[Imaging of tumor predisposition syndromes]

CLINICAL ISSUE

Tumor predisposition syndromes (TPS) are a heterogeneous group of genetic cancers. About 10% of the approximately 2200 malignancies in the childhood in Germany develop due to an inherited disposition, whereby TPS may be underdiagnosed. The focus of this review is set on imaging of Li-Fraumeni syndrome, neurofibromatoses, tuberous sclerosis, overgrowth, and neuroendocrine syndromes.

STANDARD RADIOLOGICAL METHODS

In order to detect tumors at an early stage, screening at specific time intervals for each TPS are required. Ultrasonography and magnetic resonance imaging (MRI), especially whole-body MRI, are particularly important imaging modalities.

METHODOLOGICAL INNOVATIONS

Innovative MRI techniques can increase image quality and patient comfort. MRI acquisition time can be significantly reduced through optimized acceleration factors, motion robust radial sequences and joint acquisition and readout of multiple slices during excitation. Thus, shorter MRI examinations can be performed in younger children without anesthesia.

PRACTICAL RECOMMENDATION

Regular screening with ultrasound and MRI can reduce the morbidity and mortality of the patients affected with TPS.

[Imaging of abdominal tumors in childhood and adolescence : Part I: Background, hepatic, splenic and pancreatic tumors]

In comparison to adult patients, other specific entities of abdominal tumors occur in childhood and adolescence. These include malignant tumors originating from embryonic tissue, such as hepatoblastoma. Some of the abdominal tumors are already diagnosed prenatally or in neonates. Sonography functions as the primary radiological basic diagnostics of pediatric abdominal space-occupying lesions, if necessary supplemented by administration of ultrasound contrast medium or the implementation of novel techniques (e.g. innovative Doppler and elastography procedures). Magnetic resonance imaging (MRI) is used for a comprehensive and detailed depiction of the tumors including the question of resectability and vascular supply. Various weighting and different MRI sequences are used in order to be able to assess the signal behavior of the tumor and therefore the possible presence of calcification, necrosis or hemorrhage, the behavior of dynamic contrast enhancement, and the presence and extent of diffusion disorders. This information is decisive in order to be able to assess the entity and malignancy of the abdominal space-occupying lesion. Rare but relevant tumors with respect to the entity occur in childhood and adolescence in the abdominal organs liver, spleen and pancreas.

MRI of cystic fibrosis lung manifestations: sequence evaluation and clinical outcome analysis

AIM

To evaluate different magnetic resonance imaging (MRI) sequences for diagnosis of pulmonary manifestations of cystic fibrosis (CF) in comparison to chest computed tomography (CT), including an extended outcome analysis.

MATERIALS AND METHODS

Twenty-eight patients with CF (15 male, 13 female, mean age 30.5±9.4 years) underwent CT and MRI of the lung. MRI (1.5 T) included different T2- and T1-weighted sequences: breath-hold HASTE (half Fourier acquisition single shot turbo spin echo) and VIBE (volumetric interpolated breath-hold examination, before and after contrast medium administration) sequences and respiratory-triggered PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) sequences with and without fat signal suppression, and perfusion imaging. CT and MRI images were evaluated by the modified Helbich and the Eichinger scoring systems. The clinical follow-up analysis assessed pulmonary exacerbations within 24 months.

RESULTS

The highest concordance to CT was achieved for the PROPELLER sequences without fat signal suppression (concordance correlation coefficient CCC of the overall modified Helbich score 0.93 and of the overall Eichinger score 0.93). The other sequences had the following concordance: PROPELLER with fat signal suppression (CCCs 0.91 and 0.92), HASTE (CCCs 0.87 and 0.89), VIBE (CCCs 0.84 and 0.85) sequences. In the outcome analysis, the combined MRI analysis of all five sequences and a specific MRI protocol (PROPELLER without fast signal suppression, VIBE sequences, perfusion imaging) reached similar correlations to the number of pulmonary exacerbations as the CT examinations.

CONCLUSION

An optimum lung MRI protocol in patients with CF consists of PROPELLER sequences without fat signal suppression, VIBE sequences, and lung perfusion analysis to enable high diagnostic efficacy and outcome prediction.

Dose reduction in paediatric cranial CT via iterative reconstruction: a clinical study in 78 patients

AIM

To assess how adaptive statistical iterative reconstruction (ASIR) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT) in children.

MATERIALS AND METHODS

Non-contrast cranial CT acquired in 78 paediatric patients (age 0-12 years) were evaluated. The images were acquired and processed using four different protocols: Group A (control): 120 kV, filtered back projection (FBP), n=18; Group B: 100 kV, FBP, n=22; Group C: 100 kV, scan and reconstruction performed with 20% ASIR, n=20; Group D1: 100 kV, scan and reconstruction performed with 30% ASIR, n=18; Group D2: raw data from Group D1 reconstructed using a blending of 40% ASIR and 60% FBP, n=18. The effective dose was calculated and the image quality was assessed quantitatively and qualitatively.

RESULTS

Compared to Group A, Groups C and D1/D2 showed a significant reduction of the dose-length product (DLP) by 34.4% and 64.4%, respectively. All experimental groups also showed significantly reduced qualitative levels of noise, contrast, and overall diagnosability. Diagnosis-related confidence grading showed Group C to be adequate for everyday clinical practice. Quantitative measures of Groups B and C were comparable to Group A with only few parameters compromised. Quantitative scores in Groups D1 and D2 were mainly lower compared to Group A, with Group D2 performing better than Group D1. Group D2 was considered adequate for follow-up imaging of severe acute events such as bleeding or hydrocephalus.

DISCUSSION

The use of ASIR combined with low tube voltage may reduce radiation significantly while maintaining adequate image quality in non-contrast paediatric cCT.

Reducing Radiation Dose in Adult Head CT using Iterative Reconstruction - A Clinical Study in 177 Patients

PURPOSE

To assess how ASIR (adaptive statistical iterative reconstruction) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT).

MATERIALS AND METHODS

Non-contrast emergency CT scans of the head acquired in 177 patients were evaluated. The scans were acquired and processed using four different protocols: Group A (control): 120 kV, FBP (filtered back projection) n = 71; group B1: 120 kV, scan and reconstruction performed with 20 % ASIR (blending of 20 % ASIR and 80 % FBP), n = 86; group B2: raw data from group B1 reconstructed using a blending of 40 % ASIR and 60 % FBP, n = 74; group C1: 120 kV, scan and reconstruction performed with 30 % ASIR, n = 20; group C2: raw data from group C1 reconstructed using a blending of 50 % ASIR and 50 % FBP, n = 20. The effective dose was calculated. Image quality was assessed quantitatively and qualitatively.

RESULTS

Compared to group A, groups B1/2 and C1/2 showed a significantly reduced effective dose of 40.4 % and 73.3 % (p < 0.0001), respectively. Group B1 and group C1/2 also showed significantly reduced quantitative and qualitative image quality parameters. In group B2, quantitative measures were comparable to group A, and qualitative scores were lower compared to group A but higher compared to group B1. Diagnostic confidence grading showed groups B1/2 to be adequate for everyday clinical practice. Group C2 was considered acceptable for follow-up imaging of severe acute events such as bleeding or subacute stroke.

CONCLUSION

Use of ASIR makes it possible to reduce radiation significantly while maintaining adequate image quality in non-contrast head CT, which may be particularly useful for younger patients in an emergency setting and in follow-up.

KEY POINTS

ASIR may reduce radiation significantly while maintaining adequate image quality. cCT protocol with 20 % ASIR and 40 %ASIR/60 %FBP blending is adequate for everyday clinical use. cCT protocol with 30 % ASIR and 50 %ASIR/50 %FBP blending is adequate for follow-up imaging

Impact of magnification views on the characterization of microcalcifications in digital mammography

PURPOSE

To evaluate the additional benefit of true geometric (air-gap) magnification views for the characterization of microcalcifications in digital mammography.

MATERIALS AND METHODS

After ethical approval, we retrospectively reviewed patient records to identify 100 patients with suspicious microcalcifications (35 malignant, 65 benign) who had a standard digital mammography and an additional digital magnification view in the same projection within three months. All images were obtained using an amorphous silicon-based full-field digital system (Senographe 2000 D, GE Healthcare, Chalfont St. Giles, UK). Images were independently analyzed by six board-certified radiologists. The probability of malignancy was estimated using first standard contact mammography alone (MG) and then mammography in combination with the magnification view (MG+MAG) using a modified Breast Imaging Reporting and Data System (BI-RADS) classification system and a percentage scale. Results were compared using receiver operating characteristic (ROC) analysis. In addition, readers assessed the subjective visibility of the calcifications.

RESULTS

For all six readers combined, the area under the curve (AUC) was 0.664 ± 0.052 for MG and 0.813 ± 0.042 for MG + MAG, resulting in a statistically significant improvement of 0.148 ± 0.120. Each reader had a higher AUC for MG + MAG than MG, with the improvement being statistically significant in four of the six readers. In 76.34 % of the cases, MG + MAG resulted in better visibility of calcifications compared with mammography alone. In 33 % slightly more and in 39 % significantly more calcifications were found.

CONCLUSION

Even in digital mammography with the option of using electronic magnification (zoom) at the viewing workstation, true geometric (air-gap) magnification views remain important for the visibility and correct classification of microcalcifications and for the assessment of their extent.

Cost comparison of nerve root infiltration of the lumbar spine under MRI and CT guidance

OBJECTIVES

To compare the costs of CT- and MR-guided lumbosacral nerve root infiltration for minimally invasive treatment of low back pain and radicular pain.

METHODS

Ninety patients (54 men, 36 women; mean age, 45.5 ± 12.8 years) underwent MR-guided single-site periradicular lumbosacral nerve root infiltration with 40 mg of triamcinolone acetonide. A further 91 patients (48 men, 43 women; mean age, 59.1 ± 13.8 years) were treated under CT fluoroscopy guidance. Prorated costs of equipment use (purchase, depreciation and maintenance), staff costs based on involvement times and expenditure for disposables were identified for MR- and CT-guided procedures.

RESULTS

Mean intervention time was 20.6 min (14-30 min) for MR-guided and 14.3 min (7-32 min) for CT-guided treatment. The average total costs per patient were €177 for MR-guided and €88 for CT-guided interventions. These consisted of (MR/CT guidance) €93/29 for equipment use, €43/35 for staff and €41/24 for disposables.

CONCLUSIONS

Lumbosacral nerve root infiltration using MRI guidance is still about twice as expensive as infiltration using CT guidance. Given the advantages of no radiation exposure and possible future decrease in prices for MRI devices and MR-compatible injection needles, MR-guided nerve root infiltration may become a promising alternative to the CT-guided procedure.

KEY POINTS

• MR-guided nerve root infiltration therapy is now technically and clinically established. • Costs using MRI guidance are still about double those for CT guidance. • MR guidance involves no radiation exposure to patients and personnel. • MR-guided nerve root infiltration may become a promising alternative to CT.

Treatment of osteoid osteoma using CT-guided radiofrequency ablation versus MR-guided laser ablation: a cost comparison

OBJECTIVE

To compare the costs of CT-guided radiofrequency ablation (RFA) and MR-guided laser ablation (LA) for minimally invasive percutaneous treatment of osteoid osteoma.

MATERIALS AND METHODS

Between November 2005 and October 2011, 20 patients (14 males, 6 females, mean age 20.3±9.1 years) underwent CT-guided RFA and 24 patients (18 males, 6 females; mean age, 23.8±13.8 years) MR-guided LA (open 1.0 Tesla, Panorama HFO, Philips, Best, Netherlands) for osteoid osteoma diagnosed on the basis of clinical presentation and imaging findings. Prorated costs of equipment use (purchase, depreciation, and maintenance), staff costs, and expenditure for disposables were identified for CT-guided RFA and MR-guided LA procedures.

RESULTS

The average total costs per patient were EUR 1762 for CT-guided RFA and EUR 1417 for MR-guided LA. These were (RFA/LA) EUR 92/260 for equipment use, EUR 149/208 for staff, and EUR 870/300 for disposables.

CONCLUSION

MR-guided LA is less expensive than CT-guided RFA for minimally invasive percutaneous ablation of osteoid osteoma. The higher costs of RFA are primarily due to the higher price of the disposable RFA probes.

New insights into peripartum cardiomyopathy using cardiac magnetic resonance imaging

PURPOSE

The aim of this study was to evaluate a comprehensive cardiac magnetic resonance (MR) imaging approach in patients with peripartum cardiomyopathy (PPCM). The focus was on inflammatory myocardial changes.

MATERIALS AND METHODS

Retrospective analysis of 12 cardiac MR examinations was performed in 6 patients with PPCM. The protocol comprised cine sequences for the determination of chamber sizes and function. T 2-weighted sequences for determination of edema (T 2 ratio), T 1-weighted images for measurement of early gadolinium enhancement ratio (EGER), and late gadolinium enhancement (LGE) sequences were used for tissue characterization. 5 examinations were performed during the acute stage, and 7 examinations were performed during the course of the disease.

RESULTS

Initially, 3 of 5 patients presented with an elevated left ventricular end-diastolic volume (LVEDV); in one patient, the LVEDV was in the upper range. In 4 of 5 subjects, the left ventricular ejection fraction (LVEF) was decreased. The T 2 ratio and EGER values were initially elevated in all women. No LGE was detected in initial scans. In follow-up examinations, the LVEDV decreased and the LVEF increased in all patients. Tissue-characterizing parameters decreased to normal in all but 1 patient. 2 patients showing LGE did not present a favorable clinical course.

CONCLUSION

Myocardial inflammation was detected in the acute stage of PPCM, which was mostly transient. In our small group, patients showing LGE had a non-favorable clinical course. Future studies should include tissue-characterizing parameters, such as T 2 ratio and EGER. Thus, further insights into pathophysiology can be gained and therapeutic effects can be measured in a more extensive manner.

[Magnetic resonance cholangiographic (MRCP) features of ischemic-type biliary lesions (ITBL): a case-control study]

PURPOSE

To evaluate the spectrum of MR cholangiography (MRCP) features of ischemic-type biliary lesions (ITBL) after orthotopic liver transplantation (OLT).

MATERIALS AND METHODS

30 patients (16 m, 14 f) with an average age of 52 years (9 - 69 y) were examined in two 1.5 MR units using breath-hold 2D-SS-FSE-sequences and 3D-MRCP sequences. 20 of the 30 patients had an established ITBL, and the remaining 10 patients were post-OLT controls. MRCPs were evaluated independently by two experienced radiologists that were blinded to the clinical history as well as the results of other imaging modalities. All images were analyzed for the presence of 16 different pathological features. Differences between ITBL patients and controls were analyzed using the Mann-Whitney-U Test. Inter-rater variability was tested using the Cohen's Kappa test.

RESULTS

Abnormal findings of bile ducts were seen in all patients. The most common findings were (in percentage for reader 1 / 2) intrahepatic bile duct dilatation (95 % / 95 %) and extrahepatic bile duct stenoses (95 % / 85 %), followed by intrahepatic main duct stenoses (90 % / 95 %) and segmental duct stenoses (85 % / 85 %). Differences between ITBL patients and controls were significant for most of the analyzed features (Mann-Whitney-U test, p < 0.05). For 12 of 16 features, there was substantial or almost perfect agreement (κ = 0.61 - 1.00), for 2 of 16 features moderate agreement (κ = 0.41- 0.60) and for 2 of 16 features fair agreement (κ < 0.40).

CONCLUSION

In patients with ITBL, MR cholangiography reveals characteristic features that may allow differentiation from other biliary complications after liver transplantation.

[Targeted methods for measuring patient satisfaction in a radiological center]

PURPOSE

To investigate two event-oriented methods for evaluating patient satisfaction with radiological services like outpatient computed tomography (CT) examinations.

MATERIALS AND METHODS

159 patients (55% men, 45% women) were asked to complete a questionnaire to provide information about their satisfaction with their examination. At first, patients were asked to spontaneously recall notably positive and negative aspects (so-called "critical incidents", critical incident technique = CIT) of the examination. Subsequently a flow chart containing all single steps of the examination procedure was shown to all patients. They were asked to point out the positive and negative aspects they perceived at each step (so-called sequential incident technique = SIT).

RESULTS

The CIT-based part of the questionnaire yielded 356 comments (183 positive and 173 negative), which were assigned to one of four categories: interaction of staff with patient, procedure and organization, CT examination, and overall setting of the examination. Significantly more detailed comments regarding individual aspects of the CT examination were elicited in the second part of the survey, which was based on the SIT. There were 1413 statements with a significantly higher number of positive comments (n = 939, 66%) versus negative comments (n = 474, 34%; p < 0.001).

CONCLUSION

The critical and sequential incident techniques are suitable to measure the subjective satisfaction with the delivery of radiological services such as CT examinations. Positive comments confirm the adequacy of the existing procedures, while negative comments provide direct information about how service quality can be improved.

Diffusion-weighted imaging (DWI) in MR mammography (MRM): clinical comparison of echo planar imaging (EPI) and half-Fourier single-shot turbo spin echo (HASTE) diffusion techniques

Diffusion-weighted imaging (DWI) techniques have shown potential to differentiate between benign and malignant neoplasms. However, the diagnostic significance of using DWI under routine conditions remains unclear. This study investigated the use of echo planar imaging (EPI) and half-Fourier acquired single-shot turbo spin echo (HASTE)-DWI with respect to the three parameters: lesion visibility, apparent diffusion coefficient (ADC) measurements, and size estimation. Following MRM (1.5 T), EPI- and HASTE-DWI were applied in 65 patients. Lesion visibility on DWI was compared with lesion visibility on subtracted contrast-enhanced T1w images (CE-T1w). Statistical tests were applied to diameter, visibility, and ADC value measurements. Seventy-four lesions were identified. ADC value measurements did not differ significantly between the two DWI sequences. The sensitivity and specificity of routine diagnostics (97.4% and 85.7%) were superior to EPI-DWI (87.2% and 82.9%) and HASTE-DWI (76.9% and 88.6%). Selecting only nonmass lesions, DWI did not prove to be of diagnostic value. Lesion demarcation by DWI was significantly lower compared with that by CE-T1w, with EPI-DWI showing the better performance (p < 0.001). No significant differences were found for size measurements between CE-T1w and DWI. Although clearly inferior compared with CE-T1w imaging, both DWI techniques are applicable for lesion assessment and size measurements.

[Clinical value of computer-assisted analysis in MR mammography. A comparison between two systems and three observers with different levels of experience]

PURPOSE

The value of computer-assisted detection (CAD) used in magnetic resonance (MR) mammography in a clinical setting is currently a subject of controversy. This study evaluated the extent to which color-coded CAD systems aid radiologists with different levels of experience in their reading of MR mammographies.

MATERIALS AND METHODS

In this prospective study, 48 patients with a total of 88 lesions (43 malignant, 45 benign) were included. All examinations were performed on a 1.5 Tesla MR scanner with intravenous application of 0.1 mmol gadopentetate dimeglumine/kg body weight. Three readers independently analyzed the images without knowledge of the clinical data; radiologists 1 and 2 were much more experienced in the interpretation of MR mammographies than radiologist 3. Initially, the observers visually categorized the lesions as benign or malignant following classification of BI-RADS (Breast Imaging Reporting and Data System). The readers also scored their own confidence level using a dichotome score (1: unsure vs. 2: sure) according to the BI-RADS classification. The images were then analyzed in a blinded manner with two technically different CAD systems: the full-time point (FTP) method (Cadsciences; White Plains, NY, USA) and the Dynacad version 1.1 (Invivo; Pewaukee, WI, USA).

RESULTS

After CAD, all three readers classified more malignant lesions as BI-RADS 4 or 5 (suspicious or highly suggestive of malignancy). However, this increase in sensitivity revealed only statistical significance for observer 3 (p < 0.05). After CAD, the two experienced readers categorized about the same quantity of benign lesions correctly as BI-RADS 2. Observer 3 classified less benign lesions as BI-RADS 2 after both CAD analyses; i. e. the specificity decreased. The subjective confidence of all observers increased after analysis with Dynacad. Observer 3 also reported to be more confident after the FTP method.

CONCLUSION

Computer-assisted detection can be a useful additional diagnostic tool for the radiologist in the interpretation of MR mammographies, but does not have the potential to replace the professional experience of a radiologist.

Effects of long-term immobilisation on cortical bone mass after traumatic amputation of the phalanges estimated by digital X-ray radiogrammetry

Osteopenia of the cortical and trabecular bone partition is a common finding after immobilisation. Digital X-ray radiogrammetry (DXR) seems to quantify cortical demineralisation caused by circular saw amputation already few days after accident.

INTRODUCTION

The study analyses the extent of demineralisation caused by immobilisation in patients with digital amputation after a circular saw injury, and elucidates the period of time which discloses a significant deprivation of bone mineral density estimated at the metacarpalia II-IV using DXR.

METHODS

Twenty-eight patients with digital amputations underwent measurements of bone mineral density, cortical thickness, bone width and metacarpal index using DXR-technology in a follow-up up to 902 days.

RESULTS

The data showed a significant decline of bone mineral density (-10.47%), the metacarpal index (-4.38%), the bone width (-12.06%) and the cortical thickness (-7.04%) after trauma-related amputation. The cortical demineralisation of the metacarpals could already be revealed in two patients after the second day, according to the amputation of phalanges (-3.65%).

CONCLUSIONS

The inhibition of the periosteal bone formation detected by DXR-technique seems to be a specific finding caused by amputation, which thus differs from normal age-related (i.e., endosteal) bone loss and from demineralisation following acute immobilisation (i.e., trabecular osteopenia).