Magnetic resonance imaging and spectroscopy of hepatic iron overload.

▼Objectives: To evaluate the feasibility of addressing liver iron content (LIC) in regularly transfused patients by MR imaging at 3 T based on the signal intensity ratio (SIR). An innovative data analysis approach was developed for this purpose. Methods: 47 consecutive examinations of regularly transfused patients were included. In all cases, we expected high LIC levels. Patients were scanned with MRI at 3 T with multi-echo gradient echo sequences (GRE) at four different flip angles between 20°and 90°with echo times (TE) ranging from 0.9 to 9.8 ms. Spin-echo protocols were acquired to determine the LIC with a reference MRI method working at 1.5 T. 3 T GRE data were analyzed using the liver-to-muscle SIR. Since the method known for 1.5 T was not expected to be applicable for analyzing 3 T data, theoretic dependence of the SIR on the LIC was derived from the equation describing R 2 * signal decay. Obtained SIR values were correlated to reference LIC to get a relation for calculating LIC from SIR quantities. LIC values and their uncertainties were determined from GRE data and correlated to LIC reference values. For two LIC thresholds, the diagnostic accuracy was determined. Results: LIC was reliably determined from SIR in our patient cohort even for large LIC values. Median of LIC uncertainties was 10 %, and the diagnostic accuracy was 0.92 and 0.91, respectively. Conclusion: Determination of even high LIC, resulting in small SIR values, is feasible at 3 T using appropriate SIR analysis.

Section: Signal Noise (Snr)mentioning

confidence: 97%

MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory

Wunderlich

Cario

Bommer

et al. 2016

“…Historically used first [12,13], this method was then further developed by St. Pierre [20] on the basis of the data of 40 patients into a validated, FDA-approved, CE-certified, feebased method under the name Ferriscan ® . The method is based on the fact that the liver signal decreases as the echo time (TE) increases as shown in • ▶ Fig.…”

Section: Spin-echo Sequencementioning

confidence: 99%

“…With the introduction of MRI in the clinical routine, an effect of the liver iron content on the MR signal was identified [12,13]. The first systematic studies on this topic [14 -17] that qualitatively correlated the liver MRI signal with varying degrees of iron overload were published more than twenty years ago.…”

mentioning

confidence: 99%

Noninvasive MRI-Based Liver Iron Quantification: Methodic Approaches, Practical Applicability and Significance

Wunderlich

Cario²,

Juchems

et al. 2016

Pathophysiology of iron overload ▼Normal iron content plays an important role in the physiological processes of the human body. A disturbance to the precisely regulated iron metabolism system has serious consequences. Therefore, for example, iron overload results in oxidative damage to membrane lipids and proteins and in DNA damage that can cause mitochondrial and lysosomal dysfunction, changes in gene expression, and changes in tumor suppressor genes (p53). Organ damage due to iron overload primarily affects the heart and liver as well as the endocrine organs, i. e., the pituitary gland, pancreas, thyroid, parathyroid, and gonads [1]. Cardiac insufficiency and arrhythmia as a result of myocardial siderosis are the most Abstract ▼Due to the dependence of transverse relaxation times T 2 and T 2 * on tissue iron content, MRI offers different options for the determination of iron concentration. These are the timeconsuming spin-echo sequence as well as the gradient-echo sequence. For the latter, several data analysis approaches have been proposed, with different requirements for acquisition and post-processing: the mathematically challenging R 2 * analysis and the signal-intensity ratio method with its high demand on the signal homogeneity of MR images. Furthermore, special procedures currently under evaluation are presented as future prospects: quantitative susceptibility imaging, as a third approach for analyzing gradient echo data, and multicontrast spin-echo using repeated refocusing pulses. MR theory, as far as needed for understanding the methods, is briefly depicted.

“…B. nahe von Luft/Gewebe-Grenzen, macht [21]. In erster Näherung sind die Relaxationsraten R2 (= 1/T2) und R2* (= 1/T2*) proportional zur Eisenkonzentration [24,27]. Darüber hinaus scheint es systematische Unterschiede zwischen R2 (sensitiv auf Ferritin-Eisen) und R2* (sensitiv auf Hämosiderin-Eisen) zu geben [28].…”

Section: Formen Der Eisenüberladungunclassified

Eisenquantifizierung mittels MRT bei Eisenüberladung

Schönnagel

Fischer

Nielsen

et al. 2013

Zusammenfassung Eisen ist als essenzielles Spurenelement in viele Stoffwechselaktivit?ten involviert. Wie wichtig eine optimale Eisenversorgung ist zeigt, dass nach WHO Angaben ca. 30?% der Weltbev?lkerung an einer eisenmangelbedingten An?mie leidet. Dagegen ist die heredit?re H?mochromatose die h?ufigste monogen vererbte Erkrankung (Pr?valenz homozygoter Merkmalstr?ger in Deutschland 1:200???300). W?hrend die Diagnostik und Therapie einer Eisenmangelan?mie einem relativ einfachen Prozedere unterliegen, stellen die Diagnose und insbesondere die Quantifizierung der Organeisen?berladung eine ungleich schwerere Herausforderung dar. Dies ist von gro?er klinischer Bedeutung, da die Gesamtkonzentration des K?rper- bzw. Organeisens der ausschlaggebende Parameter f?r die Prognose bei Eisen?berladungen ist. So wurde 2001 auf dem Internationalen Workshop des NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases) dokumentiert, dass ein klarer klinischer Nutzen f?r die nicht invasive, quantitative, sichere und akkurate Bestimmung des K?rpereisengehalts zur Verbesserung der Diagnose und Therapie bei Eisen?berladungskrankheiten besteht.