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Biomedical subjects

A Ahonen

Publications and source records attributed to A Ahonen.

At least 37 records · Page 2Linked to original sources
PubMed1995

Detection of cervical metastases of thyroid medullary carcinoma by MoAb anti-CEA scintigraphy and immunohistochemistry.

Four patients with medullary thyroid carcinoma (MTC) were examined using anti-carcinoembryonic antigen (CEA) scintigraphy. Two patients had positive and two normal scintigraphic findings, although all the patients had elevated blood test markers (calcitonin or CEA). One patient with clinical suspicion of MTC metastases had only a faintly positive anti-CEA image, although single-photon emission tomographic scanning was used to increase the sensitivity and resolution of the method. Therefore, digital image processing of the planar images was performed to obtain more detailed information. The analysis revealed distinct accumulation of the activity at the right side of the neck at 20 h post administration. The specificity of the antibody binding in the malignant cells was confirmed after surgery by immunohistochemical staining of the tumour specimens for CEA. Both conventional and confocal laser scanning microscopy revealed distinct positive staining, indicating that the results obtained from the anti-CEA scanning showed specific binding of the labelled antibody in the neoplastic tissue.

Adult↗
PubMed1995

Comparison of iodine-123 labelled 2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane and 2 beta-carbomethoxy-3 beta-(4-iodophenyl)-N-(3-fluoropropyl)nortropane for imaging of the dopamine transporter in the living human brain.

Several cocaine congeners are of potential for imaging the dopamine transporter (DAT). Previous studies have shown that iodine-123 labelled 2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([123I] beta-CIT) is a promising radiotracer for imaging the serotonin (5-HT) and dopamine (DA) transporters in the living human brain with single-photon emission tomography (SPET). [123I] beta-CIT was found to be not very practical for 1-day DAT imaging protocols since peak DAT uptake occurs later than 8 h. Here we report a pilot comparison of [123I] beta-CIT and 2 beta-carbomethoxy-3 beta-(4-iodophenyl)-N-(3-fluoropropyl)nortropane ([123I] beta-CIT-FP), using SPET imaging in four healthy male subjects. Peak uptake of [123I] beta-CIT-FP into the basal ganglia occurred earlier (3-4 h after injection of tracer) than that of [123I] beta-CIT (> 8 h). However, the specific DAT binding of [123I] beta-CIT-FP in the basal ganglia was somewhat less (0.813 +/- 0.047) than that of [123I] beta-CIT (0.922 +/- 0.004). Imaging quality is excellent with both tracers and they are potentially of value for brain imaging in various neuropsychiatric disorders.

Brain↗
PubMed1995

Auditory evoked magnetic fields to tones and pseudowords in healthy children and adults.

Neuromagnetic responses to tones and pseudowords were measured with a 24-channel magnetometer in nine adults and in 23 children, the latter aged 0.3-15 years. Both stimulus types elicited substantially similar responses in all subjects. At 0.9-s interstimulus interval (ISI), the adult response was a stable P1m-N1m-P2m-N2m sequence peaking at 50, 100, 200, and 250 ms, respectively. A biphasic P1m-N1,2m response with peaks at 100 and 260 ms occurred in children up to 12 years of age. At longer ISIs (1.2-2.4 s), an adult-type N1m response appeared in most children. N1m amplitude suppression at short ISIs was stronger in children than in adults and may reflect a longer refractory period of the N1 generator neurons during early childhood than later in life. Peak latencies of P1m, N1m, and N2m decreased with age, most rapidly < 7 years of age. All deflections originated in nearby cortical areas within the posterior sylvian fissure, and may serve as functional landmarks for that anatomic area.

Adolescent↗
PubMed1994

The dosimetry of iodine-123 labelled 2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane.

This report documents the radiation dosimetry of iodine-123 labelled 2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane [123I]beta-CIT in humans. The mean absorbed doses for various organs and the effective dose equivalent were estimated from whole-body scans, blood samples and single-photon emission tomography scans acquired up to 22 h after the injection of a known amount of tracer. The basal ganglia, the liver and the lower large intestinal wall received the highest mean absorbed doses of 0.270 mGy/MBq, 0.038 mGy/MBq and 0.034 mGy/MBq, respectively. The effective dose equivalent for adults was estimated using 11 organs and the ICRP-87 radiation dose model and was 0.031 mSv/MBq. The radiation dose to the basal ganglia limits the maximum injected activity of [125I]beta-CIT to 185 MBq for a single study.

Adult↗
PubMed1994

Activation of the human posterior parietal cortex by median nerve stimulation.

We recorded somatosensory evoked magnetic fields from ten healthy, right-handed subjects with a 122-channel whole-scalp SQUID magnetometer. The stimuli, exceeding the motor threshold, were delivered alternately to the left and right median nerves at the wrists, with interstimulus intervals of 1, 3, and 5 s. The first responses, peaking around 20 and 35 ms, were explained by activation of the contralateral primary somatosensory cortex (SI) hand area. All subjects showed additional deflections which peaked after 85 ms; the source locations agreed with the sites of the secondary somatosensory cortices (SII) in both hemispheres. The SII responses were typically stronger in the left than the right hemisphere. All subjects had an additional source, not previously reported in human evoked response data, in the contralateral parietal cortex. This source was posterior and medial to the SI hand area, and evidently in the wall of the postcentral sulcus. It was most active at 70-110 ms.

Adult↗
PubMed1994

A Finnish multicentre quality assurance project in bone scintigraphy and brain SPET: a phantom study.

We examined all routinely used bone scintigraphy and brain single photon emission tomographic (SPET) systems in 19 laboratories in Finland. Physical performance of bone scintigraphy systems was measured with a 57Co flood source and with a NEMA resolution phantom. Total performance of the systems was evaluated with a transmission phantom simulating bone imaging of the thorax. It was acquired both with the protocol used in a given laboratory and with a fixed protocol. The participant laboratories were asked to report all accumulations on a diagrammatic thorax drawing. Tomographic uniformity, contrast and resolution (i.e. physical performance) of the SPET systems were evaluated with a special phantom. In addition, a Hoffman brain phantom was measured with routinely used acquiring and reconstruction protocols (total performance). All measurements were performed with the same test objects supervised by the same physicist. Manufacturer, age or the collimator of the camera did not correlate with the physical performance of the imaging systems (r < 0.65). This is probably due to lack of regular quality control of the gamma cameras in some laboratories. Comparison of the physical and the total performance shows that the detector itself is not necessarily responsible for inaccurate findings from the test object. Use of dual intensity and digital images in both scintigraphy could certainly increase the sensitivity of the findings: sensitivity of single intensity images was 65% (33-89%), dual 73% (28-100%), analog 65% (28-100%) and digital 74% (50-94%). Standardization of acquisition and reconstruction protocols will improve quality of brain SPET images and comparability between laboratories. This study showed the need for objective audit tests of bone scintigraphy and brain SPET systems in Finland.

Bone and Bones↗
PubMed1994

Samarium-153-EDTMP in bone metastases.

Thirty-five patients with painful bone metastases arising from a variety of tumor types underwent a clinical trial in which 153Sm-EDTMP was injected as a single intravenous dose. The injection ranged in amount from 330 MBq to 1110 MBq of 153Sm-EDTMP. Pain relief usually occurred within one week after administration. The duration of pain relief lasted from 2 to 17 weeks. A detectable degree of pain palliation was experienced by 80% of the treated patients; 54% reported substantial or complete pain relief. Due to the small number of patients, no clear-cut dose-related response was detectable. Moderate myelosuppression was observed in one patient (WHO grade III). The metastatic lesion-to-normal bone ratios remained constant (varying from 1.5 to 4.8) for at least 5 days post-injection. 153Sm cleared very rapidly from the blood. Less than 1% of the injected dose remained in circulation at 4 hours post-injection. No local accumulation of the tracer could be detected outside the skeleton. Urinary excretion was quite complete at 6 hours post-injection. The biodistributions of 153Sm-EDTMP and 99mTc-DPD are very similar in metastatic and normal bone; thus, bone scanning can be used for patient selection and followup. According to our results, it seems that higher doses of 153Sm-EDTMP can be given safely and without any irreversible myelosuppression.

Bone Neoplasms↗
PubMed1994

[123I] beta-CIT, a tracer for dopamine and serotonin re-uptake sites: preparation and preliminary SPECT studies in humans.

beta-CIT (2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane) is a new ligand that has a high affinity to dopamine and serotonin re-uptake sites. [123I] beta-CIT was prepared by reacting the corresponding trimethylstannyl precursor with no-carrier-added 123I. Iodogen was used as an oxidizing agent. The labeling mixture was purified by filtration through a mini-column. The purity of the product was confirmed by analytical HPLC. The total radiochemical yield was 67 +/- 5%. The radiochemical purity was > 95% and the specific activity was > 107 GBq/mol (> 2900 Ci/mmol). The final product was confirmed to be free of endotoxins before intravenous administration. Two healthy male volunteers were injected iv with 120-160 MBq of [123I] beta-CIT and scanned with a 3-head gamma-camera (Siemens MultiSPECT3). Dynamic SPECT scans were performed for up to 2 hours. There was a high accumulation of radioactivity in the striatum and in the thalamus, and some in the medial prefrontal area. Thus, we have developed an easy method to prepare [123I] beta-CIT with a high specific radioactivity and in a sufficient radiochemical yield. Specific [123I] beta-CIT binding in striatal and thalamic regions was demonstrated in humans. [123I] beta-CIT is a potential marker of the dopamine and serotonin transporters and can be used to study the pathophysiology of Parkinson's disease, as well as neuropsychiatric disorders.

Adult↗
PubMed1994

In vivo behavior of 111In-labeled monoclonal anti-prostatic acid phosphatase antibody after intraprostatic and intravenous injections.

The 111In-labeled monoclonal anti-prostatic acid phosphatase (PAP) monoclonal antibody F(ab')2 fragment was used for the radioimmunodetection of prostate cancer in two different patient groups: 15 patients with surgically verified T1-2 prostate cancer were imaged prior to staging lymphadenectomy and total prostatectomy using lymphatic administration (intraprostatic (ipr) injection), and 15 patients with verified metastatic prostatic cancer were imaged after intravenous (i.v.) injection. The patients were studied on several occasions (at 0-180 hours) after injecting a 1 mg MoAb fragment labeled with 75-150 MBq111In (DTPA-chelation). The extirpated tissues were counted for radioactivity, and studied immunohistochemically (IHC) and histologically. The anti-PAP MoAb was labeled with high efficiency (87-99%) and it demonstrated good immunoreactivity (90-95%) and a high affinity to the target antigen. In the excised prostates, cut into 12-18 smaller pieces, there was a clear correlation between the PAP content (as detected by IHC) and absolute radioactivity (% ID of 111In anti-PAP/g prostate). However, there was no correlation between radioactivity and the amount of cancer tissue (% of histological slices) inside the removed prostate tissue. In the pharmacokinetic studies, maximum activity in the serum was obtained within 3-5 hours after ipr injection; after that the kinetic behavior was similar to that after i.v. injection. After i.v. injection, two components could be distinguished the pharmacokinetic curves; the half-lives for mean distribution and elimination were 0.62 and 35.6 hours, respectively. The mean distribution half-life as well as the AUC from the pharmacokinetic curves correlated significantly with serum PAP (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1994

Incorporation and clinical results of large allografts of the extremities and pelvis.

The results of implantation of 37 large deep-frozen allografts with 29 osteoarticular grafts of the extremities and pelvis following the resection of malignant or aggressive benign bone tumors were evaluated at followup (mean, 6 years; range, 2.5-20 years). The patients had excellent or good results in 62% of all cases according to the Mankin-Waber functional rating score, and a corresponding rating of 81% in the Musculoskeletal Tumor Society Score. Benign versus malignant disease rated 83% and 76%, respectively, in the Musculoskeletal Tumor Society Score, and 67% and 46%, respectively, in the Mankin-Waber score. Radiological and nuclear medicine (single-photon emission computed tomography) studies and histological biopsies indicated that the incorporation, perfusion, and replacement with new bone was only partial and of a low degree. Late degenerative cartilage and sclerotic changes occurred in 20 of 29 cases with osteoarticular grafts. The best functional results were achieved with knee osteoarticular allografts (81%-88%) compared with modest results in the proximal humerus (69%) and hemipelvis (57%) according to the Musculoskeletal Tumor Society Score rating. Chemotherapy did not influence the union or infection rate of the allografts. In the 4 cases (11%) with infection, all grafts could be salvaged, but the functional results were only 63% in the Musculoskeletal Tumor Society Score. The overall complication rate was high (57%); graft-related complications occurred in 43%, including fatigue fractures in 27%. There were no cases of nonunion at the host graft junction. Clinical rejection did not occur. These clinical results may be improved in the future by new technology that uses bone substitutes, growth factors, and bone morphogenetic proteins.

Adult↗
PubMed1993

Parietal epileptic mirror focus detected with a whole-head neuromagnetometer.

Whole-head magnetoencephalographic recordings revealed two parietal epileptic foci in homotopic areas of the hemispheres. The discharges occurred 17-20 ms later on the left than on the right hemisphere, implying the existence of a left-sided mirror focus. The foci were about 1 cm posterior to the hand primary somatosensory area, identified by evoked response measurements, and thus suggested epileptic activity at the parietal association cortex, in agreement with the observed callosal conduction time.

Adolescent↗
PubMed1993

Cerebral trauma and alcohol abuse.

We report results of clinical examinations, computed tomography, quantitative electroencephalography (QEEG), and cerebral blood flow measurements performed on a series of 56 consecutive brain injury patients including 15 alcohol abusers and 41 non-alcoholic subjects. Greater volumes of intracranial haemorrhage were noted in the alcoholics for a similar severity of injury and local brain atrophy became more pronounced in them during a follow-up of 1 year. After this time, the third ventricle width, distance between frontal horns, the sum of lateral ventricle dimensions and cortical sulci were all markedly larger in the alcoholics. The QEEG results also indicated a weaker improvement in the alcoholics. The cerebral blood flow at the site of the injury was initially slow in the alcoholics when compared to the contralateral region of the other hemisphere, although these differences disappeared during the follow-up. Permanent occupational disability was also found to be associated with pretraumatic alcohol abuse. The findings indicate that ethanol abuse is not only commonly associated with cerebral trauma but is also a risk factor for a more severe brain damage following the injury.

Adult↗
PubMed1993

Radioimmunodetection of prostate cancer by 111In-labeled monoclonal antibody against prostatic acid phosphatase.

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragments were labeled with indium-111 chloride. This labeled antibody was tested in 15 prostate cancer patients who underwent staging pelvic lymphadenectomy; 9 of them received labeled antibody alone whereas 6 received simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blood measurements and imaging procedures indicated that simultaneous injection of unlabeled antibody reduced both the blood elimination rate and the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a couple of patients accumulation was noted also in normal lymph nodes. The method cannot in its present design replace staging pelvic lymphadenectomy and further studies are needed for elaboration of clinically useful radioimmunodetection methods.

Acid Phosphatase↗
PubMed1993

The value of quantitative analysis of glucose utilization in detection of myocardial viability by PET.

To study whether absolute quantitation of regional myocardial glucose utilization (rMGU) enhances detection of myocardial viability, 70 nondiabetic patients with prior myocardial infarction and angiographically confirmed coronary artery disease were studied with [18F]FDG PET after oral glucose loading. Forty-eight patients were also revascularized and underwent echocardiography after revascularization to detect wall motion recovery. The rMGU was calculated in eight myocardial segments in each patient and the results were compared to normalized (relative) [18F]FDG uptake values. In normal segments (n = 225), rMGU was 56 +/- 18 mumole/min/100 g (mean +/- s.d.) and relative [18F]FDG uptake 97% +/- 12%. The interindividual variation of rMGU in normal myocardium was greater than the intraindividual variation (s.d. 31% versus 11%). The respective values for relative [18F]FDG uptake were 9% and 10%. Both rMGU and [18F]FDG uptake were significantly reduced in segments with scarring observed visually during bypass surgery (29 +/- 19 mumole/min/100 g and 45% +/- 22%, n = 26). The rMGU and [18F]FDG uptake were higher in segments that recovered after revascularization (53 +/- 17 mumole/min/100/g and 110% +/- 21%, n = 27) than in those that did not (37 +/- 20 mumole/min/100 g and 65% +/- 24%, n = 63). However, due to larger variability of rMGU values, normalized [18F]FDG uptake was superior to rMGU in separating normal and scar segments as well as in predicting wall motion recovery. We conclude that rMGU variability is notable and is caused mainly by variations between patients. Interindividual variation is reduced by normalization, which results in more accurate assessment of myocardial viability. Thus, static imaging and semiquantitative analysis are sufficient for the clinical assessment of myocardial viability.

Coronary Angiography↗
PubMed1992

Euglycemic hyperinsulinemic clamp and oral glucose load in stimulating myocardial glucose utilization during positron emission tomography.

To enable assessment of myocardial viability, myocardial glucose utilization has commonly been stimulated by oral glucose loading. To compare the effects of glucose loading and insulin and glucose infusion (insulin clamp) on PET fluorodeoxyglucose ([18F]FDG) myocardial scan image quality and regional myocardial glucose utilization rate (rMGU), eight patients with angiographically documented coronary artery disease and previous myocardial Q-wave infarction were studied twice, once during insulin clamp and once 1 hr after oral glucose loading. The rMGU rates were derived by graphic Patlak analysis in 33 normal, 10 scar and 6 "hot spot" myocardial segments. Infusion of insulin and glucose gave stable plasma-glucose and serum-insulin levels during imaging. In contrast, glucose loading caused marked changes in plasma-glucose and insulin concentrations. The image quality was clearly superior and the fractional utilization rates of [18F]FDG were twice as high during insulin clamp than after glucose loading (p less than 0.0001). Due to the higher plasma-glucose levels after glucose loading, the calculated rMGU in normal, scar and hot spot myocardial segments was comparable between the two protocols. The insulin clamp technique makes it possible to adjust and maintain a metabolic steady state during the PET study. It does not alter [18F]FDG uptake patterns in different myocardial areas when compared to the standard glucose loading protocol, but this technique results in superior image quality and permits the use of smaller [18F] FDG patient doses.

Administration, Oral↗
PubMed1991

Auditory evoked magnetic fields after ischemic brain lesions.

Auditory evoked magnetic fields to noise/square-wave sequences, presented once every 2.2 seconds, were recorded in 8 patients who had ischemic lesions in the auditory cortex or in its vicinity. In 2 patients with large temporoparietal lesions, the magnetic 100-msec deflection (N100m) was absent over the damaged side. In 1 patient with a large but less deep frontotemporal lesion, a small N100m could be discerned on the defective side. Frontal lesions or small lesions in the vicinity of the supratemporal plane had no effect on N100m. Auditory evoked magnetic field recordings may be useful in clinical studies of auditory cortical functions.

Adolescent↗
PubMed1991

Radiation effects on uptake of 99Tcm-hexamethylpropylen amine oxime (HMPAO) in head and neck tumours.

Twenty patients with malignant head and neck tumours were imaged with 99Tcm-labelled hexamethylpropylene amine oxime (HMPAO), a radiopharmaceutical generally used for blood flow studies. Before radiotherapy (RT), 93% of the tumours could be detected with single photon emission computed tomography (SPECT) and 45% with planar imaging. Whole tumour-to-background 99TcmHMPAO uptake ratios ranged from 3.6 to 1.0 (mean 1.7 +/- 0.6) in untreated tumours. There was a good correlation between tumour volume and uptake (r = 0.69, P = 0.002). Sixteen patients were reimaged during or shortly after radical RT. 99TcmHMPAO uptake was significantly lower after treatment (mean uptake ratio 1.2 +/- 0.3, P less than 0.001). However, RT associated changes in 99TcmHMPAO uptake were in agreement with the clinical response in only 63% of the studies. This study indicates that 99TcmHMPAO SPECT imaging can be used for pretherapeutic localisation of head and neck tumours. Although most tumours show a decrease in uptake after irradiation the poor association with tumour regression does not allow for reliable assessment of treatment response.

Adult↗