Biomedical subjects

J Szumowski

Publications and source records attributed to J Szumowski.

At least 19 recordsLinked to original sources

PubMed2005

Temporal lobe magnetic resonance spectroscopic imaging following selective amygdalohippocampectomy for treatment-resistant epilepsy.

OBJECTIVES: Magnetic resonance spectroscopic imaging (MRSI) may show circumscribed or extensive decreased brain N-acetyl aspartate (NAA)/creatine and phosphocreatine (Cr) in epilepsy patients. We compared temporal lobe MRSI in patients seizure-free (SzF) or with persistent seizures (PSz) following selective amygdalohippocampectomy (SAH) for medically intractable mesial temporal lobe epilepsy (mTLE). We hypothesized that PSz patients had more extensive temporal lobe metabolite abnormalities than SzF patients. MATERIALS AND METHODS: MRSI was used to study six regions of interest (ROI) in the bilateral medial and lateral temporal lobes in 14 mTLE patients following SAH and 11 controls. RESULTS: PSz patients had more temporal lobe ROI with abnormally low NAA/Cr than SzF patients, including the unoperated hippocampus and ipsilateral lateral temporal lobe. CONCLUSION: Postoperative temporal lobe MRSI abnormalities are more extensive if surgical outcome following SAH is poor. MRSI may be a useful tool to improve selection of appropriate candidates for SAH by identifying patients requiring more intensive investigation prior to epilepsy surgery. Future prospective studies are needed to evaluate the utility of MRSI, a predictor of successful outcome following SAH.

Adult↗

PubMed1998

Aortic and lower-extremity arterial disease: evaluation with MR angiography versus conventional angiography.

PURPOSE: To compare magnetic resonance (MR) angiography with conventional angiography in evaluation of the aorta and lower-extremity arterial system. MATERIALS AND METHODS: Fifty-seven patients were evaluated with femoral conventional and MR angiography. Iliac artery segments were evaluated with two-dimensional and contrast material-enhanced three-dimensional time-of-flight MR angiography. Infrainguinal regions were evaluated with two-dimensional time-of-flight MR angiography with a dedicated lower-extremity coil. Arteries depicted on femoral images were separately interpreted as 20 anatomic segments. Disease classification included normal to moderate disease (0%-50% stenosis), severe stenosis (> 50% stenosis), diffuse disease (more than one severe stenosis), and occlusion. Four readers interpreted the images and rendered treatment recommendations. RESULTS: Substantial to almost perfect interobserver agreement (kappa, 0.66-1.00) was achieved in most cases for MR angiogram interpretation. The three most experienced readers achieved substantial to almost perfect intraobserver agreement (kappa, 0.61-1.00) between conventional and MR angiogram interpretation in most cases. Among three readers, moderate agreement (kappa, 0.43-0.53) was found between treatment recommendations based on conventional versus MR angiographic findings; for the most experienced reader, this agreement was almost perfect (kappa, 0.90). CONCLUSION: For experienced readers, there was substantial to almost perfect agreement between conventional and MR angiographic image interpretations of the aorta and lower-extremity arterial system.

Aged↗

PubMed1997

Two-point Dixon technique for water-fat signal decomposition with B0 inhomogeneity correction.

To separate water and lipid resonance signals by phase-sensitive MRI, a two-point Dixon (2PD) reconstruction is presented in which phase-unwrapping is used to obtain an inhomogeneity map based on only in-phase and out-of-phase image data. Two relaxation-weighted images, a "water image" and a "fat image," representing a two-resonance peak model of proton density, are output. The method is designed for T1- or density-weighted spin-echo imaging; a double-echo scheme is more appropriate for T2-weighted spin-echo imaging. The technique is more time-efficient for clinical fat-water imaging than 3PD schemes, while still correcting for field inhomogeneity.

Breast↗

PubMed1997

Alteration of ascending thoracic aorta compliance after treatment with menotropin.

OBJECTIVE: Our purpose was to determine whether aortic size and compliance are altered by an exogenously induced rise in estrogen. STUDY DESIGN: Magnetic resonance imaging was used to determine the aortic cross-sectional area/aortic pressure relationship in nine premenopausal women before and after menotropin therapy. Simultaneous electrocardiograms, carotid pulse tracings, phonocardiograms, and brachial artery pressures were obtained before each magnetic resonance imaging acquisition. Ascending thoracic aorta cross-sectional area was obtained every 32 msec and aligned with brachial artery pressures extrapolated from the carotid pulse tracing, allowing construction of the ascending thoracic aorta cross-sectional area/aortic pressure relationships. Aortic cross-sectional area was normalized to body surface area, and the shifts in the position for the ascending thoracic aorta cross-sectional area/aortic pressure relationship were determined with use of analysis of covariance. RESULTS: Heart rate and aortic pressure were unchanged before and after menotropin treatment. Initial estradiol levels were < 20 pg/ml. After menotropin treatment (7.4 +/- 1.0 days) estradiol levels rose to 905 +/- 371 pg/ml (p < 0.0001). Ascending thoracic aorta cross-sectional area/body surface area was not significantly increased, adjusted y mean of 389 +/- 7 mm2/m2 before and 403 +/- 7 mm2/m2 after menotropin treatment (p < 0.24). The slope of the ascending aorta cross-sectional area/aortic pressure relationship, an index of aortic compliance, increased from 1.4 +/- 0.6 mm2/m2/mm Hg before to 1.7 +/- 0.6 mm2/m2/mm Hg after menotropin treatment (p < 0.001). CONCLUSION: In premenopausal women a short-term rise in estrogen induced by menotropin treatment is associated with an increase in aortic compliance. Aorta size is not significantly increased within this time frame.

Adult↗

PubMed1996

Coronal fat suppression fast spin echo images of the knee: evaluation of 202 patients with arthroscopic correlation.

We optimized fat-suppressed fast spin echo (FS-FSE) parameters for coronal imaging of the knee and then evaluated the technique in a clinical setting. Five volunteers and 12 patients were used to evaluate various repetition (TR), echo (TE), and echo train lengths (ETL). Then, 202 patients underwent both knee MR imaging using coronal plane FS-FSE and arthroscopy. The coronal FS-FSE images were compared with radial multiplanar gradient-recalled echo (MPGRE), axial T1-weighted SE, and parasagittal double echo SE images. Proton density images (2,000/19) with an ETL of 2 best depicted the menisci, ligaments, and capsules. The conspicuity of osteochondral abnormalities depicted by the coronal FS-FSE imaging was significantly higher than for axial T1-weighted SE (p < .003) and parasagittal echo SE images (p < .003). The accuracy of the coronal FS-FSE imaging for medial and lateral meniscal tears was 91.6% and 87.6%, respectively. Combined imaging interpretation of the coronal FS-FSE, axial T1-weighted SE, and radial MPGRE imaging improved the accuracy for meniscal tears slightly over any sequence used alone, but the difference was not statistically significant. Fourteen capsular injuries were demonstrated by the coronal FS-FSE imaging. FS-FSE imaging in the coronal plane is a useful complementary sequence in MR examinations of the knee for the evaluation of meniscal tears, capsular injuries, and osteochondral abnormalities.

Adolescent↗

PubMed1995

Double-echo three-point-Dixon method for fat suppression MRI.

A double-echo two-excitation pulse sequence encoding fat and water signals for a phase-sensitive three-point Dixon-type analysis (DE-3PD) was developed and implemented on a 1.5 T MR imager. Data processing was performed using a previously developed two-dimensional (2D) region-growing algorithm, adapted to use double-echo data. Density-, T1-, and T2-weighted fat suppression images were obtained from six volunteers using the new fat suppression method. The images were compared with corresponding images obtained using frequency-selective excitation fat suppression (FATSAT) and a single-echo three-point-Dixon method (SE-3PD). The results demonstrate that the DE-3PD sequence shortens the imaging time by one-third compared with the SE-3PD method, without loss in image quality. The data also show that a 2D region-growing algorithm effectively unwraps the phase of DE-3PD data sets, and that results of DE-3PD fat signal suppression are consistently better than those obtained using a standard FATSAT method. The authors conclude that the double-echo sequence provides density-, T1-, and T2-weighted images that appear to be promising for routine clinical applications.

Abdomen↗

PubMed1995

Evaluation of the combination of vinblastine and quinidine in patients with metastatic renal cell carcinoma. A phase I study.

Quinidine is known to inhibit p-glycoprotein and enhance the activity of vinblastine against cultured renal carcinoma cells. We have combined quinidine and vinblastine in a Phase I trial in patients with metastatic renal cell carcinoma. Twenty-three patients were entered. Prior treatment included nephrectomy (15 patients), radiation (1 patient) and interferons (8 patients). Cohorts of patients were treated at one of three quinidine dose levels (100, 200, and 400 mg); one patient received 300 mg. Quinidine was given orally 4 times daily starting 3 days prior to the first dose of vinblastine of 5 mg/m2 intravenously given once a week. Hematologic parameters, EKG, and quinidine levels were monitored weekly. Mean quinidine levels in each dose tier were 1.58, 2.59, and 4.24 micrograms/ml, respectively. The dose-limiting toxicity was leukopenia, which necessitated dose interruptions in 16 patients. The mean nadir WBC count (x 10(9)/L) was 3.47, 2.3, and 1.73 in each dose tier, respectively. Corresponding values for the mean maximum decrease in WBC count from baseline were 3.85, 5.86, and 6.53, respectively. There was a trend for leukopenia to become more severe with increasing doses of quinidine. Other toxicities included mild nausea and vomiting in all patients, and hypotension and paralytic ileus in one patient each. No cardiac toxicity was observed. One patient had a complete remission and 4 patients had stable disease. We conclude that quinidine and vinblastine may be administered together safely in a clinical setting, with leukopenia being dose-limiting. Further studies are needed to determine any therapeutic advantage over vinblastine alone.

Adult↗

PubMed1995

Rotator cuff tendon tears: evaluation with fat-suppressed MR imaging with arthroscopic correlation in 100 patients.

PURPOSE: To evaluate the diagnostic accuracy of fat-suppressed magnetic resonance (MR) imaging of rotator cuff tears in a large symptomatic population. MATERIALS AND METHODS: One hundred patients underwent both MR imaging and arthroscopy of the shoulder. Ninety-two patients underwent fat-suppressed conventional spin-echo MR imaging (repetition time msec/echo time msec = 2,500/20, 60), and eight patients underwent fat-suppressed, fast spin-echo MR imaging (2,000/80). RESULTS: With data combined for complete and partial tears of the rotator cuff (n = 31), MR imaging had an accuracy of 93%; sensitivity, 84%; and specificity, 97%. Seventeen of 20 complete tears and nine of 11 partial tears were properly identified with MR imaging. Two partial tears were not detected and three complete tears were incorrectly called partial tears at MR imaging. Of two false-positive MR imaging findings, one was called a complete tear and the other, a partial tear. CONCLUSION: Fat-suppressed MR imaging has high diagnostic accuracy in evaluating tears of the rotator cuff tendon.

Arthroscopy↗

PubMed1995

Lower extremities: MR angiography with a unilateral telescopic phased-array coil.

In a comparison of conventional and magnetic resonance (MR) angiography of the lower extremities, MR imaging was performed with extremity and body coils and a unilateral six-coil telescopic phased-array coil. In one of seven volunteers, average signal-to-noise ratio was 140% higher with the latter (p < .01), only three of five stations were necessary, and examination time was decreased 50%. In the four patients, correlation in findings was 100%.

Adult↗

PubMed1995

Detection of discrete white matter lesions after irreversible compression of MR images.

PURPOSE: To validate the use of techniques of irreversible compression of images, which can be performed using a block-based discrete cosine transform technique as defined by the Joint Photographic Experts Group, before they can be used in clinical applications, by evaluating the effect of compression on the ability of observers to detect discrete white matter lesions on MR images of the brain. METHODS: Sixty T2- and intermediate-weighted spin-echo images were compressed with varying degrees of coefficient quantization with compression ratios from 1:1 to more than 40:1, randomized, and evaluated by three observers blinded to the degree of compression. RESULTS: No significant difference in the number of lesions detected was apparent until compression ratios reached 40:1, despite a significant subjective loss in perceived image quality at 20:1. Only small (< or = 5 mm) lesions were missed at the highest degree of compression. No significant differences were observed in the detection of confluent periventricular white matter disease at any degree of compression tested. CONCLUSIONS: The use of high degrees of irreversible compression of MR images may be acceptable for diagnostic tasks.

Brain↗

PubMed1995

Differential permeability and quantitative MR imaging of a human lung carcinoma brain xenograft in the nude rat.

This study characterized agent differential permeability, three-dimensional tumor volume, and survival in an LX-1 human small cell lung carcinoma intracerebral xenograft model in the nude rat. The percent accessible tissue space (distribution volume) and the permeability x capillary surface product for aminoisobutyric acid (M(r) 103), methotrexate (M(r) 454), dextran 10 (M(r) 10,000), and dextran 70 (M(r) 70,000) were measured between 8 and 16 days after inoculation of tumor. Magnetic resonance imaging and histology were used to quantitate intracerebral tumor volume (mm3). Accessible tissue space (ml/g) and permeability x capillary surface product in intracranial tumor, surrounding brain, and subcutaneous tumor decreased with increasing molecular weight of the agent, regardless of the number of days after inoculation. Accessible tissue space in intracranial tumor increased between 8 and 16 days for all agents except dextran 70. There was little change in the subcutaneous tumor or other tissues with time. Tumor volume calculations from imaging studies correlated with volumetric measurements from histological sections (r2 = 98.5%) and illustrated natural tumor progression (9 to 225 mm3). These results provide a basis for therapeutic design based on differential permeability of specific agents and the ability to quantitatively measure brain tumor volume for accessing tumor response.

Animals↗

PubMed1994

MR imaging of prostate cancer with an endorectal surface coil technique: correlation with whole-mount specimens.

PURPOSE: To evaluate the diagnostic accuracy of magnetic resonance (MR) imaging in staging prostate cancer with an endorectal surface coil technique. MATERIALS AND METHODS: The authors prospectively evaluated MR images obtained with an endorectal surface coil from 70 consecutive patients with known prostate cancer. Gadopentetate dimeglumine was administered to 40 patients. Multiple sequences were used, including conventional and fast spin echo, with and without fat suppression. The readers were blinded to the MR findings unless bone or nodal metastasis was present. MR images were compared with whole-mount sections. RESULTS: The prospective staging accuracy for MR imaging was 51% (36 of 70 patients). Stage B disease was present in 27 patients (38%), stage C in 42 (60%), and stage D in one (1%). The retrospective staging accuracy was 67% (47 of 70 patients). Of the 42 patients with stage C disease, positive surgical margins were present in 36 (85%). Gadopentetate dimeglumine did not help detect or stage tumors. CONCLUSION: Further studies must be performed to determine the role of endorectal coil MR imaging in the staging of prostate cancer.

Aged↗

PubMed1994

Phase unwrapping in the three-point Dixon method for fat suppression MR imaging.

PURPOSE: TO present an algorithm for performing phase unwrapping for fat and water signal separation in the three-point Dixon (3PD) method of magnetic resonance (MR) imaging. MATERIALS AND METHODS: The algorithm is based on a two-dimensional region-growing approach, which tracks phase evolution in 3PD images and unwraps the phase when a 2 pi jump is detected. The unwrapped phase data are consecutively used to calculate fat and water signal components on a per-pixel basis. The method was tested in eight volunteers. RESULTS: The algorithm creates four output images: standard spin-echo, fat suppression, water suppression, and phase map images. This method corrects for the effects of magnetic field inhomogeneities and provides spatially uniform fat signal suppression superior to that achievable with the standard method. CONCLUSION: This method of 3PD data reconstruction appears to be promising for routine application of fat suppression MR imaging in a clinical setting.

Humans↗

PubMed1994

Chondromalacia patellae: fat-suppressed MR imaging.

PURPOSE: To evaluate the accuracy of fat-suppressed magnetic resonance (MR) imaging in diagnosing chondromalacia patellae. MATERIALS AND METHODS: Seventy-one patients underwent fat-suppressed MR imaging and arthroscopy of the patellofemoral compartment. Findings were classified as early or advanced chondromalacia or as normal and were correlated with arthroscopic findings. RESULTS: Early and advanced stages of chondromalacia patellae were reliably detected, with positive predictive values of 85% and 92%, respectively. Specificity in early stages was 94% and in late stages was 98%. However, the overall accuracies did not differ substantially from those reported in studies that did not use fat-suppressed imaging. CONCLUSION: Axial, fat-suppressed MR imaging accurately depicts changes caused by chondromalacia patellae. Early stages can be seen as intrasubstance changes of increased signal intensity. Results of this study suggest a high degree of specificity in excluding both early and advanced changes.

Adolescent↗

PubMed1994

Delivery of virus-sized iron oxide particles to rodent CNS neurons.

Delivery of viral particles to the brain is limited by the volume of distribution that can be obtained. Additionally, there is currently no way to non-invasively monitor the distribution of virus following delivery to the central nervous system (CNS). To examine the delivery of virus-sized particles across the blood-brain barrier (BBB), dextran coated, superparamagnetic monocrystalline iron oxide particles, with a hydrodynamic diameter of 20 +/- 4 nm, were delivered to rat brain by direct intracerebral inoculation or by osmotic BBB disruption with hypertonic mannitol. Delivery of these particles was documented by magnetic resonance (MR) imaging and, unexpectedly, neuronal uptake was demonstrated by histochemical staining. Electron microscopy (EM) confirmed iron particle delivery across the capillary basement membrane and localization within CNS parenchymal cells following administration with BBB disruption. This is the first histologic and ultrastructural documentation of the delivery of particles the size of virions across the blood-brain barrier. Additionally, these dextran-coated, iron oxide particles may be useful, in and of themselves, as vectors for diagnostic and/or therapeutic interventions directed at the CNS.

Animals↗

PubMed1994

Quantitative contrast-enhanced MR imaging of the optic nerve.

During the acute stages of optic neuritis damage to the blood-optic nerve barrier can be detected using i.v. paramagnetic contrast-enhanced MR imaging. Quantification of the enhancement pattern of the optic nerve, intraorbital fat and muscle was determined in 15 normal subjects using 3 fat-suppression MR imaging methods: T1-weighted spin-echo and spoiled gradient-echo sequences preceded by a fat-frequency selective pulse (FATSAT+SE and FATSAT+SPGR, respectively) and a pulse sequence combining CHOPPER fat suppression with a fat-frequency selective preparation pulse (HYBRID). Pre- and postcontrast-enhanced studies were acquired for FATSAT+SE and FATSAT+SPGR. There was no significant enhancement of the optic nerve by either method (mean increase of 0.96% and 5.3%, respectively), while there was significant enhancement in muscle (mean 118.2% and 108.2%, respectively; p < 0.005) and fat (mean increase of 13% and 37%, respectively; p < 0.05). Postcontrast optic nerve/muscle signal intensity ratios (mean, SD) were 0.51 (0.07), 0.58 (0.05) and 0.75 (0.05) for FATSAT+SE, FATSAT+SPGR and HYBRID, respectively. These results suggest a practical methodology and range of values for normal signal intensity increases and ratios of tissue signal that can be used as objective measures of optic neuritis for natural history studies and treatment trials.

Adipose Tissue↗

PubMed1993

Femoral MR angiography versus conventional angiography: preliminary results.

PURPOSE: To develop a bilateral femoral magnetic resonance (MR) angiographic examination that would include the aortic bifurcation to the ankle. MATERIALS AND METHODS: Thirty-seven patients underwent conventional angiography and the bilateral femoral MR angiographic examination. Two-dimensional time-of-flight angiography was used for all studies. RESULTS: The femoral MR angiogram could have replaced the conventional angiogram in 57% of patients (21 of 37). In 43% of patients (16 of 37), the femoral MR angiogram could not have replaced the conventional angiogram. Reasons for diagnostic failure with femoral MR angiography included artifact from vascular clips (n = 8) or prosthetic joints (n = 3), overlooked distal aortic stenosis (n = 1), and suboptimal definition of vessels (usually trifurcation vessels) owing to various causes (n = 8). Seven of the patients in this group had bypass grafts. CONCLUSION: Some of the current limitations of femoral MR angiography could be avoided by supplemental duplex sonography around prostheses and vascular clips. The other limitations will require advances in MR imaging techniques.

Aged↗

PubMed1992

Proton (fat/water) chemical shift imaging in medical magnetic resonance imaging. Current status.

Fat/water CSI has recently been transformed from an experimental method to a routine clinical MRI approach, particularly for evaluating paramagnetic contrast enhancement in fat-rich regions and as a piggyback method for decreasing MRI artifacts, such as in MR angiographic and echo-planar imaging. The full and appropriate use of CSI in medical MRI requires consideration of the factors and strategies outlined in this review. As the commercial implementation of fat/water CSI continues, we can expect further applications in clinical and experimental studies. For example, in imaging areas where MRI has been of limited efficacy, such as pancreas imaging, skin microimaging and vascular imaging, there are indications that these CSI methods may have practical importance. It seems reasonable to project that for high chemically specific detail, medical fat/water CSI will ultimately be supplanted by SI methods, and certainly by localized spectroscopy. The power of the fat/water CSI method remains its extremely high anatomic resolution, which cannot be achieved by current spectroscopy or SI methods. The fat/water CSI methods provide a means for clinically relevant MRI with more accurate and chemically specific information. Expansion of these methods into three-dimensional and fast imaging formats is already taking place at or near the commercial level. For example, the feasibility of combining echo-planar imaging and CSI methods has already been demonstrated. Methods based on the phase-contrast techniques, such as susceptibility mapping and interferometry, are additional implementations that can provide detailed and more specific information in a high anatomic detail format.

Adipose Tissue↗