Biomedical subjects

Jeffrey Solomon

Publications and source records attributed to Jeffrey Solomon.

9 recordsLinked to original sources

PubMed2006

Segmentation of brain tumors in 4D MR images using the hidden Markov model.

Tumor size is an objective measure that is used to evaluate the effectiveness of anticancer agents. Responses to therapy are categorized as complete response, partial response, stable disease and progressive disease. Implicit in this scheme is the change in the tumor over time; however, most tumor segmentation algorithms do not use temporal information. Here we introduce an automated method using probabilistic reasoning over both space and time to segment brain tumors from 4D spatio-temporal MRI data. The 3D expectation-maximization method is extended using the hidden Markov model to infer tumor classification based on previous and subsequent segmentation results. Spatial coherence via a Markov Random Field was included in the 3D spatial model. Simulated images as well as patient images from three independent sources were used to validate this method. The sensitivity and specificity of tumor segmentation using this spatio-temporal model is improved over commonly used spatial or temporal models alone.

Brain Neoplasms↗

PubMed2006

Evaluation of palliative stenting for management of malignant urethral obstructions in dogs.

OBJECTIVE: To evaluate use of balloon-expandable and self-expanding metallic stents in management of malignant urethral obstructions in dogs. DESIGN: Original study. ANIMALS: 12 dogs with malignant urethral obstructions. PROCEDURES: The extent and location of urethral obstructions and the diameter of adjacent unaffected luminal segments were determined by use of fluoroscopically guided wires and measuring catheters. Stents were chosen to extend approximately 1 cm proximal and distal to the obstruction. Stent diameters were chosen to be approximately 10% greater than the diameter of healthy portions of the urethra to prevent displacement. Stents were placed in the urethra under fluoroscopic guidance to restore luminal patency. RESULTS: 3 dogs received balloon-expandable metallic stents, and 9 dogs received self-expanding metallic stents. The placement procedures were rapid, safe, and effective at restoring luminal patency and were not associated with major complications. Complications included recurrent urethral obstruction secondary to blood clot formation and urethral edema in 1 dog and stent dislodgement into the urinary bladder in 1 dog. All dogs were able to urinate immediately after the procedure. Nine dogs (3/4 females and 6/8 males) were continent or mildly incontinent after stent placement. Of the remaining 3 dogs, 2 developed severe incontinence and 1 had an atonic bladder. Seven dogs were considered to have good to excellent outcome, 3 had fair outcome, and 2 had poor outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Transurethral placement of metallic stents was a safe and effective palliative treatment option for dogs with malignant urethral obstructions.

Animals↗

PubMed2006

Multidimensional volumetric imaging of pulmonary infiltrates for measuring therapeutic response to antifungal therapy in experimental invasive pulmonary aspergillosis.

Pulmonary infiltrates in neutropenic hosts with invasive pulmonary aspergillosis are caused by vascular invasion, hemorrhagic infarction, and tissue necrosis. Monitoring the dynamics of pulmonary infiltrates of invasive aspergillosis is an important tool for assessing response to antifungal therapy. We, therefore, introduced a multidimensional volumetric imaging (MDVI) method for analysis of the response of the volume of pulmonary infiltrates over time to antifungal therapy in experimental invasive pulmonary aspergillosis (IPA) in persistently neutropenic rabbits. We developed a semiautomatic method to measure the volume of lung lesions, which was implemented as an extension of the MEDx visualization and analysis software using ultrafast computerized tomography (UFCT). Volumetric infiltrate measures were compared with UFCT reading, histopathological resolution of lesions, microbiological clearance of Aspergillus fumigatus, and galactomannan index (GMI). We also studied the MDVI method for consistency and reproducibility in comparison to UFCT. Treatment groups consisted of deoxycholate amphotericin B (DAMB) at 0.5 or 1 mg/kg of body weight/day and untreated controls (UC). Therapeutic monitoring of pulmonary infiltrates using MDVI demonstrated a significant decrease in the infiltrate volume in DAMB-treated rabbits in comparison to UC (P<or=0.001). Volumetric data by MDVI correlated with conventional CT pulmonary scores (r=0.83, P<or=0.001). These results correlated with validated biological endpoints: pulmonary infarct scores (r=0.85, P<or=0.001), lung weights (r=0.76, P<or=0.01), residual fungal burden (r=0.65, P<or=0.05), and GMI (r=0.78, P<or=0.01). MDVI correlated with key biological markers, improved the objectivity of radiological assessment of therapeutic response to antifungal therapy, and warrants evaluation for monitoring therapeutic response in immunocompromised patients with invasive aspergillosis.

Amphotericin B↗

PubMed2004

Computer-assisted detection of subcutaneous melanomas: feasibility assessment.

RATIONALE AND OBJECTIVES: Subcutaneous melanomas may be missed on computed tomography because of their peripheral location or perceived unimportance, yet they can have clinical significance. The use of a novel computer-assisted detection scheme to locate subcutaneous melanoma lesions in body CT images was investigated. MATERIALS AND METHODS: The detection software segments subcutaneous fat from the rest of the body and searches for soft tissue density lesions that match a size and shape constraint. Sensitivity and specificity of the proposed method was analyzed by comparing automated lesion detection results in eight patients with 118 subcutaneous melanomas with ground truth data derived from manual tracings of a trained observer. RESULTS: The sensitivity of subcutaneous melanoma detection was 86%. The false-positive rate was 3.1 per slice. Analysis of the false-positives showed that the most common cause was incorrect classification of muscle as a nodule. CONCLUSION: This study showed the feasibility of a fully automatic subcutaneous melanoma lesion detection system having good sensitivity. The false-positive rate was high, but avenues for further reduction were identified.

Adult↗

PubMed2004

Automated detection and volume measurement of plexiform neurofibromas in neurofibromatosis 1 using magnetic resonance imaging.

An automated technique for segmentation and volumetric measurement of plexiform neurofibromas (PN) in neurofibromatosis 1 using short T1-inversion recovery magnetic resonance images is presented. The algorithm described implements heuristics derived from human-based recognition of lesions. This technique combines region-based with boundary-based segmentation. Two observers, who performed semi-automated volume calculations and manual tracings to estimate tumor volume, validated this method on 9 PNs of different size and location. This automated method was reproducible (coefficient of variation 0.6-5.6%), yielded similar results to manual tumor tracings (R = 0.999) and will likely improve the ability to measure PNs in ongoing clinical trials.

Algorithms↗

PubMed2003

Intraoperative infrared functional imaging of human brain.

We hypothesized that it would be possible to detect the distribution of cortical activation by using a sensitive, rapid, high-resolution infrared imaging technique to monitor changes in local cerebral blood flow induced by changes in focal cortical metabolism. In a prospective study, we recorded in 21 patients the emission of infrared radiation from the exposed human cerebral cortex at baseline, during language and motor tasks, and during stimulation of the contralateral median nerve using an infrared camera (sensitivity 0.02 degrees C). The language and sensorimotor cortex was identified by standard mapping methods (cortical stimulation, median nerve somatosensory-evoked potential, functional magnetic resonance imaging), which were compared with infrared functional localization. The temperature gradients measured during surgery are dominated by changes in local cerebral blood flow associated with evoked functional activation. The distribution of the evoked temperature changes overlaps with, but extends beyond, functional regions identified by standard mapping techniques. The distribution observed via infrared mapping is consistent with distributed and complex functional representation of the cerebral cortex, rather than the traditional concept of discrete functional loci demonstrated by brief cortical stimulation during surgery and by noninvasive functional imaging techniques. By providing information on the spatial and temporal patterns of sensory-motor and language representation, infrared imaging may prove to be a useful approach to study brain function.

Adult↗

PubMed2002

Placement of a vena cava filter with an antecubital approach.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the use of an antecubital venous approach for inferior vena cava (IVC) filter placement. MATERIALS AND METHODS: An IVC filter was placed in 26 patients (15 men, 11 women) in whom the antecubital vein was the preferred access site. An antecubital vein was accessed with ultrasound guidance and used for IVC filter placement. This same access site was used to place a peripherally inserted central catheter (PICC) in 17 of the 26 patients. Access was obtained via the basilic vein in 15 patients (58%), brachial vein in eight (31%), and cephalic vein in three (12%). RESULTS: The IVC filter was successfully placed in the infrarenal vena cava in all 26 patients (100%) by using an antecubital vein for access. All filters deployed appropriately without complication. No complications occurred during PICC placement. CONCLUSION: The IVC filter can be safely placed via an antecubital vein. When clinically necessary, this site can provide convenient access for the PICC placement.

Catheterization, Peripheral↗

PubMed2002

Stent graft repair of visceral artery aneurysms.

Endovascular techniques with coil embolization have been used in certain visceral aneurysm cases, often resulting in sacrifice of the involved visceral vessel and end-organ thrombosis. We describe two cases in which stent grafts were used to treat these aneurysms, allowing preservation of visceral artery and end-organ flow while completely excluding the aneurysm. Case 1 was a 50-year-old morbidly obese woman with a history of multiple abdominal operations for renal cell carcinoma who was found to have a large splenic artery aneurysm. A 12-mm x 50-mm Wallgraft endoprosthesis (Boston Scientific, Watertown, Mass) was placed across the aneurysm from a femoral approach. The aneurysm was completely excluded, and splenic artery flow was preserved. A subsequent computed tomographic scan showed complete aneurysm exclusion and preserved flow to the spleen. Case 2 was a 73-year-old man with hypertension with back pain who was found with computed tomographic scan to have an 8-cm hepatic artery aneurysm. Arteriography showed a large saccular aneurysm arising from the mid portion of the common hepatic artery. Two 5-mm x 26-mm Jostent stent grafts (Jomed, Alpharetta, Ga) were placed across the aneurysm neck, completely excluding the aneurysm and preserving hepatic artery flow. The patient became pain free, and subsequent duplex ultrasound scan showed a thrombosed aneurysm with normal hepatic artery flow. Stent graft techniques show early promise as a safe and effective treatment of visceral artery aneurysms in selected patients at high risk. Endografts, unlike coil embolization, exclude the aneurysm and preserve end organ perfusion. Determining the durability of this type of therapy will require further study.

Aged↗

PubMed2002

Quantification of brain lesions using interactive automated software.

We developed an interactive program, Analysis of Brain Lesions (ABLe) so that researchers studying the effects of brain lesions on cognition could have a user-friendly tool that could quantitatively characterize such lesions. The program was prepared in Tcl/Tk and will run on any UNIX or PC LINUX platform with the MEDx medical imaging software package. The ABLe is almost completely automated and determines the brain lesion size as well as which cytoarchitectonic brain regions (Brodmann areas) are contained within the boundaries of the lesion. Lesion data from multiple subjects can be grouped together and the degree of lesion overlap displayed. All images are analyzed and displayed within standard Talairach coordinate space, and the precision of the match between the ABLe Brodmann area graphics and the subject/patient brain is easily confirmed. The program is the first easy-to-use software that contains these specific features and is available for interested researchers with a background in lesion analysis.

Adult↗