Measurements of hepatic iron concentration (HIC) are important predictors of transfusional iron burden and long-term outcome in patients with transfusiondependent anemias. The goal of this work was to develop a readily available, noninvasive method for clinical HIC measurement. The relaxation rates R2 (1/ T2) and R2* (1/ T2*) measured by magnetic resonance imaging (MRI) have different advantages for HIC estimation. This article compares noninvasive iron estimates using both optimized R2 and R2* methods in 102 patients with iron overload and 13 controls. In the iron-overloaded group, 22 patients had concurrent liver biopsy. R2 and R2* correlated closely with HIC (r 2 > .95) for HICs between 1.33 and 32.9 mg/g, but R2 had a curvilinear relationship to HIC. Of importance, the R2 calibration curve was similar to the curve generated by other researchers, despite significant differences in technique and instrumentation. Combined R2 and R2* measurements did not yield more accurate results than either alone. Both R2 and R2* can accurately measure hepatic iron concentration throughout the clinically relevant range of HIC with appropriate MRI acquisition techniques. (Blood.

Cardiac T2* (magnetic resonance imaging relaxation parameter) is abnormally low in approximately 40% of adults with thalassemia major (TM), suggesting myocardial iron deposition, but it is unknown at what age this occurs. To address this question, we measured cardiac T2* and function in 19 young patients (aged 7-26 years) with TM as well as 17 patients receiving long-term transfusions for sickle cell anemia (SCA) matched for age, sex, and liver iron content. Cardiac T2* was normal in all of the SCA patients but was low (high iron) in 8 of 19 TM patients. Abnormal T2* was observed only in the TM patients receiving transfusions for 13 years or longer and was correlated with ferritin but not liver iron levels. Cardiac dysfunction was present in 3 of the 8 patients with low T2*. Cardiac T2* changes have a long latency relative to liver iron accumulation. Total transfusional burden is a significant independent risk factor for low cardiac T2* and may partially account for differences observed between patients with SCA and

Abusive head trauma (AHT) is the leading cause of fatal head injuries in children younger than 2 years. A multidisciplinary team bases this diagnosis on history, physical examination, imaging and laboratory findings. Because the etiology of the injury is multifactorial (shaking, shaking and impact, impact, etc.) the current best and inclusive term is AHT. There is no controversy concerning the medical validity of the existence of AHT, with multiple components including subdural hematoma, intracranial and spinal changes, complex retinal hemorrhages, and rib and other fractures that are inconsistent with the provided mechanism of trauma. The workup must exclude medical diseases that can mimic AHT. However, the courtroom has become a forum for speculative theories that cannot be reconciled with generally accepted medical literature. There is no reliable medical evidence that the following processes are causative in the constellation of injuries of AHT: cerebral sinovenous thrombosis, hypoxic-ischemic injury, lumbar puncture or dysphagic choking/vomiting. There is no substantiation, at a time remote from birth, that an asymptomatic birth-related subdural hemorrhage can result in rebleeding and sudden collapse. Further, a diagnosis of AHT is a medical conclusion, not a legal determination of the intent of the perpetrator or a diagnosis of murder. We hope that this consensus document reduces confusion by recommending to judges and jurors the tools necessary to distinguish genuine evidence-based opinions of the relevant medical community from legal arguments or etiological speculations that are unwarranted by the clinical findings, medical evidence and evidence-based literature.

Background-Transfusional therapy for thalassemia major and sickle cell disease can lead to iron deposition and damage to the heart, liver, and endocrine organs. Iron causes the MRI parameters T1, T2, and T2* to shorten in these organs, which creates a potential mechanism for iron quantification. However, because of the danger and variability of cardiac biopsy, tissue validation of cardiac iron estimates by MRI has not been performed. In this study, we demonstrate that iron produces similar T1, T2, and T2* changes in the heart and liver using a gerbil iron-overload model. Methods and Results-Twelve gerbils underwent iron dextran loading (200 mg · kg Ϫ1 · wk

Purpose: To optimize R2*(1/T2*) measurements for cardiac iron detection in sickle cell and thalassemia patients. Materials and Methods:We studied 31 patients with transfusion-dependent sickle cell disease and 48 patients with thalassemia major; myocardial R2* was assessed in a single midpapillary slice using a gated gradient-echo pulse sequence. Pixel-wise maps were coregistered among the patients to determine systematic spatial fluctuations in R2*. The contributions of minimum TE, echo spacing, signal-decay model, and region-of-interest (ROI) choice were compared in synthetic and acquired images.Results: Cardiac relaxivity demonstrated characteristic circumferential variations regardless of the degree of iron overload. Within the interventricular septum, a gradient in R2* from right to left ventricle was noted at high values. Pixel-wise and ROI techniques yielded nearly identical values. Signal decay was exponential but a constant offset or second exponential term was necessary to avoid underestimation at high iron concentration. Systematic underestimation of R2* was observed for higher minimum TE, limiting the range of iron concentrations that can be profiled. Fat-water oscillations, although detectable, represented only 1% of the total signal. Conclusion:Clinical cardiac R2* measurements should be restricted to the interventricular septum and should have a minimum TE Յ 2 msec. ROI analysis techniques are accurate; however, offset-correction is essential.

Between birth and late adolescence, the human brain undergoes exponential maturational changes. Using in vivo magnetic resonance spectroscopy, we determined the developmental profile for 6 metabolites in 5 distinct brain regions based on spectra from 309 children from 0 to 18 years of age. The concentrations of N-acetyl-aspartate (an indicator for adult-type neurons and axons), creatine (energy metabolite), and glutamate (excitatory neurotransmitter) increased rapidly between birth and 3 months, a period of rapid axonal growth and synapse formation. Myo-inositol, implicated in cell signaling and a precursor of membrane phospholipid, as well as an osmolyte and astrocyte marker, declined rapidly during this period. Choline, a membrane metabolite and indicator for de novo myelin and cell membrane synthesis, peaked from birth until approximately 3 months, and then declined gradually, reaching a plateau at early childhood. Similarly, taurine, involved in neuronal excitability, synaptic potentiation, and osmoregulation, was high until approximately 3 months and thereafter declined. These data indicate that the first 3 months of postnatal life are a critical period of rapid metabolic changes in the development of the human brain. This study of the developmental profiles of the major brain metabolites provides essential baseline information for future analyses of the pediatric health and disease.

Adult subjects with classical phenylketonuria (PKU) who were diagnosed and treated neonatally participated in this long-term follow-up study. Twenty-four subjects received neuropsychological (NP) assessment and a subset received magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to identify: (1) pattern of cognitive dysfunction; (2) effect of high blood phenylalanine (Phe) level at time of cognitive testing; and (3) treatment variables that may be associated with cognitive difficulties in adulthood. All subjects had average IQ except one subject in the borderline range. Diet was initiated by the 15th day of life. All subjects except one were on diet until age 6 years (mean years of treatment = 15). Blood Phe levels at cognitive testing ranged from 157 to 1713 micromol/L (mean = 1038); 11 subjects had levels < 1000 micromol/L and 13 subjects had levels >1000 micromol/L. Results suggest that adults with early-treated PKU demonstrate specific cognitive deficits, a number of which are associated with the frontal and temporal area of the brain. Deficits were noted in several domains including executive functioning, attention, verbal memory, expressive naming and verbal fluency. Self-report measures of depression and anxiety were generally in the normal/mild range. The group with a Phe level > 1000 micromol/L scored lower than the group with Phe level < 1000 micromol/L on measures of focused attention, verbal fluency, reaction time, verbal recognition memory, visual memory and naming. Tests of cognitive functioning were often correlated with measures of treatment during childhood rather than with Phe level at the time of cognitive testing. Subjects with abnormal MRI scored significantly lower on two cognitive tests (Trails A and CVLT Recognition Memory). We found no significant correlation between current brain Phe level obtained through MRS (n = 10) and neuropsychological functioning. Future longitudinal investigation with a larger sample size will assist in clarifying the aetiology of neuropsychological deficits and association with treatment history.

Iron-induced cardiac dysfunction is a leading cause of death in transfusion-dependent anemia. MRI relaxation rates R 2 (1/T 2 ) and R* 2 (1/T* 2 ) accurately predict liver iron concentration, but their ability to predict cardiac iron has been challenged by some investigators. Studies in animal models support similar R 2 and R* 2 behavior with heart and liver iron, but human studies are lacking. To determine the relationship between MRI relaxivities and cardiac iron, regional variations in R 2 and R* 2 were compared with iron distribution in one freshly deceased, unfixed, iron-loaded heart. R 2 and R* 2 were proportionally related to regional iron concentrations and highly concordant with one another within the interventricular septum. A comparison of postmortem and in vitro measurements supports the notion that cardiac R* 2 should be assessed in the septum rather than the whole heart. These data, along with measurements from controls, provide bounds on MRI-iron calibration curves in human heart and further support the clinical use of cardiac MRI in iron-overload syndromes. Magn Reson Med 56: 681-686, 2006.