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Background: Previously, T2-relaxation time (T2 app ) and proton spin density (ρ) detected nerve injury in a small group of ATTRv amyloidosis. Here, we aim to quantify peripheral nerve impairment in a large cohort of symptomatic and asymptomatic ATTRv amyloidosis and correlate T2-relaxometry markers with clinical parameters and nerve conduction studies (NCS)., Methods: Eighty participants with pathologic variants of the transthyretin gene ( TTRv ) and 40 controls prospectively underwent magnetic resonance neurography. T2-relaxometry was performed, allowing to calculate tibial ρ, T2 app and cross-sectional-area (CSA). Detailed clinical examinations and NCS of tibial and peroneal nerves were performed., Results: Forty participants were classified as asymptomatic TTRv -carriers, 40 as symptomatic patients with polyneuropathy. ρ, T2 app and CSA were significantly higher in symptomatic ATTRv amyloidosis (484.2 ± 14.8 a.u.; 70.6 ± 1.8 ms; 25.7 ± 0.9 mm 2 ) versus TTRv- carriers (413.1 ± 9.4 a.u., p  < 0.0001; 62.3 ± 1.3 ms, p  = 0.0002; 19.0 ± 0.8 mm 2 , p  < 0.0001) and versus controls (362.6 ± 7.5 a.u., p  < 0.0001; 59.5 ± 1.0 ms, p  < 0.0001; 15.4 ± 0.5 mm 2 , p  < 0.0001). Only ρ and CSA differentiated TTRv- carriers from controls. ρ and CSA correlated with NCS in TTRv -carriers, while T2 app correlated with NCS in symptomatic ATTRv amyloidosis. Both ρ and T2 app correlated with clinical score., Conclusion: ρ and CSA can detect early nerve injury and correlate with electrophysiology in asymptomatic TTRv -carriers. T2 app increases only in symptomatic ATTRv amyloidosis in whom it correlates with clinical scores and electrophysiology. Our results suggest that T2-relaxometry can provide biomarkers for disease- and therapy-monitoring in the future.

Objectives: Multi spin echo (MSE) sequences are often used for obtaining T2-relaxometry data as they provide defined echo times (TEs). Due to their time-consuming acquisition, they are frequently replaced by turbo spin echo (TSE) sequences that in turn bear the risk of systematic errors when analyzing small structures or lesions. With this study, we aim to test whether T2-relaxometry data derived from either dual-echo TSE or 12-echo MSE sequences are equivalent for quantifying peripheral nerve lesions. Hereditary transthyretin (ATTRv) amyloidosis was chosen as a surrogate disease, as it allows the inclusion of both asymptomatic carriers of the underlying variant transthyretin gene (varTTR) and symptomatic ATTRv amyloidosis patients., Materials and Methods: Overall, 50 participants with genetically confirmed varTTR (20 clinically symptomatic ATTRv amyloidosis; 4 females, 16 males; mean age, 61.8 years; range, 33-76 years; and 30 asymptomatic varTTR-carriers; 18 females, 12 males; mean age, 43.1 years; range, 21-62 years), and 30 healthy volunteers (13 females, 17 males, mean age 41.3 years, range 22-73) were prospectively included and underwent magnetic resonance neurography at 3 T. T2-relaxometry was performed by acquiring an axial 2-dimensional dual-echo TSE sequence with spectral fat saturation (TE1/TE2, 12/73 milliseconds; TR, 5210 milliseconds; acquisition time, 7 minutes, 30 seconds), and an axial 2-dimensional MSE sequence with spectral fat saturation and with 12 different TE (TE1, 10 milliseconds to TE12, 120 milliseconds; ΔTE, 10 milliseconds; TR, 3000 milliseconds; acquisition time, 11 minutes, 23 seconds) at the right mid to lower thigh. Sciatic nerve regions of interest were manually drawn in ImageJ on 10 central slices per participant and sequence, and the apparent T2-relaxation time (T2app) and proton spin density (ρ) were calculated individually from TSE and MSE relaxometry data., Results: Linear regression showed that T2app values obtained from the dual-echo TSE (T2appTSE), and those calculated from the 12-echo MSE (T2appMSE) were mathematically connected by a factor of 1.3 throughout all groups (controls: 1.26 ± 0.02; varTTR-carriers: 1.25 ± 0.02; symptomatic ATTRv amyloidosis: 1.28 ± 0.02), whereas a factor of 0.5 was identified between respective ρ values (controls: 0.47 ± 0.01; varTTR-carriers: 0.47 ± 0.01; symptomatic ATTRv amyloidosis: 0.50 ± 0.02). T2app calculated from both TSE and MSE, distinguished between symptomatic ATTRv (T2appTSE 66.38 ± 2.6; T2appMSE 84.6 ± 3.3) and controls (T2appTSE 58.1 ± 1.0, P = 0.0028; T2appMSE 72.8 ± 0.7, P < 0.0001), whereas differences between varTTR-carriers (T2appTSE 61.8 ± 1.5; T2appMSE 76.7 ± 1.3) and ATTRv amyloidosis were observed only for T2appMSE (P = 0.0082). The ρ value differentiated well between healthy controls (ρTSE 365.1 ± 7.2; ρMSE 170.4 ± 3.8) versus varTTR-carriers (ρTSE 415.7 ± 9.8, P = 0.0027; ρMSE 193.7 ± 5.3, P = 0.0398) and versus symptomatic ATTRv amyloidosis (ρTSE 487.8 ± 17.9; ρMSE 244.7 ± 13.1, P < 0.0001, respectively), but also between varTTR-carriers and ATTRv amyloidosis (ρTSEP = 0.0001; ρMSEP < 0.0001)., Conclusions: Dual-echo TSE and 12-echo MSE sequences provide equally robust and reliable T2-relaxometry data when calculating T2app and ρ. Due to their shorter acquisition time and higher resolution, TSE sequences may be preferred in future magnetic resonance imaging protocols. As a secondary result, ρ can be confirmed as a sensitive biomarker to detect early nerve lesions as it differentiated best among healthy controls, asymptomatic varTTR-carriers, and symptomatic ATTRv amyloidosis, whereas T2app might be beneficial in already manifest ATTRv amyloidosis., Competing Interests: Conflicts of interest and sources of funding: M.W. advises for Akcea Therapeutics, Alnylam Pharmaceuticals, Biogen, Pfizer, and Roche; received lecture honoraria from Akcea Therapeutics, Alnylam Pharmaceuticals, and Biogen; and received financial support for conference attendance from Biogen and Pfizer. U.H. advises for Pfizer and received lecture honoraria from Pfizer, Akcea Therapeutics, and Alnylam Pharmaceuticals. J.C.P. was supported by Abbott, Akcea, Bayer, Boehringer Ingelheim, Daiichi Sankyo, and Pfizer, all outside the submitted work. E.H. received financial reimbursement for consulting and advisory board activities and/or travel support by Akcea, Alnylam, and Pfizer. S.H. was supported by the German Research Council (DFG, SFB 1118). M.B. reports personal fees from Teva, BBraun, Vascular Dynamics, Bayer, Grifols, Merck, Neuroscios, Boehringer Ingelheim, Novartis, research grants from Hopp Foundation, DFG, BMBF, European Union, Stryker, and Siemens, all outside the submitted work. J.K. reports a research grant from Alnylam Pharmaceuticals; the Olympia Morata grant from the Medical Faculty of the University of Heidelberg; personal fees, lecture honoraria, and financial support for conference attendance from Alnylam Pharmaceuticals; lecture honoraria and financial support for conference attendance from Pfizer; and advises for Akcea Therapeutics. For the remaining authors, no conflicts of interest were declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Hereditary transthyretin amyloidosis is caused by pathogenic variants in the TTR gene and typically manifests, alongside cardiac and other organ dysfunctions, with a rapidly progressive sensorimotor and autonomic polyneuropathy (ATTRv-PN) leading to severe disability. While most prospective studies have focussed on endemic ATTRv-PN, real-world data on non-endemic, mostly late-onset ATTRv-PN are limited., Methods: This retrospective study investigated ATTRv-PN patients treated at the Amyloidosis Centre of Heidelberg University Hospital between November 1999 and July 2020. Clinical symptoms, survival, prognostic factors and efficacy of treatment with tafamidis were analysed. Neurologic outcome was assessed using the Coutinho ATTRv-PN stages, and the Peripheral Neuropathy Disability (PND) score., Results: Of 346 subjects with genetic TTR variants, 168 patients had symptomatic ATTRv-PN with 32 different TTR variants identified. Of these, 81.6% had the late-onset type of ATTRv-PN. Within a mean follow-up period of 4.1 ± 2.8 years, 40.5% of patients died. Baseline plasma N-terminal prohormone of brain natriuretic peptide (NT-proBNP) ≥900 ng/l (HR 3.259 [1.421-7.476]; p  = .005) was the main predictor of mortality in multivariable analysis. 64 patients were treated with tafamidis and presented for regular follow-up examinations. The therapeutic benefit of tafamidis was more pronounced when treatment was started early in ATTRv-PN stage 1 (PND scores II vs. I; HR 2.718 [1.258-5.873]; p  = .011)., Conclusions: In non-endemic, mostly late-onset ATTRv-PN, cardiac involvement assessed by NT-proBNP is a strong prognosticator for overall survival. Long-term treatment with tafamidis is safe and efficacious. Neurologic disease severity at the start of treatment is the main predictor for ATTRv-PN progression on tafamidis.

Objective: To quantify peripheral nerve lesions in symptomatic and asymptomatic hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PNP) by analyzing the magnetization transfer ratio (MTR) of the sciatic nerve, and to test its potential as a novel biomarker for macromolecular changes., Methods: Twenty-five patients with symptomatic ATTRv-PNP, 30 asymptomatic carriers of the mutant transthyretin gene (mutTTR), and 20 age-/sex-matched healthy controls prospectively underwent magnetization transfer contrast imaging at 3 Tesla. Two axial three-dimensional gradient echo sequences with and without an off-resonance saturation rapid frequency pulse were conducted at the right distal thigh. Sciatic nerve regions of interest were manually drawn on 10 consecutive axial slices in the images without off-resonance saturation, and then transferred to the corresponding slices that were generated by the sequence with the off-resonance saturation pulse. Subsequently, the MTR and cross-sectional area (CSA) of the sciatic nerve were evaluated. Detailed neurologic and electrophysiologic examinations were conducted in all ATTRv-PNP patients and mutTTR-carriers., Results: Sciatic nerve MTR and CSA reliably differentiated between ATTRv-PNP, mutTTR-carriers, and controls. MTR was lower in ATTRv-PNP (26.4 ± 0.7; P < 0.0001) and in mutTTR-carriers (32.6 ± 0.8; P = 0.0005) versus controls (39.4 ± 2.1), and was also lower in ATTRv-PNP versus mutTTR-carriers (P = 0.0009). MTR correlated negatively with the NIS-LL and positively with CMAPs and SNAPs. CSA was higher in ATTRv-PNP (34.3 ± 1.7 mm 3 ) versus mutTTR-carriers (26.0 ± 1.1 mm 3 ; P = 0.0005) and versus controls (20.4 ± 1.2 mm 3 ; P < 0.0001). CSA was also higher in mutTTR-carriers versus controls., Interpretation: MTR is a novel imaging marker that can quantify macromolecular changes in ATTRv-PNP and differentiate between symptomatic ATTRv-PNP and asymptomatic mutTTR-carriers and correlates with electrophysiology., (© 2020 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Objective: To detect and quantify lesions of the small-caliber sural nerve (SN) in symptomatic and asymptomatic transthyretin familial amyloid polyneuropathy (TTR-FAP) by high-resolution magnetic resonance neurography (MRN) in correlation with electrophysiologic and histopathologic findings., Methods: Twenty-five patients with TTR-FAP, 10 asymptomatic carriers of the mutated transthyretin gene (mut TTR ), and 35 age- and sex-matched healthy controls were prospectively included in this cross-sectional case-control study. All participants underwent 3T MRN with high-structural resolution (fat-saturated, T2-weighted, and double-echo sequences). Total imaging time was ≈45 minutes per patient. Manual SN segmentation was performed from its origin at the sciatic nerve bifurcation to the lower leg with subsequent evaluation of quantitative microstructural and morphometric parameters. Additional time needed for postprocessing was ≈1.5 hours per participant. Detailed neurologic and electrophysiologic examinations were conducted in the TTR group., Results: T2 signal and proton spin density (ρ) reliably differentiated between TTR-FAP (198.0 ± 13.3, 429.6 ± 15.25), mut TTR carriers (137.0 ± 16.9, p = 0.0009; 354.7 ± 21.64, p = 0.0029), and healthy controls (90.0 ± 3.4, 258.2 ± 9.10; p < 0.0001). Marked differences between mut TTR carriers and controls were found for T2 signal ( p = 0.0065) and ρ ( p < 0.0001). T2 relaxation time was higher in patients with TTR-FAP only ( p = 0.015 vs mut TTR carriers, p = 0.0432 vs controls). SN caliber was higher in patients with TTR-FAP vs controls and in mut TTR carriers vs controls ( p < 0.0001). Amyloid deposits were histopathologically detectable in 10 of 14 SN specimens., Conclusions: SN injury in TTR-FAP is detectable and quantifiable in vivo by MRN even in asymptomatic mut TTR carriers. Differences in SN T2 signal between controls and asymptomatic mut TTR carriers are derived mainly from an increase of ρ, which overcomes typical limitations of established diagnostic methods as a highly sensitive imaging biomarker for early detection of peripheral nerve lesions., Classification of Evidence: This study provides Class III evidence that MRN accurately identifies asymptomatic mut TTR carriers., (© 2017 American Academy of Neurology.)