Biomedical subjects

Beth A Harkness

Publications and source records attributed to Beth A Harkness.

4 recordsLinked to original sources

PubMed2006

Transient ischemic dilatation of the left ventricle with severe post stress left ventricular dysfunction in the setting of severe aortic stenosis and normal coronary arteries.

Transient ischemic dilatation (TID) of the left ventricle observed during single photon myocardial perfusion emission computed tomography (SPECT) is an important non-perfusion finding that may not only suggest underlying significant (usually multi-vessel) coronary artery disease (CAD) but also an independent prognostic factor of adverse outcomes regardless of abnormal or normal perfusion finding. We present a patient with no significant epicardial coronary disease who had significant TID and considerable decrease in the left ventricular ejection fraction with left ventricular dilatation after a rest-stress Tc-99 tetrofosmin SPECT study in the setting of severe aortic stenosis. With the advent of gated SPECT imaging the additive value of determining rest and post stress EF, as demonstrated in this case, aided in the recognition of TID and transient decrease in the left ventricular ejection fraction. These are not necessarily related to obstructive epicardial coronary disease, but are a result of severe aortic valve disease causing subendocardial ischemia in the setting of multilple other non-ischemic etiologies of TID such as left ventricular hypertrophy and diabetes mellitus.

Adenosine↗

PubMed2002

Whole body FDG-PET for the evaluation and staging of small cell lung cancer: a preliminary study.

[F18]-2-deoxy-2fluoro-D-glucose positron emission tomography (FDG-PET) is increasingly used in the diagnosis and staging of lung cancer. Despite its positive performance characteristics in non-small cell lung cancer (NSCLC), the role of FDG-PET in the staging of small cell lung cancer (SCLC) remains to be determined. We designed a prospective study to address this question. Eighteen patients with SCLC were enrolled prospectively to undergo total body FDG-PET in addition to conventional staging procedures (chest computed tomography (CT), abdominal CT, cranial CT or magnetic resonance imaging (MRI), and bone scan/bone marrow biopsy). The agreement between FDG-PET and conventional staging modalities in identifying the presence or absence of metastatic disease was compared using the Veterans Administration (VA) cooperative staging system for staging. Overall staging by FDG-PET agreed with conventional staging exams in 15/18 (83%) patients (kappa=0.67), which included eight extensive and seven limited cases. FDG-PET showed more extensive disease in two of the three patients for which FDG-PET and conventional staging disagreed. These data suggest that total body FDG-PET may be useful in the staging, treatment planning, and prognostication of SCLC. Whether FDG-PET will replace other more established staging modalities remains to be determined by larger prospective randomized controlled studies.

Carcinoma, Small Cell↗

PubMed2002

Angular disparity in ETACT scintimammography.

Emission tuned aperture computed tomography (ETACT) has been previously shown to have the potential for the detection of small tumors (<1 cm) in scintimammography. However, the optimal approach to the application of ETACT in the clinic has yet to be determined. Therefore, we sought to determine the effect of the angular disparity between the ETACT projections on image quality through the use of a computer simulation. A small, spherical tumor of variable size (5, 7.5 or 10 mm) was placed at the center of a hemispherical breast (15 cm diameter). The tumor to nontumor ratio was either 5:1 or 10:1. The detector was modeled to be a gamma camera fitted with a 4-mm-diam pinhole collimator. The pinhole-to-detector and the pinhole-to-tumor distances were 25 and 15 cm, respectively. A ray tracing technique was used to generate three sets of projections (10 degrees, 15 degrees, and 20 degrees, angular disparity). These data were blurred to a resolution consistent with the 4 mm pinhole. The TACT reconstruction method was used to reconstruct these three image sets. The tumor contrast and the axial spatial resolution was measured. Smaller angular disparity led to an improvement in image contrast but at a cost of degraded axial spatial resolution. The improvement in contrast is due to a slight improvement in the in-plane spatial resolution. Since improved contrast should lead to better tumor detectability, smaller angular disparity should be used. However, the difference in contrast between 10 degrees and 15 degrees was very slight and therefore a reasonable clinical choice for angular disparity is 15 degrees.

Breast↗

PubMedDate not supplied

Evaluation of the quantitative capability of a high-resolution positron emission tomography scanner for small animal imaging.

OBJECTIVE: The quantitative capability of a positron emission tomography scanner for small animal imaging was evaluated in this study. METHODS: The microPET P4 (Concorde Microsystems, Knoxville, TN) scanner's capability for dynamic imaging and corrections for radioactive decay, dead time, and attenuation were evaluated. Rat brain and heart studies with and without attenuation correction were compared. A calibration approach to convert the data to nanocuries per milliliter was implemented. Calibration factors were determined using calibration phantoms of 2 sizes with and without attenuation correction. Quantitation was validated using the MiniPhantom (Data Spectrum, Chapel Hill, NC) with hot features (5:1 ratio) of different sizes (4, 6.4, 8, 13, and 16 mm). RESULTS: The microPET P4 scanner's ability to acquire dynamic studies and to correct for decay, dead time, and attenuation was demonstrated. The microPET P4 scanner provided accurate quantitation to within 6% for features larger than 10 mm. Sixty percent of object contrast was retained for features as small as 4 mm. CONCLUSIONS: The microPET P4 scanner can provide accurate quantitation.

Animals↗