Automated low-contrast pattern recognition algorithm for magnetic resonance image quality assessment.

PURPOSE: Low contrast (LC) detectability is a common test criterion for diagnostic radiologic quality control (QC) programs. Automation of this test is desirable in order to reduce human variability and to speed up analysis. However, automation is challenging due to the complexity of the human visual perception system and the ability to create algorithms that mimic this response. This paper describes the development and testing of an automated LC detection algorithm for use in the analysis of magnetic resonance (MR) images of the American College of Radiology (ACR) QC phantom. METHODS: The detection algorithm includes fuzzy logic decision processes and various edge detection methods to quantify LC detectability. Algorithm performance was first evaluated using a single LC phantom MR image with the addition of incremental zero mean Gaussian noise resulting in a total of 200 images. A c-statistic was calculated to determine the role of CNR to indicate when the algorithm would detect ten spokes. To evaluate inter-rater agreement between experienced observers and the algorithm, a blinded observer study was performed on 196 LC phantom images acquired from nine clinical MR scanners. The nine scanners included two MR manufacturers and two field strengths (1.5 T, 3.0 T). Inter-rater and algorithm-rater agreement was quantified using Krippendorff's alpha. RESULTS: For the Gaussian noise added data, CNR ranged from 0.519 to 11.7 with CNR being considered an excellent discriminator of algorithm performance (c-statistic = 0.9777). Reviewer scoring of the clinical phantom data resulted in an inter-rater agreement of 0.673 with the agreement between observers and algorithm equal to 0.652, both of which indicate significant agreement. CONCLUSIONS: This study demonstrates that the detection of LC test patterns for MR imaging QC programs can be successfully developed and that their response can model the human visual detection system of expert MR QC readers.

Intravenous autologous bone marrow mononuclear cells for ischemic stroke.

OBJECTIVE: Cellular therapy is an investigational approach for stroke. Mononuclear cells (MNCs) from the bone marrow reduce neurological deficits in animal stroke models. We determined if autologous MNC infusion was feasible and safe in patients with ischemic stroke. METHODS: We conducted an open-label prospective study of a bone marrow harvest followed by readministration of autologous MNCs in 10 patients, 18 to 80 years old, with acute middle cerebral artery ischemic stroke. Bone marrow was aspirated from the iliac crest, and MNCs were separated at a Good Manufacturing Practices facility and administered intravenously up to a maximum of 10 million cells/kg. The harvest and infusion had to occur between 24 and 72 hours after stroke. Patients were monitored for 6 months. RESULTS: Bone marrow aspiration was successfully completed in all patients. Eight received 10 million cells/kg, and 2 received ≥7 million cells/kg. There were no significant adverse events related to harvest or infusion. Two patients had infarct expansion between enrollment and harvest and underwent hemicraniectomy after cell infusion. One patient died at 40 days due to a pulmonary embolism related to the stroke. There were no study-related severe adverse events. Median National Institutes of Health Stroke Scale score was 13 before harvest, 8 at 7 days, and 3 at 6 months. At 6 months, all surviving patients had shifted down by at least 1 point on the modified Rankin Scale compared to day 7. Seven of 10 patients achieved a Barthel Index ≥90. INTERPRETATION: This study suggests that a bone marrow harvest and reinfusion of autologous MNCs were safe and feasible in acute stroke patients.

Pharmacological deep vein thrombosis prophylaxis does not lead to hematoma expansion in intracerebral hemorrhage with intraventricular extension.

BACKGROUND AND PURPOSE: Patients with intracerebral hemorrhage (ICH) are at high risk for development of deep venous thrombosis. Current guidelines state that low-dose subcutaneous low molecular weight heparin or unfractionated heparin may be considered at 3 to 4 days from onset. However, insufficient data exist on hematoma volume in patients with ICH before and after pharmacological deep venous thrombosis prophylaxis, leaving physicians with uncertainty regarding the safety of this practice. METHODS: We identified patients from our stroke registry (June 2003 to December 2007) who presented with ICH only or ICH+intraventricular hemorrhage and received either low molecular weight heparin subcutaneously or unfractionated heparin within 7 days of admission and had a repeat CT scan performed within 4 days of starting deep venous thrombosis prophylaxis. We calculated the change in hematoma volume from the admission and posttreatment CTs. Hematoma volume was calculated using the ABC/2 method and intraventricular hemorrhage volumes were calculated using a published method of hand drawn regions of interest. RESULTS: We identified 73 patients with a mean age of 63 years and median National Institutes of Health Stroke Scale score 11.5. The mean baseline total hematoma volume was 25.8 mL±23.2 mL. There was an absolute change in hematoma volume from pre- and posttreatment CT of -4.3 mL±11.0 mL. Two patients developed hematoma growth. Repeat analysis of patients given pharmacological deep venous thrombosis prophylaxis within 2 or 4 days after ICH found no increase in hematoma size. CONCLUSIONS: Pharmacological deep venous thrombosis prophylaxis given subcutaneously in patients with ICH and/or intraventricular hemorrhage in the subacute period is generally not associated with hematoma growth.