Search PubMed⌕ Search

Biomedical subjects

L Vlahos

Publications and source records attributed to L Vlahos.

At least 55 records · Page 3Linked to original sources
PubMed1998

Fetal dose evaluation during breast cancer radiotherapy.

PURPOSE: The aim of the work was to estimate the radiation dose delivered to the fetus in a pregnant patient irradiated for breast cancer. METHODS AND MATERIALS: A 45-year woman was treated for left breast cancer using a 6 MV photon beam with two isocentric opposing tangential unwedged fields. Daily dose was 2.3 Gy at 95% isodose line given by two fields/day, 5 days/week. A total dose of 46 Gy was given in 20 fractions over a 4-week period. Pregnancy confirmed during the second therapeutic week. Treatment lasted between the second and sixth gestation week. Radiation dose to fetus was estimated from in vivo and phantom measurements using thermoluminescence dosimeters and an ionization chamber. In vivo measurements were performed by inserting either a catheter with TL dosimeters or ionization chamber into the patient's rectum. Phantom measurements were performed by simulating the treatment conditions on an anthropomorphic phantom. RESULTS: TLD measurements (in vivo and phantom) revealed fetal dose to be 0.085% of the tumor dose, corresponding to a cumulative fetal dose of 3.9 cGy for the entire treatment of 46 Gy. Chamber measurements (in vivo and phantom) revealed a fetal dose less than the TLD result: 0.079 and 0.083% of the tumor dose corresponding to cumulative fetal dose of 3.6 cGy and 3.8 cGy for in vivo and phantom measurement, respectively. CONCLUSIONS: It was concluded that the cumulative dose delivered to the unshielded fetus was 3.9 cGy for a 46 Gy total tumor dose. The estimated fetal dose is low compared to the total tumor dose given due to the early stage of pregnancy, the large distance between fundus-radiation field, and the fact that no wedges and/or lead blocks were used. No deterministic biological effects of radiation on the live-born embryo are expected. The lifetime risk for radiation-induced fatal cancer is higher than the normal incidence, but is considered as inconsequential.

Breast Neoplasms↗
PubMed1998

Langerhans cell histiocytosis with involvement of the pons: case report.

Central nervous system involvement is uncommon in Langerhans cell histiocytosis. The suprasellar region is more frequently affected. There have been few reports of involvement of the brain parenchyma shown on CT or MRI. We present a case of involvement of the pons, showing marked contrast enhancement on MRI.

Central Nervous System Diseases↗
PubMed1998

Abdominal Takayasu's arteritis: imaging with color duplex sonography.

Takayasu's arteritis is a inflammatory process of unknown etiology affecting mainly the thoracic and abdominal aorta and producing steno-occlusive findings of various degrees in different sites. We present a case of Takayasu's disease in a young woman, studied by color duplex sonography and verified by angiography.

Adolescent↗
PubMed1998

Myocardial iron deposition in beta-thalassemia studied by magnetic resonance imaging.

Myocardial iron deposition is a common finding in beta-thalassemia. The iron content of the myocardium was assessed using the T2 relaxation time of the heart. The T2 relaxation time of the liver and skeletal muscle was also assessed in order to study the relation of iron deposition between heart, liver and skeletal muscle. ECG gated spin echo images were obtained from thirty-eight consecutive adult thalassemic patients examined in an outpatient clinic, aged (x +/- SD) 25 +/- 6 years, using a 0.5 T system. Patients were divided into groups A and B, according to their average serum ferritin levels of the preceding five years (> or < 2000 ng/ml). Results were compared with nine controls, aged 24 +/- 7 years. Heart T2 relaxation time in the control group (x +/- SD) (48.3 +/- 5.5 msec) was higher compared to group A (28.4 +/- 6.7 msec, p < 0.001) but not to group B (43.4 +/- 7.4 msec). The T2 relaxation time of the heart correlated positively with the T2 relaxation time of the liver (r = 0.68, p < 0.001) and negatively with ferritin levels (r = -0.67, p < 0.001). There was no correlation with the T2 relaxation time of skeletal muscle. This study indicates that regularly transfused beta-thalassemia patients may present with a broad variation of heart iron deposition which, however, is related to serum ferritin levels.

Adult↗
PubMed1998

Radiation therapy alone for growth hormone-producing pituitary adenomas.

We present our experience in the treatment of growth hormone (GH)-producing pituitary adenomas using irradiation alone. Between 1983 and 1991, 21 patients suffering from GH-secreting pituitary adenomas were treated with radiotherapy alone. Two bilateral opposing coaxial fields were used in 10 patients and in the remaining 11 a third frontovertex field was added. Treatment was given in 1.8-2 Gy daily fractions and total dose ranged between 45 and 54 Gy. Treatment was given using a cobalt unit. Four patients treated with somatostatin prior to and 14 patients treated after the end of radiotherapy experienced symptom relief for 6-28 weeks. The 5-year actuarial rate of disease control was 72%. Five out of six failed patients had macroadenomas. Hypopituitarism was observed in 5/21 (24%) patients. Whereas RT alone is effective in the treatment of microadenomas, this is not true for large infiltrative macroadenomas.

Adult↗
PubMed1998

Management of renal angiomyolipoma by selective arterial embolization.

4 Patients with renal angiomyolipomas are presented. One of them had tuberous sclerosis with synchronous bilateral tumors. All the patients were symptomatic, 2 of them with retroperitoneal hemorrhage. In all patients selective arterial embolization was performed. Permanent control of the symptoms was successful in 2 patients. In 1 patient temporary resolution of the symptoms was observed, and a second embolization was required. Retroperitoneal bleeding in 1 patient continued and nephrectomy was undertaken.

Adolescent↗
PubMed1997

T2 relaxation times of irradiated vertebral bone marrow in patients with seminoma.

Our purpose was to demonstrate the effects of localized radiotherapy on lumbar vertebral bone marrow with the use of quantitative MRI with measurements of T2 relaxation times. Ten patients with early stage testicular seminoma with a history of radiation therapy to a "dog-leg" field including the lumbar vertebrae underwent MR imaging of their lumbar spine using a 0.5 Tesla magnet. Five healthy subjects and two nonirradiated patients were imaged as well. The intervals from the beginning of radiotherapy to MRI examination varied from 1.5 to 52 months, and the radiation dose ranged from 3000-4200 cGy. The T2 relaxation times of the lumbar vertebral bone marrow and subcutaneous fat were calculated for each subject. Postirradiation bone marrow in irradiated seminoma patients exhibited significantly longer T2 relaxation times than nonirradiated bone marrow in controls (71.1 vs. 63.6 ms, p = 0.047, t-test). The differences between the T2 relaxation times of bone marrow and subcutaneous fat for each subject allowed for even better differentiation between irradiated patients and controls (10.4 vs. 0.4 ms, p = 0.0004, t-test). Postirradiation bone marrow had significantly longer T2 relaxation times than subcutaneous fat in irradiated patients (N = 10, 71.1 vs. 60.7 ms, p = 0.00009, t-test), while nonirradiated bone marrow had T2 relaxation times not statistically different from subcutaneous fat in nonirradiated subjects (N = 7, 63.6 vs. 63.2 ms). Measurements of T2 relaxation times of bone marrow enabled us to differentiate between irradiated seminoma patients and controls. Postirradiation bone marrow undergoes late radiation effects resulting in longer T2 relaxation times than nonirradiated bone marrow and subcutaneous fat.

Adipose Tissue↗
PubMed1997

Receptor scintigraphy of non-neuroendocrine cancers with In-111 pentetreotide.

Somatostatin receptors (SR) are surface markers characterizing not only APUDomas associated with neuroendocrine identities but also malignancies without neuroendocrine expression. Recently, the somatostatin analog pentetreotide was labeled with In-111 (OctreoScan 111, Mallinckrodt Medical BV, Petten, Holland) and introduced for the in vivo visualization in man of SR-positive tissues. In the present report, SR-specific scintigraphy is evaluated as a clinical tool for tissue characterization in correlation with histological and radiological examinations. Scintigraphy was focused and performed in cancer types without neuroendocrine tissue expression such as brain (n = 6) and breast tumors (n = 9) and lymphomas (n = 5). Scintigraphy was performed for comparison at 6 and 22 h after i.v. application of 111 MBq (3 mCi) of In-111-Pentetreotide. In the breast cancer group, the primary tumor was visualized in all 9 women as well as in all 4 cases with palpable axillary lymph nodes. Three women with a negative axillary node scan and impalpable nodes had positive biopsy. In two cases, mediastinal lymph node involvement was observed. So far the role of SR-positive breast cancer (BC) scans remains unknown. It is tempting to speculate that in resected women who are histologically and scintigraphically SR positive, it might be of value in the early detection of symptom-free recurrences. High densities of SR were present within both meningiomas, the high-grade astrocytoma and the craniopharyngioma. Differentiation of low- and high-grade astrocytomas could not be successfully achieved because both grades showed intense radioactivity uptake, even though high-grade tumors lack SR. The latter might be due to the damaged blood-brain barrier and the poor radioactivity washout observed in high-grade astrocytomas. All five lymphomas could be detected due to the presence of activated lymphocytes and macrophages that express SR at a sufficient density. In conclusion, SR scintigraphy in non-neuroendocrine malignancies does not seem to be reliable for an initial tumor staging but rather more suitable for a tissue characterization and extremely useful for monitoring changes of SR expression after treatment.

Adolescent↗
PubMed1997

Radiographic determination of total lung capacity in patients with pneumonectomy.

To determine whether total lung capacity (TLC) can be measured from plain chest radiographs in patients with pneumonectomy, we examined 20 such patients (17 male, 3 female) who had pneumonectomy for lung carcinoma. In 16 patients the right lung was preserved, and in 4 the left. The TLC was measured with the helium dilution method and by planimetry of the anterior and lateral projections of the lung on chest radiographs, summing the anterior and lateral projected areas of the lung to a single value, S. The correlation between S and TLC by helium gas dilution was r = 0.95. Linear fit of TLC to S explained 99.5% of the variance in TLC, with the equation. The side resected did not influence the predictive value (p < 0.001). The interquartile range of the residual error was +/-130 ml, and standard error was 64 ml. Therefore in patients with pneumonectomy, TLC of the preserved lung may be estimated within +/-130 ml by planimetry of the anterior and lateral chest radiographs.

Aged↗
PubMed1996

MRI of nasopharyngeal carcinoma metastatic to the cerebellopontine angle.

In patients with nasopharyngeal carcinoma, intracranial spread may occur via direct extension from the base of the skull or via perineural spread. Perineural spread usually affects branches of the trigeminal nerve. We describe two patients with recurrent nasopharyngeal carcinoma, who presented with a solitary mass in the cerebellopontine angle without associated bony destruction. MRI findings mimicked those of acoustic schwannoma. The imaging findings and possible pathways of spread are discussed.

Adult↗
PubMed1996

Combined teletherapy and intracavitary brachytherapy boost for the treatment of nasopharyngeal carcinoma.

For the non-metastatic nasopharyngeal carcinoma, external beam radiation therapy (median dose 64 Gy) and a boost of intracavitary irradiation (ICRT) has been given. Caesium-137 pellets of 40 mCi were used at a dose rate of 3-3.5 Gy/h, 1 cm from the sources. The median dose was 8.5 Gy. Overall 5-year actuarial survival for the 48 studied patients was 60.4% and LRFS was 64%. The procedure was well tolerated by our patients.

Brachytherapy↗
PubMed1996

Ischemia of spinal cord following elective operative procedures of the infrarenal abdominal aorta.

OBJECTIVE: Ischemia of the spinal cord following procedures of the infrarenal abdominal aorta and the iliac arteries due to aneurysmatic or occlusive disease. DESIGN: Retrospective study, duration of follow up: two years. SETTINGS: Vascular Department of the 2nd Surgical Clinic of the University of Athens, Medical School. PATIENTS: 1,112 operative procedures to the infrarenal abdominal aorta and iliac arteries, carried out from January 1, 1976 to June 30, 1994; 665 cases were aneurysms, electively operated, to which a tube graft was placed in 390 and a bifurcated graft in the remaining 265. Similarly 457 bifurcated prostheses were placed due to stenotic disease. INTERVENTIONS: Aneurysmectomy, graft insertion. MEASURES: Death, severe disability. RESULTS: Ischemic damage to the spinal cord was noted in two cases postoperatively. The first case following placement of bifurcated prosthesis due to high occlusion of the abdominal aorta and the second case following resection of an aneurysm and placement of a tube graft. One of the patients passed away on the 43rd postoperative day, and the other 18 months after was able to stand but, however, could not walk easily without the help of another person. CONCLUSIONS: The complication seems to be multicausal, carrying a bad prognosis and cannot be foreseen. The stable hemodynamic condition of the patient during the operative and postoperative period with revascularisation of at least one hypogastric artery, reduces the time of aortic occlusion and securing collateral circulation might reduce these complications. Also preopeorative angiography of the spinal cord with more sophisticated techniques, might constitute the most reliable prognosis in the future.

Aged↗
PubMed1995

MRI in the investigation of patients with myelopathy thought to be due to multiple sclerosis.

The role of cerebral and spinal cord MRI was investigated in 65 patients with myelopathy suspected of having demyelinating disease. Cerebral MRI demonstrated lesions compatible with demyelination in 80% and spinal cord MRI in 68.6%. In 28.5% of our patients brain lesions were present with normal spinal cord images, but in 17% spinal cord lesions were depicted with a normal brain MRI. The combination of the two examinations demonstrated lesions in 97% of the patients. The frequency of coexistent cerebral lesions in patients with spinal cord lesions was over 85% in patients with chronic disease but only 28.5% in patients with acute myelitis.

Adolescent↗
PubMed1995

Value of Gd-DTPA-enhanced MR imaging of the labyrinth in patients with sudden hearing loss.

Recent reports describe labyrinthine enhancement on MRI as a highly specific sign of labyrinthine disease. This paper reports 44 patients with unilateral sensorineural hearing loss (SNHL) and laboratory evidence of cochlear damage investigated with Gd-enhanced MR imaging. Enhancement of the cochlea was observed in only one patient with a lesion at the fundus of the internal auditory canal (IAC) that extended into the cochlea after Gd-DTPA administration. In one more patient, MR imaging demonstrated large vestibular aqueducts as underlying cause for his hearing loss, but no enhancement of the labyrinth was observed. No abnormal signal intensity on precontrast MR scans nor pathologic enhancement of the membranous labyrinth were identified in the other 42 patients. Gd-enhanced MR imaging appears to be insensitive in demonstrating labyrinthine disease and normal examination findings in a patient with sudden SNHL cannot exclude damage at the cochlear level.

Adolescent↗
PubMed1994

A feasibility study of partially accelerated radiotherapy for invasive bladder cancer.

Thirty-nine patients with histologically confirmed invasive bladder carcinoma (T2-3, N0, M0) were treated with a partially accelerated radiotherapy scheme. After 40 Gy/4 weeks of conventional fractionation we have accelerated the treatment in the last week giving two daily fractions of 2 Gy each, 4-6 h apart in the bladder only. Although the follow-up of some of the patients is not very long our results indicate that this relatively short radiotherapeutic scheme is feasible, convenient and probably safe for patients living in remote areas.

Aged↗