Tobias Krauss

Pre-procedural assessment of aortic annulus dimensions for transcatheter aortic valve replacement: comparison of a non-contrast 3D MRA protocol with contrast-enhanced cardiac dual-source CT angiography

AIMS To evaluate the feasibility of a non-contrast three-dimensional (3D)-FLASH magnetic resonance angiography (MRA) protocol for pre-procedural aortic annulus assessment for transcatheter aortic valve replacement (TAVR) in comparison with cardiac dual-source computed tomography angiography (CTA). METHODS AND RESULTS In this prospective study, 69 of 104 consecutive patients (mean age 81.8 ± 5.4 years, 37.7% arrhythmic) with severe aortic stenosis who had undergone pre-TAVR cardiac CTA received a respiratory and ECG-triggered, non-contrast 3D-FLASH MRA at 3 T. Annular area measurements were obtained at mid-diastole for both modalities whereas maximum systolic area was assessed by CTA only. Systolic MRA dimensions were modelled, by adding the relative difference of systolic and diastolic CTA area dimensions as a corrective factor. Hypothetical prosthesis sizing was performed based on systolic CTA, diastolic, and modelled systolic MRA area measurements. MR image quality and degree of annular calcifications were evaluated using 4-point-grading scales. The mean acquisition time was 14 ± 4.2 min. The mean image quality was 3.1 ± 0.9 with only two examinations rated non-diagnostic. The mean degree of calcifications was equal. As assessed by Bland-Altman analysis, there was no relevant systematic difference between area measurements for modelled systolic MRA and systolic CTA [the mean difference -3.1 mm(2) (limits of agreement -44.4 mm(2); 38.2 mm(2))]. Agreement for hypothetical prosthesis sizing was found in 63 of 67 (94%) patients for systolic CTA and modelled systolic MRA. CONCLUSION The employed non-contrast 3D-FLASH MRA protocol allows for reliable assessment of aortic annulus dimensions and calcifications even in the presence of arrhythmias in an all-comers pre-TAVR population. Implementation of this technique appears legitimate in patients at an increased risk for contrast-induced nephropathy.

Characterization of endolymphatic sac tumors and von Hippel–Lindau disease in the International Endolymphatic Sac Tumor Registry

Endolymphatic sac tumors (ELSTs) are, with a prevalence of up to 16%, a component of von Hippel–Lindau (VHL) disease. Data from international registries regarding heritable fraction and characteristics, germline VHL mutation frequency, and prevalence are lacking.

In vivo contact force measurements and correlation with left atrial anatomy during catheter ablation of atrial fibrillation

AIMS Lesion formation during catheter ablation crucially depends on catheter-tissue contact. We sought to evaluate the impact of anatomical characteristics of the left atrium (LA) and the pulmonary veins (PVs) on contact force (CF) measurements. METHODS AND RESULTS An anatomical map of the LA was obtained in 25 patients prior to catheter ablation of atrial fibrillation. Contact force (operator blinded) and local bipolar electrogram amplitudes (EGM) were measured in eight pre-defined segments around the PVs. After unblinding, points with low CF (≤5 g) were corrected to CF >5 g, and the distance between points was measured. In a pre-procedural computed tomography of the heart, LA volume as well as sizes and circumferences of the PV ostia were measured and correlated to CF measurements. Four hundred and twenty-six points in eight pre-defined LA locations were assessed. Low CF (<5 g) was found in 25.0% (43.5%) of points superior, 33.3% (66.7%) anterior, 32.1% (44.4%) inferior, and 15.5% (15.9%) posterior to the right (left) PVs. The mean distance after correction was 5.8 ± 3.4 mm. Local bipolar electrogram amplitudes between low- and high-CF points did not differ (1.21 ± 1.54 vs. 1.13 ± 1.3 mV, P = ns). The mean CF at the left PVs was significantly lower than at the right PVs (7.91 ± 3.74 vs. 13.95 ± 6.34 g, P < 0.001), with the lowest CF anterior to the left PVs (5.2 ± 3.6 g). Contact force measurements did not correlate to LA volume, size, and circumference of the PVs. CONCLUSION Contact force during LA mapping significantly differs according to the location within the LA. These differences are independent of LA volume and anatomy of the PV ostia.

Diagnostic performance and reproducibility of T2w based and diffusion weighted imaging (DWI) based PI-RADSv2 lexicon descriptors for prostate MRI

PURPOSE To examine the diagnostic performance of PI-RADSv2 T2w and diffusion weighted imaging (DWI) based lexicon descriptors, inter-observer agreement for descriptor assignment and diagnostic accuracy of the PI-RADSv2 assessment categories for multiparametric prostate MRI. MATERIALS AND METHODS 176 lesions in 79 consecutive patients are analyzed, lesions are histopathologically verified by MRI-ultrasound fusion biopsy. All lesions are rated according to the PI-RADSv2 lexicon, descriptors for T2w and DWI sequences and resulting assessment categories are assigned by two independent blinded radiologists. We perform receiver-operating-characteristic analysis using the assessment categories. To analyze inter-observer agreement, we calculate weighted kappa values for assessment category assignment and unweighted kappa values for descriptor assignment. RESULTS PI-RADSv2 assessment categories yield an area under the curve of 0.76/0.74 (radiologist 1/radiologist 2), P >0.05. Weighted kappa for agreement is 0.601 in the peripheral zone and 0.580 in the transition zone. We detect a difference in the cancer rate for PI-RADSv2 category 3 between peripheral zone (32%) and transition zone (12%), P <0.05. We obtain moderate agreement at most for descriptor assignment with kappa values ranging from 0.082 (T2w shape in the transition zone) to 0.407 (T2w signal intensity in the peripheral zone) and 0.493 (ADC pattern in the peripheral zone). Our analysis corroborates typical descriptors for benign/malignant lesions, but also reveals insights into potential pitfalls - T2w wedge shaped lesions in the peripheral zone have a considerable cancer rate, despite being labelled category 2 in the lexicon. CONCLUSION Agreement for descriptor assignment in the PI-RADSv2 lexicon is at most moderate in our study. Typical descriptors for benign and malignant lesions are validated, whereas the discriminatory power of some descriptors is challenged. The difference in the cancer rate for PI-RADSv2 category 3 between peripheral zone and transition zone should be considered when management recommendations are linked to assessment categories in the future.

PET/CT and MRI directed extended salvage radiotherapy in recurrent prostate cancer with lymph node metastases

PURPOSE PET/CT directed extended salvage radiotherapy (esRT) of involved lymph-node (LN) regions may be a salvage strategy for patients with nodal recurrent prostate cancer (PCa) after primary therapy or after previous prostate fossa salvage RT. The aim of the study was to determine the time until prostate-specific antigen (PSA) progression, pattern of failure and toxicity after esRT. MATERIAL AND METHODS 25 patients with nodal or nodal+local recurrent PCa confirmed by Choline-PET/CT and Magnetic Resonance Imaging (MRI) were treated with esRT at the sites of recurrence. Acute and late toxicity was recorded. In case of subsequent PSA progression, imaging was performed to confirm next relapse. Mean follow-up was 2.9 years. RESULTS According to Choline-PET/CT and MRI findings, 84% (21/25) of esRT were treatment of pelvic only, 12% (3/25) of retroperitoneal only and 4% (1/25) of both pelvic and retroperitoneal regions. 40% (10/25) received concomitant irradiation of the prostatic fossa (after primary radical prostatectomy). Median time to PSA progression of the whole cohort was 19.6 months. Median time to PSA progression for patients with 1-2 PET-positive LN (n=15) was 34.9 months versus median 12.7 months for patients with PET-positive LN≥3 (n=10), p-value: 0.0476. Acute and late toxicity was mild to moderate, no grade-3 adverse events were observed. CONCLUSION PET/CT and MRI directed esRT of nodal recurrent PCa with or without local recurrence is feasible with low acute and late toxicity. Patients with only one or two PET-positive LN treated by esRT achieved prolonged complete biochemical remission.

Preventive medicine for von Hippel-Lindau disease-associated pancreatic neuroendocrine tumors.

Pancreatic neuroendocrine tumors (PanNETs) are rare in von Hippel-Lindau disease (VHL) but cause serious morbidity and mortality. Management guidelines for VHL-PanNETs continue to be based on limited evidence, and survival data to guide surgical management are lacking. We established the European-American-Asian-VHL-PanNET-Registry to assess data for risks for metastases, survival and long-term outcomes to provide best management recommendations. Of 2330 VHL patients, 273 had a total of 484 PanNETs. Median age at diagnosis of PanNET was 35 years (range 10-75). Fifty-five (20%) patients had metastatic PanNETs. Metastatic PanNETs were significantly larger (median size 5 vs 2 cm; P < 0.001) and tumor volume doubling time (TVDT) was faster (22 vs 126 months; P = 0.001). All metastatic tumors were ≥2.8 cm. Codons 161 and 167 were hotspots for VHL germline mutations with enhanced risk for metastatic PanNETs. Multivariate prediction modeling disclosed maximum tumor diameter and TVDT as significant predictors for metastatic disease (positive and negative predictive values of 51% and 100% for diameter cut-off ≥2.8 cm, 44% and 91% for TVDT cut-off of ≤24 months). In 117 of 273 patients, PanNETs >1.5 cm in diameter were operated. Ten-year survival was significantly longer in operated vs non-operated patients, in particular for PanNETs <2.8 cm vs ≥2.8 cm (94% vs 85% by 10 years; P = 0.020; 80% vs 50% at 10 years; P = 0.030). This study demonstrates that patients with PanNET approaching the cut-off diameter of 2.8 cm should be operated. Mutations in exon 3, especially of codons 161/167 are at enhanced risk for metastatic PanNETs. Survival is significantly longer in operated non-metastatic VHL-PanNETs.

Genetics Informs Precision Practice in the Diagnosis and Management of Pheochromocytoma

Although the authors of the present review have contributed to genetic discoveries in the field of pheochromocytoma research, we can legitimately ask whether these advances have led to improvements in the diagnosis and management of patients with pheochromocytoma. The answer to this question is an emphatic Yes! In the field of molecular genetics, the well-established axiom that familial (genetic) pheochromocytoma represents 10% of all cases has been overturned, with >35% of cases now attributable to germline disease-causing mutations. Furthermore, genetic pheochromocytoma can now be grouped into five different clinical presentation types in the context of the ten known susceptibility genes for pheochromocytoma-associated syndromes. We now have the tools to diagnose patients with genetic pheochromocytoma, identify germline mutation carriers and to offer gene-informed medical management including enhanced surveillance and prevention. Clinically, we now treat an entire family of tumors of the paraganglia, with the exact phenotype varying by specific gene. In terms of detection and classification, simultaneous advances in biochemical detection and imaging localization have taken place, and the histopathology of the paraganglioma tumor family has been revised by immunohistochemical-genetic classification by gene-specific antibody immunohistochemistry. Treatment options have also been substantially enriched by the application of minimally invasive and adrenal-sparing surgery. Finally and most importantly, it is now widely recognized that patients with genetic pheochromocytoma/paraganglioma syndromes should be treated in specialized centers dedicated to the diagnosis, treatment and surveillance of this rare neoplasm.

Peripheral zone lesions of intermediary risk in multiparametric prostate MRI: Frequency and validation of the PI-RADSv2 risk stratification algorithm based on focal contrast enhancement

PURPOSE To validate the risk stratification algorithm of the Prostate Imaging Reporting and Data System (PI-RADSv2) for intermediary risk lesions (PI-RADSv2 category 3) in the peripheral zone based on focal contrast enhancement and to compare cancer rates in category 3, upgraded category 4 and category 4 based on markedly low ADC value. MATERIALS AND METHODS We retrospectively analyze 172 consecutive patients undergoing prostate MRI with 315 histopathologically verified lesions. We select all lesions either assigned category 3 or category 4 in the peripheral zone for further analysis. We compare cancer rates with the two-sided chi-squared test. To determine inter-observer agreement about contrast enhancement two blinded radiologists evaluate the subset of category 3 lesions based on the diffusion weighted sequence. RESULTS The frequency of peripheral PI-RADS 3, upgraded PI-RADS 4 and PI-RADS 4 lesions based on markedly low ADC value is 10.8%, 10.8% and 20.3%, respectively. Cancer rates (significant cancer only) in these subgroups are 8.8% (3/34), 23.5% (8/34) and 40.6% (26/64), P < 0.01. Inter-observer agreement is moderate for evaluation of contrast enhancement with kappa values between 0.46 and 0.5. CONCLUSION We demonstrate a trend of increasing cancer rate from PI-RADSv2 category 3 to upgraded category 4 to category 4 based on markedly low ADC value. Peripheral lesions of intermediary risk in the diffusion weighted sequence account for 21.6% of all prostate lesions encountered. Since it is likely that patient management recommendations will be linked to assessment categories in future versions of PI-RADS, cancer rates in upgraded category 4 and category 4 based on markedly low ADC values should be in a similar range. We conclude that in future studies of PI-RADSv2 upgraded category 4 and category 4 based on markedly low ADC value should be reported separately to generate a database for meta-analysis of cancer rates.

Post-TAVI Follow-Up with MDCT of the Valve Prosthesis: Technical Application, Regular Findings and Typical Local Post-Interventional Complications

BACKGROUND  Transcatheter aortic valve implantation (TAVI) has evolved into an alternative procedure to surgical valve replacement for high-risk patients with aortic valve stenosis. Despite technical innovations, there is still a risk of complications during and after the intervention. After a TAVI procedure, ECG-gated multidetector computed tomography (MDCT) plays an important role in the early diagnosis of local complications. In this article, we explain for the first time how the technical acquisition of MDCT in the region of the aortic root is performed as post-interventional control of the TAVI prosthesis. In the second part normal post-interventional findings of different prosthetic valves as well as classic and uncommon complications in the implant area will be illustrated in several case studies. METHODS  In this review the current literature from PubMed about ECG-gated MDCT after TAVI is summarized and structured. It is supplemented by several case studies from our institution. RESULTS AND CONCLUSION  Using retrospectively ECG-gated MDCT, an aortic valve prosthesis after TAVI can be visualized with high spatial resolution in several phases of the cardiac cycle. Images of the implanted aortic valve at all time points of the cardiac cycle enable a functional analysis of prosthetic leaflets similar to echocardiography. MDCT is superior to transthoracic echocardiography with respect to the direct detection of prosthetic leaflet thrombosis. The position of the device in relation to the coronary ostia and correct unfolding of the stent frame need to be evaluated. There are different types of stents carrying the valve leaflets with distinct ideal positions. Any stent should cover the left ventricular outflow tract (LVOT) along its whole circumference. Life-threatening complications in the implant area, such as annulus rupture, can be diagnosed reliably with CT. KEY POINTS   · ECG-gated multidetector CT (MDCT) after transcatheter aortic valve implantation (TAVI) can provide early detection of postinterventional complications of the prosthetic valve and the aortic root.. · MDCT is superior to echocardiography with respect to the direct detection of prosthetic leaflet thrombosis.. · MDCT can also reveal hypokinesia of the thrombotic valve leaflets.. · Correct position of the device und unfolding of the stent frame differ according to the type of prosthesis.. · The integrity of the native aortic root should be carefully assessed.. CITATION FORMAT · Soschynski M, Capilli F, Ruile P et al. Post-TAVI Follow-Up with MDCT of the Valve Prosthesis: Technical Application, Regular Findings and Typical Local Post-Interventional Complications. Fortschr Röntgenstr 2018; 190: 521 - 530.