Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data.

INTRODUCTION: To increase precision of radiation treatment (RT) delivery in prostate cancer, MRI-based RT as well as the use of fiducials like gold markers (GMs) have shown promising results. Their combined use is currently under investigation in clinical trials. Here, we aimed to evaluate a workflow of image registration based on GMs between CT and MRI as well as weekly MRI-MRI adaption based on T2 TSE sequence. MATERIAL AND METHODS: A gel-phantom with two inserted GMs was scanned with CT and three different MR-scanners of 1.5 and 3 T (T2 TSE and T1 VIBE-Dixon, isotropic, voxel size 2 × 2 × 2 mm). After image fusion, deviations for fiducial and gel match were measured and artifacts were evaluated. Additionally, CT-MRI-match deviations and MRI-MRI-match deviations of 10 Patients from the M-basePro study using GMs were assessed. RESULTS: GMs were visible in all imaging modalities. The outer gel contours were matched with <1 mm deviation, contour volumes varied between 0 and 1%. The deviations of the GMs were less than 2 mm in any direction of MRI/CT. Shifts of peripherally or centrally located GMs were randomly distributed. The average MRI-CT-match precision of 10 patients with GMs was 1.9 mm (range 1.1-3.1 mm). CONCLUSIONS: Match inaccuracies for GMs between reference CT and voxel-isotropic T2-TSE sequences are small. Spatial deviations of CT- and MR-contoured fiducials were less than 2 mm, i.e., below SLT of the applied modalities. In patients, the average CT-MRI-match precision for GMs was 1.9 mm supporting their use in MR-guided high precision RT.

[TKI 2.0 - changes in the medical treatment of renal cell carcinoma]. / TKI 2.0 ­ Wandel in der medikamentösen Therapie des Nierenzellkarzinoms.

Only for renal cell carcinoma (RCC) in a local stage curative treatment option by surgical resection exists. For metastatic disease the 5­year survival rate decreases radically. A factor that contributes to this is the low sensibility to radiation and chemotherapeutics. Since the approval of the tyrosine kinase inhibitors in 2006 effective drugs for the treatment of mRCC is available. The specific inhibition of the vascular-endothelial-growth (VEGF)-receptor and the "mammalian Target of Rapamycin" (mTOR) leads to a prolongation of the progression-free survival as well as the overall survival rate. For a long time, the current target therapy with TKI appeared to be exhausted, but since recently research has gone a step further. Thus, Cabozantinib and Lenvatinib in the combination with Everolimus have been approved for second-line therapy in mRCC. For the first time a clinical study demonstrated positive results for an adjuvant treatment with sunitinib in patients with a high-risk RCC. Furthermore, in april 2016 the immune checkpoint inhibitor Nivolumab was approved for second-line therapy in mRCC in Germany. The following report examines briefly the current therapeutic recommendations, new findings and drug approvals and ongoing clinical trials.

Experimental characterization of the biaxial mechanical properties of porcine gastric tissue.

Health problems related to the stomach are among the most important sources of morbidity in industrialized countries. There is evidence that mechanics may play an important role in various such pathologies. However, so far experimental data characterizing the mechanical properties of gastric tissue remain scarce, which significantly limits our understanding of the mechanics of the stomach. To help close this gap, we performed biaxial mechanical tests of porcine gastric tissue patches. Our experiments reveal a considerable anisotropy and different mechanical properties in the three major regions of the stomach (fundus, corpus, antrum). Moreover, they demonstrate that the mechanical properties of the gastric wall and the physiological function of the different regions of the stomach are closely related. This finding suggests that further examination of the mechanics of the gastric wall may indeed be a promising avenue of research towards a better understanding of the organic causes of frequent health problems related to the stomach.

Diagnostic accuracy of contemporary multidetector computed tomography (MDCT) for the detection of lumbar disc herniation.

OBJECTIVES: To evaluate the diagnostic accuracy of multidetector CT (MDCT) for detection of lumbar disc herniation with MRI as standard of reference. METHODS: Patients with low back pain underwent indicated MDCT (128-row MDCT, helical pitch), 60 patients with iterative reconstruction (IR) and 67 patients with filtered back projection (FBP). Lumbar spine MRI (1.5 T) was performed within 1 month. Signal-to-noise ratios (SNR) of cerebrospinal fluid (CSF), annulus fibrosus (AF) and the spinal cord (SC) were determined for all modalities. Two readers independently rated image quality (IQ), diagnostic confidence and accuracy in the diagnosis of lumbar disc herniation using MRI as standard of reference. Inter-reader correlation was assessed with weighted κ. RESULTS: Sensitivity, specificity, precision and accuracy of MDCT for disc protrusion were 98.8%, 96.5%, 97.1%, 97.8% (disc level), 97.7%, 92.9%, 98.6%, 96.9% (patient level). SNR of IR was significantly higher than FBP. IQ was significantly better in IR owing to visually reduced noise and improved delineation of the discs. κ (>0.90) was excellent for both algorithms. CONCLUSION: MDCT of the lumbar spine yields high diagnostic accuracy for detection of lumbar disc herniation. IR improves image quality so that the provided diagnostic accuracy is principally equivalent to MRI. KEY POINTS: • MDCT is an accurate alternative to MRI in disc herniation diagnosis. • By IR enhanced image quality improves MDCT diagnostic confidence similar to MRI. • Advances in CT technology contribute to improved diagnostic performance in lumbar spine imaging.

First report of robot-assisted transperineal fusion versus off-target biopsy in patients undergoing repeat prostate biopsy.

PURPOSE: To clarify the value of targeted versus off-target biopsies in men with a suspicion of prostate cancer (PC) and a visible lesion in multi-parametric magnetic resonance imaging (mpMRI) using transperineal robot-assisted biopsy. METHODS: Fifty-five consecutive men with one non-palpable suspicious lesion in mpMRI after negative 12-core transrectal ultrasound-guided biopsy were enrolled in 2014-2015. Lesions were scored using the Prostate Imaging Reporting and Data System. A robot-assisted system was utilized to collect four robot-assisted targeted transperineal biopsy cores (RA-TB) within the lesion using mpMRI-TRUS elastic fusion. Untargeted transperineal 14-core biopsy was performed only outside the lesion (RA-UB). Histological grade was compared in biopsies and available prostatectomy specimens. RESULTS: Overall, 34 of 55 patients (62%) were diagnosed with PC based on biopsy. 85% of cancers were clinically significant PC (csPC) defined as GS ≥ 7. 85% of biopsy-proven cancers were detected with RA-TB alone. RA-UB identified only one additional patient with csPC and lead to upgrading in five biopsy cases (14.7%). Pathological evaluation of 14 prostatectomy specimens showed upgrading in 2 patients (14.3%), while all other patients were correctly classified by RA-TB without need of additional RA-UB. Mean procedure duration was 43 (±6) min, and only minor complications according to Clavien-Dindo were recorded during 30-day follow-up. CONCLUSIONS: This is the first report of transperineal robot-assisted elastic mpMRI-TRUS fusion biopsy. RA-TB of positive MR lesions enabled reliable detection of csPC, while RA-UB in MRI-negative regions is of minor importance.

Prostate cancer gene 3 (PCA3) is of additional predictive value in patients with PI-RADS grade III (intermediate) lesions in the MR-guided re-biopsy setting for prostate cancer.

PURPOSE: Multiparametric magnetic resonance imaging (mpMRI) improves diagnostic accuracy in re-biopsies of men with prostate cancer (PC) suspicion, but predictive value is limited despite the use of the new Prostate Imaging Reporting and Data System (PI-RADS). Prognostic value of the PC-specific biomarker prostate cancer gene 3 (PCA3) added to the PI-RADS score was evaluated. METHODS: The study was a retrospective analysis of the institutional database for men with MR-guided biopsy (MR-GB) for suspicious lesion in mpMRI and who had an additional pre-MR-GB PCA3 testing for ongoing PC suspicion. All men had ≥ 1 negative ultrasound GB. Lesions were retrospectively scored by PI-RADS in three MRI sequences (T2w, DCE, and DWI). PCA3 was analyzed with cutoffs of 25 and 35. The prognostic value of mpMRI and PCA3 and the additional value of both were explored. RESULTS: Tumor detection rate (49 men, mean PSA 10 ng/ml, lesion size 40 mm(2)) was 45 % (22/49 patients). In the subgroup of PI-RADS IV°, 17/17 patients had PC; in PI-RADS III° (intermediate) 5/15 had PC, and all 5 had a PCA3 > 35. PCA3 > 35 had no additional prognostic value in the whole cohort. Out of the 10/15 PC negative patients (PI-RADS III°), PCA3 was < 35 in 6. The inclusion of PCA3 value in PI-RADS III° patients improved predictive accuracy to 91.8 %. CONCLUSION: MpMRI and subsequent grading to PI-RADS significantly improves PC detection in the re-biopsy setting. The diagnostic uncertainty in the PI-RADS intermediate group can be ameliorated by the addition of PCA3 cutoff of 35 to avoid potential unnecessary biopsies.

[Functional magnetic resonance imaging of the kidneys]. / Funktionelle Magnetresonanztomographie der Nieren.

Interest in functional renal magnetic resonance imaging (MRI) has significantly increased in recent years. This review article provides an overview of the most important functional imaging techniques and their potential clinical applications for assessment of native and transplanted kidneys, with special emphasis on the clarification of renal tumors.

[Technique of Autologous Chondrocyte Implantation for Severe Radiocarpal Arthrosis: Status Quo after 24 Months]. / Technik der autologen Chondrozytenimplantation bei ausgeprägter Radiokarpalarthrose: Status quo nach 24 Monaten.

We illustrate the operative technique of autologous chondrocyte implantation (ACI) to restore a 4° cartilage damage of the radius surface in the case of a 22-year-old patient, and report on the clinical and radiological results at 6 and 24 months postoperatively.

[Diagnostic accuracy of dual energy CT angiography in patients with diabetes mellitus]. / Diagnostische Genauigkeit der Dual-energy-CT-Angiographie bei Patienten mit Diabetes mellitus.

OBJECTIVES: Peripheral arterial disease (PAD) represents a major and highly prevalent complication in patients with diabetes mellitus. The diagnostic, non-invasive work-up by computed tomography angiography (CTA) is limited in the presence of extensive calcification. The aim of the study was to determine the diagnostic accuracy of dual energy CTA (DE-CTA) for the detection and characterization of PAD in patients with diabetes mellitus. MATERIAL AND METHODS: In this study 30 diabetic patients with suspected or known PAD were retrospectively included in the analysis. All subjects underwent DE-CTA (Somatom Definition Flash, Siemens Healthcare, Erlangen, Germany) prior to invasive angiography, which served as the reference standard. Blinded analysis included assessment of the presence and degree of peripheral stenosis on curved multiplanar reformatting (MPR) and maximum intensity projections (MIP). Conventional measures of diagnostic accuracy were derived. RESULTS: Among the 30 subjects included in the analysis (83% male, mean age 70.0 ± 10.5 years, 83% diabetes type 2), the prevalence of critical stenosis in 331 evaluated vessel segments was high (30%). Dual energy CT identified critical stenoses with a high sensitivity and good specificity using curved MPR (100% and 93.1%, respectively) and MIP images (99% and 91.8%, respectively). In stratified analysis, the diagnostic accuracy was higher for stenosis pertaining to the pelvic and thigh vessels as compared with the lower extremities (curved MPR accuracy 97.1% vs. 99.2 vs. 90.9%; respectively, p < 0.001). CONCLUSION: The use of DE-CTA allows reliable detection and characterization of peripheral arterial stenosis in patients with diabetes mellitus with higher accuracy in vessels in the pelvic and thigh regions compared with the vessels in the lower legs.

Topographic deformation patterns of knee cartilage after exercises with high knee flexion: an in vivo 3D MRI study using voxel-based analysis at 3T.

OBJECTIVES: To implement a novel voxel-based technique to identify statistically significant local cartilage deformation and analyze in-vivo topographic knee cartilage deformation patterns using a voxel-based thickness map approach for high-flexion postures. METHODS: Sagittal 3T 3D-T1w-FLASH-WE-sequences of 10 healthy knees were acquired before and immediately after loading (kneeling/squatting/heel sitting/knee bends). After cartilage segmentation, 3D-reconstruction and 3D-registration, colour-coded deformation maps were generated by voxel-based subtraction of loaded from unloaded datasets to visualize cartilage thickness changes in all knee compartments. RESULTS: Compression areas were found bifocal at the peripheral medial/caudolateral patella, both posterior femoral condyles and both anterior/central tibiae. Local cartilage thickening were found adjacent to the compression areas. Significant local strain ranged from +13 to -15 %. Changes were most pronounced after squatting, least after knee bends. Shape and location of deformation areas varied slightly with the loading paradigm, but followed a similar pattern consistent between different individuals. CONCLUSIONS: Voxel-based deformation maps identify individual in-vivo load-specific and posture-associated strain distribution in the articular cartilage. The data facilitate understanding individual knee loading properties and contribute to improve biomechanical 3 models. They lay a base to investigate the relationship between cartilage degeneration patterns in common osteoarthritis and areas at risk of cartilage wear due to mechanical loading in work-related activities. KEY POINTS: • 3D MRI helps differentiate true knee-cartilage deformation from random measurement error • 3D MRI maps depict in vivo topographic distribution of cartilage deformation after loading • 3D MRI maps depict in vivo intensity of cartilage deformation after loading • Locating cartilage contact areas might aid differentiating common and work-related osteoarthritis.

Magnetic resonance imaging versus lymphoscintigraphy for the assessment of focal lymphatic transport disorders of the lower limb: first experiences.

PURPOSE: To compare the diagnostic accuracy of magnetic resonance imaging (MR-lymphangiography) and lymphoscintigraphy for assessment of focal lesions of the peripheral lymphatic system. Patients with focal lymphatic transport disorders might benefit from surgi-cal interventions. PATIENTS, METHODS: We examined by lymphoscintigraphy and MR-lymphangiography a total of 85 lower limbs in 46 consecutive patients (33 women; mean age 41 years; range 9-79 years) presenting with uni- or bilateral lymphedema. MR-lymphangiographies were obtained at isotropic sub-millimeter resolution with a 3.0 Tesla magnet after injection of gadolinium contrast medium. MR-lymphangiography was reviewed by radiologists, whereas lymphoscintigraphy was reviewed by nuclear medicine physicians. The images were examined for localization and distribution of any focal lesions of the lymphatic vessel system. Diagnostic accuracy of the MR-approach was calculated relative to the lymphoscintigraphy gold standard. RESULTS: There was substantial correlation of results by the two modalities (κ = 0.62). MR-lymphangiography had sensitivity of 68%, specificity of 91%, positive predictive value of 82%, and negative predictive value of 83%. CONCLUSIONS: Imaging findings of both lymphoscintigraphy and MR-lymphangiography showed good diagnostic accuracy. MR-lymphangiography proved more information about anatomic location of focal lesions of the lymphatic vessels, but use of MR-lymphangiography is currently constrained due to the requirement for off-label subcutaneous injection of gadolinium chelates. Consequently, and due to its superior sensitivity lymphoscintigraphy remains the most common imaging method to assess functional lymphatic disorders of the lower limb.

CT perfusion technique for assessment of early kidney allograft dysfunction: preliminary results.

OBJECTIVES: To assess the benefit of quantitative computed tomography (CT) perfusion for differentiating acute tubular necrosis (ATN) and acute rejection (AR) in kidney allografts. METHODS: Twenty-two patients with acute kidney allograft dysfunction caused by either AR (n = 6) or ATN (n = 16) were retrospectively included in the study. All patients initially underwent a multiphase CT angiography (CTA) protocol (12 phases, one phase every 3.5 s) covering the whole graft to exclude acute postoperative complications. Multiphase CT dataset and dedicated software were used to calculate renal blood flow. Renal biopsy or clinical course of disease served as the standard of reference. Mean effective radiation dose and mean amount of contrast media were calculated. RESULTS: Renal blood flow values were significantly lower (P = 0.001) in allografts undergoing AR (48.3 ± 21 ml/100 ml/min) compared with those with ATN (77.5 ± 21 ml/100 ml/min). No significant difference (P = 0.71) was observed regarding creatinine level with 5.65 ± 3.1 mg/dl in AR and 5.3 ± 1.9 mg/dl in ATN. The mean effective radiation dose of the CT perfusion protocol was 13.6 ± 5.2 mSv; the mean amount of contrast media applied was 34.5 ± 5.1 ml. All examinations were performed without complications. CONCLUSION: CT perfusion of kidney allografts may help to differentiate between ATN and rejection. KEY POINTS: • Quantitative CT perfusion of renal transplants is feasible. • CT perfusion could help to non-invasively differentiate AR from ATN. • CT perfusion might make some renal biopsies unnecessary.

[Modern imaging of kidney tumors]. / Moderne Bildgebung von Nierentumoren.

If a renal mass is suspected on clinical examination or ultrasound the finding has to be confirmed by cross-sectional imaging. Methods that are used include multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI). Also contrast-enhanced ultrasound has been successfully implemented in renal imaging and now plays a major role in the differentiation of benign from malignant renal masses. In expert hands it can be used to show very faint vascularization and subtle enhancement. The MDCT technique benefits from the recently introduced dual energy technology that allows superior characterization of renal masses in a single-phase examination, thereby greatly reducing radiation exposure. For young patients and persons allergic to iodine MRI should be used and it provides excellent soft tissue contrast and visualizes contrast enhancement kinetics in multiphase examinations.This article aims at giving a comprehensive overview of these different imaging modalities, their clinical indications and contraindications, as well as a description of imaging findings of various renal masses.

[MR lymphangiography for assessment of focal dermal backflow for presurgical work-up in patients with peripheral lymphoedema]. / Die MR-Lymphangiografie in der präoperativen Diagnostik des fokalen "dermal backflow" bei peripheren Lymphödemen.

BACKGROUND: MR lymphangiography might provide valuable morphological information in the diagnosis of peripheral lymphedema in addition to lymphoscintigraphy. Even patients with focal dermal backflow can benefit from surgical intervention. The purpose of this study was to assess the feasibility of MR-Lymphangiography for assessment of focal dermal backflow for pre-surgical work-up. PATIENTS/MATERIALS & METHODS: 50 patients with peripheral lymphedema were included in this study. Patients showing focal dermal backflow in MR-Lymphangiography were reviewed and analyzed separately. The MR findings were correlated to lymphoscintigraphy. Concordance of the 2 modalities regarding existence and distribution of dermal backflow were examined. Furthermore the feeding vessels of the dermal backflow were assessed and visualized. RESULTS: Dermal backflow was diagnosed with MR lymphangiography in 13 patients. Dermal backflow was confirmed by lymphoscintigraphy in 12 patients (92.3%). The feeding vessels of the dermal backflow configuration could be visualized in 9 patients (69.2%) and could be visualized with 3-dimensional reconstructions. The latter is not possible with lymphoscintigraphy. CONCLUSION: MR lymphangiography provides important supplementary diagnostic information in patients with peripheral lymphedema additional to lymphoscintigraphy. Particularly in patients with focal dermal backflow and intended surgery, MR lymphangiography holds high potential for pre-surgical work-up.

[Update on special surgical approaches in the therapy for lymphedemas]. / Die Vielfalt in der chirurgischen Therapie beim Lymphödem - was ist aktuell?

Despite recent medical progress primary and secondary lymphedemas still represent a therapeutic challenge and they often lead to a significant reduction in quality of life. Lymphedemas usually develop in the extremities, the male external genitals as well as the female breast as a consequence to the axial alignment of the lymphatic collectors. Early stages are characterized by an excess of lymph fluid increasing the volume of the affected part of the body whereas later stages represent an increasing amount of solid tissue. Thus therapeutic efforts can focus on the reduction of the surplus of liquid and/or solid components. Generally there are conservative and operative strategies. Conservative measures mainly focus on the improvement of fluid mobilization and drainage and comprise compression garments, manual lymphatic drainage, and apparative intermittent compression. Operative approaches comprise procedures for surgical tissue reduction (symptomatic/ablative approaches) and/or procedures with the intention of enhancing lymphatic transport (causal approaches). Surgical tissue reduction can be performed by open resection and/or liposuction. Traditional surgical causal techniques such as transposition of local flaps aim at leading lymph away from the congested region of the body. Modern microsurgical causal approaches contain methods of reconstruction of interrupted lymphatic pathways as well as techniques for the conduction of lymph into local veins. In this review we depict and discuss the features of the multiform spectrum of the surgical therapy of lymphedemas on the basis of literature as well as our own clinical and experimental experience.

Ultrasound image fusion - clinical implementation and potential benefits for monitoring of renal transplants.

PURPOSE: To evaluate the feasibility of US image fusion in the clinical routine and to discuss potential benefits for follow-up after renal transplantation. MATERIALS AND METHODS: 15 patients with a renal transplant were prospectively included in the study. For all of them, a previously performed CT- or MRI-scan covering the renal transplant was available. Each patient was investigated using ultrasound image fusion. Time needed for sucessful implementation of image fusion was registered. Subsequently, quality of image fusion was assessed by two experienced radiologists (10 and 5 years of experience) in consensus using a subjective 5 point rank scale (1 = best). RESULTS: Image fusion was successfully performed in all patients. Time needed for setup of image fusion varied from 45-120 sec (85 ± 5 sec). The score for quality of US image fusion was 1.9 ± 0.7. CONCLUSION: Assessment of renal transplants using US image fusion is feasible and provides several potential benefits for the follow-up of renal transplants.

Multimodality imaging using ultrasound image fusion in renal lesions.

OBJECTIVES: To assess the benefit of ultrasound (US) image fusion in the identifiability and assessment of the dignity of renal lesions. MATERIALS AND METHODS: 25 patients with 29 renal lesions were investigated using standard US and CEUS (contrast enhanced US) with image fusion (CT or MRI). Identifiability and assessment of dignity was evaluated using cross-sectional images and US separately as well as using both US-techniques with additional image fusion. The respective modality was rated by two experienced radiologists (10 and 5 years of experience) using a (subjective) 5 point rank scale (1 = best). RESULTS: Using CEUS, image fusion resulted in improved identifiability (score: 1.1 ± 0.4) and improved assessment of dignity (score 1.0 ± 0) of renal lesions than using cross sectional images (score 1.8 ± 1.2 and 3.8 ± 1.2 respectively) separately. CONCLUSION: Image fusion improved the identifiability and the assessment of the dignity of renal lesions compared to using the respective modalities separately.

FDG-PET-CT and whole-body MRI for triage in patients planned for radioembolisation therapy.

PURPOSE: The purpose was to evaluate the potential of FDG-PET-CT and whole-body MRI (WB-MRI) as diagnostic triage methods for patients planned for radioembolisation of metastatic liver disease. MATERIALS AND METHODS: 135 patients with multifocal liver metastases were evaluated for potential palliative therapy with radioembolisation using 90-Yttrium microspheres. All patients were examined consecutively with FDG-PET-CT and WB-MRI for exclusion of relevant extra-hepatic tumor manifestations. All patients underwent 99mTc-albumine angiography followed by scintigraphy to exclude significant hepato-pulmonary shunting. RESULTS: Out of the 135 patients included into the pre-therapeutic diagnostic algorithm, 56% were eligible and received radioembolisation, while 44% could not be treated. In 91% the exclusion criteria was diagnosis of significant extra-hepatic metastatic disease. In 85% exclusion diagnosis was made concordantly by both FDG-PET-CT and WB-MRI, in 9% diagnosis was provided by PET-CT, in 6% by WB-MRI alone. Patient-based sensitivity for detection of extra-hepatic disease was 94% for PET-CT and 91% for WB-MRI. False-positive diagnosis of extrahepatic disease leading to exclusion for radioembolisation therapy was made in 2% of patients, in one patient by PET-CT and in one patient by WB-MRI alone. Overall, specificity for inclusion of radioembolisation therapy by combining both modalities was 99%. In 9% of patients angiographic diagnosis made radioembolisation impossible, in 7% solely the angiographic findings were decisive. CONCLUSION: Both FDG-PET-CT and WB-MRI are efficient diagnostic triage methods for patients planned for radioembolisation of liver metastases. Overall, FDG-PET-CT shows a trend to higher diagnostic accuracy compared to WB-MRI and may be used as imaging method of choice as a standalone examination. In combination, both modalities exhibited high sensitivity for the diagnosis of extra-hepatic tumor manifestations and result in high specificity.