Biomedical subjects

P S Palka

Publications and source records attributed to P S Palka.

5 recordsLinked to original sources

PubMed1996

Radiation-induced changes in the central nervous system and head and neck.

Radiation therapy of the brain, neck, and spine can be associated with radiation-induced changes that are increasingly evident radiologically. These changes affect the central nervous system (focal necrosis, diffuse white matter injury, atrophy, mineralizing microangiopathy, telangiectasia, optic neuropathy, large vessel vasculopathy), bone (fatty replacement of marrow, osteoradionecrosis, sinus inflammation), and superficial and deep soft tissues and include neoplasia. Focal necrosis, which most commonly occurs at the treatment site, is seen at computed tomography (CT) and magnetic resonance (MR) imaging as a ring-enhancing mass with edema and mass effect, findings similar to those of tumor recurrence. Diffuse white matter injury appears as hypoattenuating (at CT) or hyperintense (at MR imaging) small foci near the frontal or occipital horns or as a confluent band extending from the ventricles to the corticomedullary junction. Fatty replacement of marrow is the most common osseous complication seen on MR images. Osteoradionecrosis, which occurs most often in the mandible, appears as a focal lytic area at CT and with abnormal marrow signal and cortical destruction at MR imaging. The most common changes in the superficial soft tissues of the head and neck, edema and fibrosis, are seen radiologically as skin thickening and increased soft-tissue attenuation with stranding of subcutaneous fat. Meningioma, the most common radiation-induced CNS tumor, can be distinguished from spontaneous meningiomas on the basis of clinical characteristics (eg, presence of focal alopecia and scalp atrophy).

Adolescent↗

PubMed1996

Magnetic resonance spectroscopy (MRS) in the evaluation of pediatric brain tumors, Part I: Introduction to MRS.

Magnetic resonance spectroscopy (MRS) provides a means to assess functional (metabolic activity) of the brain. It is now possible to perform MRS in a clinical setting with the use of an inexpensive software package called Proton Brain Exam/Single Voxel (PROBE/SV) developed by General Electric Medical System for use on their 1.5-T MR scanner. We have used PROBE for over a year and have found it to be useful in the evaluation of brain abnormalities. Most of our experience with MRS has been in the evaluation of children with brain tumors. In this first article of a two-part series, a simplified introduction to single-voxel MRS is presented, including: 1) the differences in the normal MRS spectra of the brains of infants, children, and adults demonstrating the variation in peaks of the common metabolities (N-acetylasparate, creatine, and choline); 2) the two types of MRS pulse sequences, stimulated echo acquisition mode (STEAM), a T1-weighted sequence, and point resolved spectroscopy (PRESS), a T2-weighted sequence; and 3) some of the factors that influence the production of diagnostic and nondiagnostic spectra. Part Two will report findings on the efficacy of MRS in children with brain tumors. With a basic understanding of MRS, the abnormal spectra in the diagnosis of brain tumors can be appreciated.

Adult↗

PubMed1996

Magnetic resonance spectroscopy (MRS) in the evaluation of pediatric brain tumors, Part II: Clinical analysis.

Over a 1-year period (1994-1995), 75 children with brain neoplasms were evaluated with a new automated magnetic resonance spectroscopy (MRS) software package called Proton Brain Exam/Single-Voxel (PROBE/SV) to determine the efficacy of this modality in children. The children ranged in age from newborn to 17 years and were comprised of 30 girls and 45 boys. The types of brain neoplasms consisted of 45 astrocytomas, 4 medulloblastomas, 2 ependymomas, 3 craniopharyngiomas, 3 germinomas, 1 pineoblastoma, 2 teratomas, 1 choroid plexus papilloma, 4 meningiomas, 2 astroblastomas, 3 rhabdoids, and 5 metastases from primary brain neoplasms. All children underwent magnetic resonance imaging (MRI) at the same setting as the MRS examination. The MRS examination was performed with the stimulated echo acquisition mode (STEAM) pulse sequence in all children, and occasionally the point resolved spectroscopy (PRESS) sequence also was used. Qualitative spectra were obtained in all children, and at times quantification data also were obtained. We found that our spectra over the brain neoplasms were consistent with the MRS findings of brain neoplasms in the literature. There was markedly elevated choline with markedly decreased or absent N-acetylasparate and at times elevated lactate and lipid peaks. In children with meningiomas, there was also an elevated alanine peak. We found MRS to be extremely useful in 1) characterizing a brain mass as a neoplasm, 2) differentiating radiation necrosis and radiation-induced meningiomas from the recurrent primary tumor, 3) following treatment response of the primary neoplasm, 4) differentiating residual or recurrent primary neoplasm from postsurgical changes, and 5) identifying inactive neoplasms or neoplasms in remission.

Adolescent↗

PubMed1995

MR and CT imaging patterns in post-varicella encephalitis.

The aim of the investigation was to determine the patterns of cerebral involvement on computed tomography (CT) and magnetic resonance (MR) imaging in post-varicella encephalitis. Four children between the ages of 2 and 11 years presented over a 5-year period with a diagnosis of post-varicella encephalitis. Their imaging studies and clinical data were reviewed retrospectively. The medical histories of all four children were noncontributory except for recent bouts of chickenpox 1 week to 3 months prior to hospitalization. Three children presented with parkinsonian manifestations. Bilateral, symmetric hypodense, nonenhancing basal ganglia lesions were found on CT. These areas showed nonenhancing low signal intensity on T1-weighted images and high signal intensity on T2-weighted images on MR. One child presented with diffuse, multiple gray and white matter lesions of similar imaging characteristics; some lesions, however, did enhance. This child had no gait disturbances. Post-varicella encephalitis can produce two patterns of dramatic CT and MR findings. With an appropriate history and clinical findings, varicella as a cause of bilateral basal ganglia or diffuse cerebral lesions can be differentiated from other possible etiologies which include trauma, anoxia, metabolic disorders and demyelinating diseases.

Chickenpox↗

PubMed1990

[Clinical and hemodynamic evaluation of 6-week treatment of pulmonary hypertension in chronic obstructive lung diseases (COLD) with low dose of prazosin].

The value of vasodilatatory treatment of pulmonary hypertension due to chronic obturative pulmonary disease (c.o.p.d.) is still controversial. However in patients with c.o.p.d. causal treatment as well as chronic domestic oxygen therapy have a wide range of limitations. Among vasodilator alpha-1 blockers show less vasodilator-related adverse effects, and as known from acute trials they exert a potent effect on pulmonary circulation in patients with pulmonary hypertension and c.o.p.d. Prazosin was studied in 11 patients (10 men, 1 women) aged 63 +/- 7 years with advanced c.o.p.d. (FVC 1.8 +/- 0.41, FEV1 0.99 +/- 0.55 l) (s) after their clinical stabilisation. In 4 of them prazosin was added to the maintenance dose of diuretics and digitalis. Subjective status, NYHA functional class, spirometric (FVC, FEV1) and gaseous (PaO2, PCO2) parameters, weight, systemic blood pressure, and heart rate were noted. During Swan-Ganz catheterization mean pulmonary artery pressure (MPAP), right ventricular end-diastolic pressure (RVEDP), pulmonary wedge pressure (PCWP), cardiac output (CO), systemic (SVR) and pulmonary (PVR) vascular resistance were measured. The acute trial with 1 mg prazosin taken orally was followed by 2- and 6-week of 3 mg prazosin treatment assessment. After a single dose of 1 mg prazosin there was a significant decrease in MPAP from 36 +/- 9 to 28 +/- 10 (p = 0.001) and 44% decrease in RVEDP (p = 0.05). CO increased by 16% (p = 0.01). The fall in PVR (30%, p = 0.01) exceeded that in SVR (17%, NS). No adverse effects were observed. During 2-week 3 mg a day prazosin therapy 2 patients were excluded following dyspnea and systemic hypotonia.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗