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Biomedical subjects

F Mut

Publications and source records attributed to F Mut.

12 recordsLinked to original sources
PubMed2000

Evaluation of ocular tumors with technetium-99m-MIBI: planar pinhole technique or SPECT?

OBJECTIVE: This study compares 2 imaging protocols, planar pinhole technique (PPHT) and SPECT, for evaluating ocular masses with 99mTc-MIBI. METHODS: Sixteen patients with ocular lesions were studied. Planar images were acquired 10 min after the injection of 740 MBq 99mTc-MIBI with an LFOV camera fitted with a pinhole collimator (5.0 mm). A SPECT study was performed immediately after the planar study, using a 360 degrees orbit, 64 steps, 20 s/stop, a 128 x 128 matrix, and a low-energy high-resolution (LEHR) collimator. Twelve lesions (9.5-18.0 mm) proved to be malignant: 8 primary tumors (ocular melanoma); 3 local relapses of different tumors of the conjunctiva; and 1 ocular metastasis from breast cancer. The remaining 4 lesions (10.0-16.0 mm) were benign: 1 inflammatory lesion; 1 benign intraocular calcification; and 2 naevi. RESULTS: SPECT images showed 11 of 12 malignant lesions (91.6%), whereas the planar technique demonstrated only 4 of the 12 lesions (33.3%). One false-positive result, the inflammatory lesion, was visualized by both techniques. The remaining benign lesions were not detected with either method. CONCLUSION: Technetium-99m-MIBI SPECT is a sensitive technique for detecting malignant ocular tumors. SPECT imaging is a better alternative to planar imaging for ocular tumors.

Adolescent↗
PubMed1999

Changes in the cerebral blood flow in postlingual cochlear implant users.

Five postlingually deaf patients (age range 28-58 years) with multichannel cochlear implants were examined with single photon emission tomography (SPECT) (triple-head rotating gamma camera). Changes in the regional cerebral blood flow (rCBF) after intravenous administration of technetium-99m ethyl cysteinate dimer (Tc-99m ECD) were assessed through a stimulation paradigm, consisting of: i) click stimuli (75 dB SPL) in the ear that was to be implanted, 2 weeks before surgery; ii) stimulation with the same click, one month after initial fitting; iii) stimulation with hearing sequential Spanish sentences one month after initial fitting. The results showed a significant increase in the rCBF in the primary left auditory area and in the right auditory cortex, in conditions ii) and iii). The rCBF also showed a significant asymmetrical increase in the frontal lobes when the patient was hearing sequential sentences (condition iii)) with asymmetrical distribution among patients. These results are discussed, principally the correlation between speech discrimination scores and the rCBF distribution in the frontal and temporal lobes.

Adult↗
PubMed1998

Scintigraphic evaluation of malignant melanoma lesions with Tc-99m tetrofosmin.

Two cases of malignant melanoma (primary and metastatic lesions) imaged with Tc-99m tetrofosmin are reported. One patient showed intense uptake in a primary skin lesion of the thorax, and the other patient had accumulation in skin, cerebellum, breast, and lymph node metastases. Like Tc-99m MIBI, Tc-99m tetrofosmin imaging may be of clinical relevance in the evaluation of suspicious skin lesions and in patients with known cutaneous malignant melanoma in the assessment of recurrent disease during follow-up evaluation.

Adult↗
PubMed1998

99Tc(m)-MIBI scanning of the thyroid gland in patients with markedly decreased pertechnetate uptake.

Diffusely reduced 99Tc(m)-pertechnetate uptake is a relatively infrequent but annoying finding that impairs evaluation of the thyroid gland. We studied 32 female patients aged 19-85 years with markedly reduced pertechnetate uptake. The following causes of reduced pertechnetate uptake were recognized: treatment with iodinated pharmaceuticals (n = 15), suppression therapy with T4 (n = 11), subacute thyroiditis (n = 5) and massive tumour replacement (n = 1). 99Tc(m)-MIBI thyroid scintigraphy was performed within 24 h of the pertechnetate study. The results were correlated with neck ultrasound, serum TSH (n = 25) and surgical findings in patients who had been operated on. The technique identified the following conditions: normally sized thyroids (n = 4), diffuse goitres (n = 8), multinodular goitres (n = 17) and solitary thyroid nodules (n = 3). Moreover, substernal goitres were identified in nine patients. This condition was confirmed at surgery in seven patients. Ultrasonography was concordant in 29 of 32 patients in terms of thyroid size and structure, but failed to demonstrate substernal thyroid tissue. Our results suggest that 99Tc(m)-MIBI scintigraphy may contribute to the diagnosis of thyroid pathology and treatment planning in patients with diffusely decreased 99Tc(m)-pertechnetate uptake.

Adult↗
PubMed1998

Detection of recurrent malignant melanoma with 99mTc-MIBI scintigraphy.

Initial reports suggest that 99mTc-methoxyisobutylisonitrile (MIBI) scanning may be of clinical value in staging patients with malignant melanoma. We carried out a study to evaluate the potential of this technique in the detection of recurrent disease. Whole-body 99mTC-MIBI scans were performed in 81 patients with a history of a surgically excised MM: 28 with known recurrent lesions and 53 during follow-up without evidence of disease. Images started 10 min post-injection, using a dose of 740 MBq. Diagnoses were confirmed by cytological/histological examination or at least one conventional imaging modality. Blinded interpretations of the MIBI scans were performed. Whole-body MIBI scanning correctly detected 68 (92%) of 74 metastatic lesions in the following sites: regional lymph nodes (n=23), non-regional lymph nodes (n=10), skin (n=16), brain/cerebellum (n=6), lung (n=8), bone (n=4) and breast (n=1). The technique failed to detect three subcutaneous regressive lesions (< 1 cm), one liver metastasis, one spleen metastasis and a case of multiple small lesions of the duodenal mucous membrane. In 14 patients the procedure detected previously unknown metastatic lesions. These results suggest that 99mTc-MIBI scanning is an effective imaging modality for whole-body screening of metastatic disease in malignant melanoma patients with the potential to influence treatment planning.

Adult↗
PubMed1996

Thyroid imaging with Tc-99m MIBI in patients with solitary cold single nodules on pertechnetate imaging.

Thyroid imaging was performed in 30 patients with the standard pertechnetate technique, as well as with Tc-99m MIBI using a double-phase acquisition protocol. All patients had normal thyroid function confirmed by hormone measurements and cold solitary thyroid nodules, which were evaluated by pertechnetate scanning. Tc-99m MIBI scans were reported as showing cold (N = 14), warm (N = 7), or hot (N = 9) nodules. Nodule classification was made according to fine needle aspiration biopsy findings in 20 patients. The remaining 10 proceeded to surgery and had histopathologic confirmation of their lesions. Although all cold nodules with Tc-99m MIBI were cystic, six of the warm nodules were benign lesions. No histologically proven benign nodule was hot with Tc-99m MIBI. Of the hot nodules, seven were suspicious for follicular carcinoma with fine needle aspiration biopsy (N = 3), or had histologically proven papillary carcinoma (N = 4). Delayed images in five of seven of these lesions showed nodular retention of the radiopharmaceutical. In conclusion, double-phase Tc-99m MIBI scanning of the thyroid gland could be helpful in the preoperative assessment of patients with cold solitary thyroid nodules in order to evaluate the malignancy probability of these lesions.

Adenocarcinoma, Follicular↗
PubMed1996

Scintigraphic detection of invasive cutaneous malignant melanoma with Tc-99m MIBI.

Malignant melanoma is a relatively uncommon cancer of increasing incidence. The authors report on two cases of malignant melanoma lesions (primary and lymph node metastasis) imaged with Tc-99m MIBI. One patient revealed intense accumulation of the radiotracer in a primary skin lesion of the thorax, whereas the other patient showed increased Tc-99m MIBI uptake in a lymph node metastasis of the neck. Tc-99m MIBI imaging could be helpful in the evaluation of patients with suspicious skin lesions and in patients with known cutaneous malignant melanoma, in the investigation of lymph nodal invasion, local recurrence, and metastatic spread.

Adult↗
PubMed1993

Tc-99m isonitrile uptake in a brain metastatic lesion. Comparison with Tc-99m DTPA using planar and SPECT imaging.

Tc-99m isonitrile uptake in a metastatic brain tumor is demonstrated using planar and SPECT imaging. Comparison with Tc-99m DTPA shows a different distribution pattern and uptake intensity, suggesting a different mechanism for both tracers. It is possible that Tc-99m CPI could reflect metabolic activity of the tumor cells and might be useful to evaluate the grade of malignancy as well as the recurrence of brain tumors.

Brain Neoplasms↗
PubMed1992

Human pharmacokinetics and radiopharmacological studies of the myocardial perfusion agent: technetium (2-carbomethoxy-2-isocyano-propane)6+.

The myocardial perfusion agent technetium (2-carbomethoxy-2-isocyano-propane)6+ (99mTc-CPI) is unique from other cationic technetium isonitrile complexes in that it exhibits moderate washout from the heart and rapid hepatobiliary clearance in animal models and human volunteers. Dynamic imaging and HPLC analysis were performed in humans and guinea pigs to outline the pharmacological basis of its pharmacokinetics. Enzymatic hydrolysis of the terminal ester groups in blood was found to occur at a moderate rate producing new species that have been shown not to accumulate in heart tissue. However, after extraction by the heart, liver or kidneys, the 99mTc-CPI complex undergoes metabolism at a much slower rate than observed in the blood. Differences in hydrolysis rate and products obtained indicate separate mechanisms of hydrolysis occurring in blood and other organs. It is proposed that the heart washout occurring after hydrolysis produces a neutral compound which is no longer retained by the negative cytosolic and mitochondrial membrane potentials in myocardial tissue.

Adult↗
PubMed1988

Optimum processing protocols for volume determination of the liver and spleen from SPECT imaging with technetium-99m sulfur colloid.

A study of the effects of processing parameters on the determination of liver and spleen volume from SPECT data was performed. A method for volume determination using a threshold algorithm was calibrated against phantoms and applied to 60 patient studies. Good reproducibility was found using different projections and computing the volume on separate days. Variations of the measured volumes with the threshold value, reconstruction filter cutoff frequency and attenuation correction were investigated. Reconstruction parameters producing best image quality were also determined. A threshold of 25% of the maximum value in the organ was determined from phantom studies. Changes of 1% around this value yielded changes of 2-3% in the computed volume. No significant change was noted as cutoff frequencies varied between 0.4 and 0.85 of Nyquist (0.031 to 0.066 cycles/cm) for a third order Butterworth filter. Attenuation correction produced a decrease of 9% and 6% in liver and spleen measured volume respectively. Best image quality was obtained with 0.4 Nyquist (0.031 cycles/cm) cutoff frequency for third order Butterworth filter and attenuation correction. It is concluded that optimal parameters must be determined for any processing protocol, and must then be adhered to in future applications to insure clinical accuracy, especially those parameters demonstrating the most quantitative and qualitative sensitivity.

Algorithms↗