Considerations regarding the micromagnetic resonance relaxometry technique for rapid label-free malaria diagnosis

Karl, Stephan; Müeller, Ivo; Pierre, Timothy G. St.

doi:10.1038/nm.3811

Cited by 8 publications

(8 citation statements)

References 4 publications

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“…Several approaches to exploit these magnetic properties for diagnostic purposes have been proposed [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] and some of these techniques showed promise under laboratory conditions. However, only a few magneto-optical (MO) methods have been tested in operational settings in malaria endemic countries or with samples collected from malaria-infected patients in endemic countries.…”

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confidence: 99%

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

et al. 2021

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Improved methods for malaria diagnosis are urgently needed. Here, we evaluate a novel method named rotating-crystal magneto-optical detection (RMOD) in 956 suspected malaria patients in Papua New Guinea. RMOD tests can be conducted within minutes and at low cost. We systematically evaluate the capability of RMOD to detect infections by directly comparing it with expert light microscopy, rapid diagnostic tests and polymerase chain reaction on capillary blood samples. We show that compared to light microscopy, RMOD exhibits 82% sensitivity and 84% specificity to detect any malaria infection and 87% sensitivity and 88% specificity to detect Plasmodium vivax. This indicates that RMOD could be useful in P. vivax dominated elimination settings. Parasite density correlates well with the quantitative magneto-optical signal. Importantly, residual hemozoin present in malaria-negative patients is also detectable by RMOD, indicating its ability to detect previous infections. This could be exploited to reveal transmission hotspots in low-transmission settings.

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confidence: 99%

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

et al. 2021

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“…Moreover, its unique intrinsic magnetic and optical properties have prompted researchers to consider HZ a promising biomarker for the design of new diagnostic tools. Recently, Han et al 9,10,11 and Karl et al 12,13 proposed a new technique for quantitative and rapid detection of P. falciparum ‐infected RBCs by means of 1 H‐nuclear MR relaxometry (MRR) that relies on the detection of the HZ crystals produced by P. falciparum in the host RBCs. HZ crystals display a relatively large paramagnetic susceptibility, which is responsible for changes in the transverse relaxation rate constant ( R 2 = 1 /T 2 ) of 1 H‐ water resonance 14‐16 …”

Section: Introductionmentioning

confidence: 99%

Relaxometric studies of erythrocyte suspensions infected by Plasmodium falciparum: a tool for staging infection and testing anti‐malarial drugs

Gregorio

Ferrauto

Schwarzer

et al. 2020

Magnetic Resonance in Med

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Purpose Malaria is a global health problem with the most malignant form caused by Plasmodium falciparum (P. falciparum). Parasite maturation in red blood cells (RBCs) is accompanied by changes including the formation of paramagnetic hemozoin (HZ) nanocrystals, and increased metabolism and variation in membrane lipid composition. Herein, MR relaxometry (MRR) was applied to investigate water exchange across RBCs’ membrane and HZ formation in parasitized RBCs. Methods Transverse water protons relaxation rate constants (R2 = 1/T2) were measured for assessing HZ formation in P. falciparum‐parasitized human RBCs. Moreover, water exchange lifetimes across the RBC membrane (τi) were assessed by measuring longitudinal relaxation rate constants (R1 = 1/T1) at 21.5 MHz in the presence of a gadolinium complex dissolved in the suspension medium. Results τi increased after invasion of parasites (ring stage, mean τi/τi0 = 1.234 ± 0.022) and decreased during maturation to late trophozoite (mean τi/τi0 = 0.960 ± 0.075) and schizont stages (mean τi/τi0 = 1.019 ± 0.065). The HZ accumulation in advanced stages was revealed by T2‐shortening. The curves reporting R2 (1/T2) vs. magnetic field showed different slopes for non‐parasitized RBCs (npRBCs) and parasitized RBCs (pRBCs), namely 0.003 ± 0.001 for npRBCs, 0.009 ± 0.002, 0.028 ± 0.004 and 0.055 ± 0.002 for pRBCs at ring‐, early trophozoite‐, and late trophozoite stage, respectively. Antimalarial molecules dihydroartemisinin and chloroquine elicited measurable changes in parasitized RBCs, namely dihydroartemisinin modified τi, whereas the interference of chloroquine with HZ formation was detectable by a significant T2 increase. Conclusions MRR can be considered a useful tool for reporting on P. falciparum blood stages and for screening potential antimalarial molecules.

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“…However, evaluations of magnet-based tests in larger in-field trials are rare and have, so far, been disillusioning. [16–18, 28, 29]…”

Section: Introductionmentioning

confidence: 99%

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

Arndt

Koleala

Orbán

et al. 2020

Preprint

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Improved methods for malaria diagnosis are urgently needed. Here, we tested a novel rotating-crystal magneto-optical diagnostic (RMOD) test in 964 suspected malaria patients in Papua New Guinea. RMOD tests can be obtained within minutes and at low cost. Capillary blood samples were also subjected to rapid diagnostic tests, expert light microscopy and polymerase chain reaction to systematically evaluate the capability of RMOD to detect infections. Compared to light microscopy, as the gold standard, RMOD exhibited 82% sensitivity and 84% specificity to detect any malaria infection. This increased to 87% sensitivity and 88% specificity for Plasmodium vivax, indicating that RMOD could be useful in P. vivax dominated elimination settings. Parasite density correlated well with the quantitative magneto-optical signal. Importantly, residual hemozoin present in malaria negative patients was also detectable by RMOD, indicating its ability to detect previous infections, which can be exploited to reveal transmission hotspots in low-transmission settings.

show abstract

Considerations regarding the micromagnetic resonance relaxometry technique for rapid label-free malaria diagnosis

Cited by 8 publications

References 4 publications

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

Relaxometric studies of erythrocyte suspensions infected by Plasmodium falciparum: a tool for staging infection and testing anti‐malarial drugs

Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

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