A Hough transform global probabilistic approach to multiple-subject diffusion MRI tractography

A global probabilistic fiber tracking approach based on the voting process provided by the Hough transform is introduced in this work. The proposed framework tests candidate 3D curves in the volume, assigning to each one a score computed from the diffusion images, and then selects the curves with the highest scores as the potential anatomical connections. The algorithm avoids local minima by performing an exhaustive search at the desired resolution. The technique is easily extended to multiple subjects, considering a single representative volume where the registered high-angular resolution diffusion images (HARDI) from all the subjects are non-linearly combined, thereby obtaining population-representative tracts. The tractography algorithm is run only once for the multiple subjects, and no tract alignment is necessary. We present experimental results on HARDI volumes, ranging from simulated and 1.5T physical phantoms to 7T and 4T human brain and 7T monkey brain datasets.     

Determination of cranio-spinal canal compliance distribution by MRI: Methodology and early application in idiopathic intracranial hypertension

Purpose:

To develop a method for derivation of the cranial‐spinal compliance distribution, assess its reliability, and apply to obese female patients with a diagnosis of idiopathic intracranial hypertension (IIH).

Materials and Methods:

Phase contrast‐based measurements of blood and cerebrospinal fluid (CSF) flows to, from, and between the cranial and spinal canal compartments were used with lumped‐parameter modeling to estimate systolic volume and pressure changes from which cranial and spinal compliance indices are obtained. The proposed MRI indices are analogous to pressure volume indices (PVI) currently being measured invasively with infusion‐based techniques. The consistency of the proposed method was assessed using MRI data from seven aged healthy subjects. Measurement reproducibility was assessed using five repeated MR scans from one subject. The method was then applied to compare spinal canal compliance contribution in seven IIH patients and six matched healthy controls.

Results:

In the healthy subjects, as expected, spinal canal contribution was consistently larger than the cranial contribution (average value of 69%). Measurement variability was 8%. In IIH, the spinal canal contribution is significantly smaller than normal controls (60 versus 78%, P < 0.03).

Conclusion:

An MRI‐based method for derivation of compliance indices analogous to PVI has been implemented and applied to healthy subjects. The application of the method to obese IIH patients suggests a spinal canal involvement in the pathophysiology of IIH. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Evolving brand-name and generic drug competition may warrant a revision of the Hatch-Waxman Act

The evolution of pharmaceutical competition since Congress passed the Hatch-Waxman Act in 1984 raises questions about whether the act's intended balance of incentives for cost savings and continued innovation has been achieved. Generic drug usage and challenges to brand-name drugs' patents have increased markedly, resulting in greatly increased cost savings but also potentially reduced incentives for innovators. Congress should review whether Hatch-Waxman is achieving its intended purpose of balancing incentives for generics and innovation. It also should consider whether the law should be amended so that some of its provisions are brought more in line with recently enacted legislation governing approval of so-called biosimilars, or the corollary for biologics of generic competition for small-molecule drugs.     

Identifying Tyrosine Kinase Inhibitor Nonadherence in Chronic Myeloid Leukemia: Subanalysis of TAKE-IT Pilot Study

Background

There are inconsistencies in reports on correlates for nonadherence (NA) to tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML). The diagnostic accuracy of subjective adherence measures using electronic monitoring (EM) as the reference standard is yet to be determined. This study aimed to evaluate correlates of TKI NA using EM and test the diagnostic accuracy of subjective adherence measures.

Depression and suicidal behavior in adolescent inpatients with obsessive compulsive disorder

BACKGROUND: To investigate the prevalence and correlations of suicidal behavior in obsessive compulsive disorder (OCD) among adolescent psychiatric inpatients. METHODS: A total of 348 adolescents, representing consecutive admissions to an adolescent inpatient unit, were assessed. Of these, 40 patients had OCD, 118 had schizophrenia, 59 had an affective disorder, 81 had a conduct disorder and 50 had an eating disorder. In addition, 87 normal community controls were assessed. All subjects were assessed for suicidal behavior by the Childhood Suicide Potential Scale (CSPS), for depression by the Beck Depression Inventory, for impulsiveness by the Impulse Control Scale, for anxiety by the State-Trait Anxiety Scale and for aggression by the Yudowsky Overt Aggression Scale. RESULTS: All the psychiatrically ill subjects, including those with OCD, had high levels of depression, anxiety and impulsiveness, which were far higher than those of the controls. The rate of attempted suicide was, however, much lower in the OCD subjects. In addition, there was a significant inverse correlation between suicidal behavior levels on the CSPS and depression in the OCD subjects, while all other subjects showed the expected significant positive correlation between level of suicidal behavior and depression. LIMITATIONS: This study looked at a referred population and generalization to outpatient and community samples cannot be made. Distinguishing between the primary and the comorbid diagnosis is difficult and some findings are based on small sample size and therefore may be vulnerable to type I error. CONCLUSIONS: Although suicidal ideation and depressive symptoms are common in OCD adolescent inpatients, they seem to be protected against suicide attempts. The inverse relationship between suicidal behavior and depression may mean that suicidal behavior is, in some ways, qualitatively different from that seen in other psychiatrically ill adolescents.