young researchers with respect to writing a well-structured scientific radiological manuscript.

Shiga toxin-producing E. coli O104:H4 outbreak 2011 in Germany: radiological features of enterohemorrhagic colitis

PURPOSE

In 2011 a nationwide outbreak of Shiga toxin-producing E. coli (STEC) O104:H4 infection occurred in Germany with severe hemorrhagic colitis and hemolytic-uremic syndrome (HUS). We defined abdominal radiologic findings in these patients and correlated them with clinical parameters.

MATERIALS AND METHODS

23 patients (7 men; age: 48 ± 19 years) with O104:H4 colitis and/or HUS received abdominal CT (n = 12) or radiographs (n = 11). Colonic distension, air-fluid levels, and free intraabdominal air were assessed. Colonic wall thickening, contrast enhancement, pericolic stranding, and ascites were evaluated on CT. Laboratory parameters and clinical presentation were reviewed. Chi-square test, Student's t-test, McNemar's test and Spearman correlation were performed.

RESULTS

Colonic lumen distension was seen in 16/23 patients (69.6 %). The ascending colon (11/23 patients; 47.8 %) and transverse colon (12/23 patients; 52.2 %) were dilated significantly more often (p = 0.006 and p = 0.003, respectively) than the descending colon (1/23; 4.3 %). All 12 patients undergoing CT scanning had abnormally thickened colonic wall segments, 3 (25 %) had pancolic involvement and 9 (75 %) had segmental involvement. The descending colon was predominantly affected (11/12 patients; 91.7 %) and thickened significantly more often than other colonic segments (p < 0.001).

CONCLUSION

The segmental type of STEC O104:H4 colitis mainly affects the descending colon with upstream distension of the transverse/ascending colon and differs from other types of colitis.

Fractures of the thoracic spine in patients with minor trauma: comparison of diagnostic accuracy and dose of biplane radiography and MDCT

OBJECTIVES

To investigate the accuracy of biplane radiography in the detection of fractures of the thoracic spine in patients with minor trauma using multidetector computed tomography (MDCT) as the reference and to compare the dose of both techniques.

METHODS

107 consecutive trauma patients with suspected fractures of the thoracic spine on physical examination were included. All had undergone biplane radiography first, followed by a MDCT scan between October 2008 and October 2012. A fourfold table was used for the classification of the screening test results. Both the Chi-square test (χ(2)) and the mean dose-length product (DLP) were used to compare the diagnostic methods.

RESULTS

MDCT revealed 77 fractures in 65/107 patients (60.7%). Biplane radiography was true positive in 32/107 patients (29.9%), false positive in 19/107 patients (17.8%), true negative in 23/107 (21.5%) and false negative in 33/107 patients (30.8%), showing a sensitivity of 49.2%, a specificity of 54.7%, a positive predictive value (PPV) of 62.7%, a negative predictive value (NPV) of 41.1%, and an accuracy of 51.4%. The presence of a fracture on biplane radiography was highly statistical significant, if this was simultaneously proven by MDCT (χ(2)=7.6; p=0.01). None of the fractures missed on biplane radiography was unstable. The mean DLP on biplane radiography was 14.5mGycm (range 1.9-97.8) and on MDCT 374.6mGycm (range 80.2-871).

CONCLUSIONS

The sensitivity and the specificity of biplane radiography in the diagnosis of fractures of the thoracic spine in patients with minor trauma are low. Considering the wide availability of MDCT that is usually necessary for taking significant therapeutic steps, the indication for biplane radiography should be very restrictive.

Relevant bleeding diathesis due to acquired factor XIII deficiency

BACKGROUND

Acquired factor XIII (FXIII) deficiency is associated with reduced clot firmness and increased bleeding in patients undergoing major surgery. In contrast, only limited information is available on the haemostatic relevance of acquired FXIII deficiency in non-surgical patients.

CASE REPORT

An 81-year-old patient, who had experienced acute type-A dissection of the aorta eight years earlier, presented with a 3-year history of progressive mucocutaneous and soft-tissue bleeding. Diagnostic work-up was unremarkable for global coagulation tests, but FXIII and alpha2-antiplasmin were decreased to 33% and 27%, respectively, while plasma D-dimer was elevated to > 35 mg/l. A FXIII inhibitor was excluded by mixing studies. CT scanning revealed a massively elongated and progressively dilated aorta with a false lumen reaching from the left carotid artery to the iliac bifurcation. Bleeding control was achieved by single doses of FXIII at 20-30 IU/kg body weight and tailored oral tranexamic acid.

CONCLUSION

Acquired FXIII deficiency with activity levels of 30-35% may confer a severe bleeding tendency in non-surgical patients, especially in the context of increased thrombin an fibrin generation.

[Modern imaging techniques in patients with multiple myeloma]

Imaging studies are essential for both diagnosis and initial staging of multiple myeloma, as well as for differentiation from other monoclonal plasma cell diseases. Apart from conventional radiography, a variety of newer imaging modalities including whole-body low-dose-CT, whole-body MRI and 18F-FDG PET/CT may be used for detection of osseous and extraosseous myeloma manifestations. Despite of known limitations such as limited sensitivity and specificity and the inability to detect extraosseous lesions, conventional radiography still remains the gold standard for staging newly diagnosed myeloma, partly due to its wide availability and low costs. Whole-body low-dose CT is increasingly used due to its higher sensitivity for the detection of osseous lesions and its ability to diagnose extraosseous lesions, and is replacing conventional radiography at selected centres. The highest sensitivity for both detection of bone marrow disease and extraosseous lesions can be achieved with whole-body MRI or 18F-FDG PET/CT. Diffuse bone marrow infiltration may be visualized by whole-body MRI with high sensitivity. Whole-body MRI is at least recommended in all patients with normal conventional radiography and in all patients with an apparently solitary plasmacytoma of bone. To obtain the most precise readings, optimized examination protocols and dedicated radiologists and nuclear medicine physicians familiar with the complex and variable morphologies of myeloma lesions are required.

Improved agreement between experienced and inexperienced observers using a standardized evaluation protocol for cardiac volumetry and infarct size measurement

PURPOSE

To study the agreement between experienced and inexperienced observers before and after training using a standardized evaluation protocol for cardiac magnetic resonance imaging (CMR) measurements of left ventricular (LV) volumes, mass and infarct size.

MATERIALS AND METHODS

First, 10 CMR studies from patients with myocardial infarction were analyzed by 2 experienced and 4 inexperienced observers in respect to end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), LV mass and infarct size. Subsequently, the inexperienced observers were trained using a standardized evaluation protocol. Thereafter, all observers analyzed another 10 CMR studies.

RESULTS

Before training the relative difference between experienced and inexperienced observers was -4.3±8.2% for EDV, -13.3±14.2% for ESV, 5.9±8.2% for EF, -12.2±10.9% for LV mass and -27.0±29.0% for infarct size in gram. After training, agreement significantly improved to 0.2±8.8% for EDV (p<0.05), -2.1±10.9 for ESV (p<0.01), 1.5±6.9% for EF (p<0.05), and -3.6±17.1% for infarct size (p<0.0001), but no improvement was seen for LV mass (-11.2±7.9, p=0.64). A slice based analysis showed, that the variable inclusion of the most basal and apical slices were mainly responsible for the low agreement of the measurements before training.

CONCLUSION

Training using a standardized evaluation protocol significantly improved the agreement between experienced and inexperienced observers for important CMR parameters. The proposed evaluation protocol can be used for training to improve the reproducibility of CMR measurements.