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Biomedical subjects

W H Knapp

Publications and source records attributed to W H Knapp.

At least 55 records · Page 3Linked to original sources
PubMed2000

Plasma levels of cavernous and systemic norepinephrine and epinephrine in men during different phases of penile erection.

PURPOSE: Knowledge of the functional anatomy, hemodynamics, neurophysiology and pharmacology of penile erection has improved tremendously during the last 2 decades. However, only few in vivo studies on human peripheral neurotransmission have been carried out up until now. Therefore, we conducted a study to examine plasma levels of catecholamines norepinephrine (NE) and epinephrine (E) in the peripheral and cavernous blood of healthy men during penile flaccidity and in different phases of erection. MATERIALS AND METHODS: Blood samples were drawn simultaneously from the corpus cavernosum (CC) and the cubital vein (P) in 53 healthy volunteers with normal erectile function, in four different functional states of the cavernous erectile tissue (flaccidity = 1, tumescence = 2, rigidity = 3, detumescence = 4). Penile erections were induced by audiovisual and tactile stimulation and the plasma concentrations of NE and E were determined by means of a radioimmunoassay (RIA). RESULTS: A significant (p <0.001) reduction of NE in CC plasma was found from flaccidity (362 + or - 173 pg./ml.) to rigidity (248 + or - 122 pg./ml.), followed by an increase in the detumescence phase (336 + or - 199 pg./ml.), (p <0.001). In contrast, changes in NE levels in the peripheral plasma were less pronounced from 1P (202 + or - 102 pg./ml.) to 3P (229 + or - 118 pg./ml.), (p = 0.006) and from 3P to 4P (222 + or - 127 pg./ml.), respectively (p = 0.370). The most pronounced increase in cavernous E levels were observed from flaccidity (47 + or - 41 pg. /ml.) to tumescence (130 + or - 106 pg./ml.) (p <0.001). Cavernous E levels dropped significantly from 113 + or - 67 pg./ml. during rigidity to 76 + or - 57 pg./ml. + or - during detumescence (p <0.001). The course of peripheral plasma levels of E was similar to that in the cavernous blood. Mean peripheral E level was 69 + or - 55 pg./ml. in the state of penile flaccidity, reaching 98 + or - 78 pg./ml. in tumescence and 82 + or - 64 pg./ml. in rigidity (p <0.001), respectively, and finally decreasing to 62 + or - 46 pg./ml. in detumescence. CONCLUSION: Penile erection, based on the relaxation of cavernous and arterial smooth muscle, is accompanied by a significant reduction of NE in cavernous blood, while E levels rose in peripheral and cavernous blood during developing erection.

Adult↗
PubMed2000

Possible role of human growth hormone in penile erection.

PURPOSE: Treatment with recombinant human growth hormone in adult patients with growth hormone deficiency increases nitric oxide and cyclic guanosine monophosphate (cGMP). We examined the functional in vitro effects of recombinant human growth hormone on tissue tension and cyclic nucleotide levels of human corpus cavernosum and detected changes in growth hormone in the cavernous and peripheral blood during different phases of penile erection. MATERIALS AND METHODS: Relaxant responses of human corpus cavernosum were investigated using the organ bath technique. Tissue levels of cGMP were determined by a specific radioimmunoassay after dose dependent exposition of isolated human corpus cavernosum strips to recombinant human growth hormone. In 35 healthy potent volunteers blood samples were obtained simultaneously from the corpus cavernosum and cubital vein during different functional conditions of the penis, including flaccidity, tumescence, rigidity and detumescence. Penile erection was induced by audiovisual and tactile stimulation. Serum growth hormone was determined by an immunoradiometric assay. RESULTS: Recombinant human growth hormone elicited dose dependent relaxation of human corpus cavernosum strips in vitro. The relaxing potency of recombinant human growth hormone was paralleled by its ability to elevate intracellular levels of cGMP. In vivo the peripheral growth hormone serum profile of the respective penile conditions did not significantly differ from those of cavernous serum. The main increase in growth hormone to greater than 90% was determined during developing penile tumescence, followed by a transient decrease afterward. CONCLUSIONS: These results suggest that penile erection may probably be induced by growth hormone through its cGMP stimulating activity on human corpus cavernosum smooth muscle.

Adult↗
PubMed1999

Positive correlation between reduction of handwriting area and D2 dopamine receptor occupancy during treatment with neuroleptic drugs.

We investigated the relationship between fine extrapyramidal-motor symptoms (reduction of handwriting area) and D2 dopamine receptor occupancy under neuroleptic treatment. The handwriting of 18 schizophrenic patients before and during treatment with typical (haloperidol, haloperidol decanoate) and atypical (clozapine, risperidone) neuroleptic drugs was examined. Data analysis of the handwriting's examination was carried out with a planimetric computer programme. At the time of the second test of handwriting, D2 receptor occupancy was determined with single photon emission tomography (SPET) using [(123)I]iodobenzamide ((123)I-IBZM). In all patients, a reduction of handwriting area and a D2 receptor occupancy were found. The correlation between reduction of handwriting area and D2 receptor occupancy for typical and atypical neuroleptic drugs was linear and statistically significant (r=0.9; P > 0.001). Our findings point to the possibility that the reduction of handwriting area may be used as a clinical indicator of D2 receptor occupancy under treatment with neuroleptic drugs.

Adult↗
PubMed1999

Economic evaluation studies in nuclear medicine: the need for standardization.

The guidelines for publishing economic evaluations require a statement of the economic importance of the analysis and the viewpoint from which it has been carried out, as well as specification of at least two alternative programmes or interventions, the form of economic evaluation, the outcome measure, the method of costing, the time horizon and adjustment for timing of costs and benefits (e.g. by a discount factor), and the allowance for uncertainties (e.g. by implementation of a sensitivity analysis). The decision analysis can be based on clinical trial data, on retrospective or administrative databases, or on modelling. The choice of outcome measures is the key issue in an economic evaluation. In cost-effectiveness analysis, benefits are usually measured in natural units. This is the form of economic evaluation most frequently used in nuclear medicine. Endpoints of effectiveness applied in studies in this field have been procedures avoided, procedures initiated, cardiac events, survival probability, morbidity, quality of life and protracted or failed surgical procedures. In other instances, surrogate endpoints have been used such as metastases detected, staging, viability or tumour response. This, however, limits comparability of cost-effectiveness considerably, as proof of a change in the health outcome cannot be obtained. Measures of utility such as QALYs (quality-adjusted life years) have so far only been applied for decision tree analysis. Useful examples of economic evaluation studies in nuclear medicine are presented here for fluorodeoxyglucose positron emission tomography (FDG-PET) in the preoperative staging of non-small cell lung cancer, for FDG-PET in differentiating indeterminate solitary pulmonary nodules, for somatostatin receptor scintigraphy in detecting metastases of carcinoid tumours, for routine preoperative scintigraphy with sestamibi in patients with parathyroid adenoma, for periodic measurement of thyroid-stimulating hormone in detecting mild thyroid failure, for diagnostic algorithms including a lung scan in patients with suspected pulmonary embolism, for myocardial perfusion imaging as an incremental prognostic factor in patients with coronary artery disease, and for the use of radioiodine as first-line therapy of Graves' hyperthyroidism and of toxic nodular goitres. Further evaluations of effectiveness or utility should be carried out within a multidisciplinary framework to ensure that nuclear medical procedures are included in the general management guidelines.

Cost-Benefit Analysis↗
PubMed1999

Iodo-QNB cortical binding and brain perfusion: effects of a cholinergic basal forebrain lesion in the rat.

This study deals with the question of whether in vivo application of [125I]iodo-quinuclidinyl-benzilate (QNB) is able to demonstrate changes in cortical muscarinic receptor density induced by a cholinergic immunolesion of the rat basal forebrain cholinergic system, and whether the potential effects on IQNB distribution in vivo are also associated with effects on regional cerebral perfusion. Immunolesioned and control animals were injected with (R,S) [125]iodo-QNB and with [99mTc]-d,l-hexamethylpropyleneamine oxime (HMPAO). The cerebral distribution of both tracers was imaged using double tracer autoradiography. Impaired cholinergic transmission was paralleled by a 10-15% increase of [125I]iodo-QNB binding in the regions of cortex and hippocampus. The local cerebral blood flow remained unchanged after cholinergic lesion.

Acetylcholine↗
PubMed1999

Extracorporeal rheopheresis in the treatment of acute ischemic stroke: A randomized pilot study.

BACKGROUND AND PURPOSE: Extracorporeal rheopheresis is a safe method to optimize hemorheology. Our aim was to determine whether treatment with extracorporeal rheopheresis in patients with acute ischemic hemispheric stroke improves cerebral perfusion as assessed with serial 99mTc-ethyl-cysteinate-dimer single-photon emission CT (99mTc-ECD SPECT). We also investigated how clinical outcome is associated with treatment and imaging results. METHODS: Thirty-three patients (mean age, 64+/-10 years) with acute ischemic hemispheric stroke were included in a prospective, randomized, parallel group pilot study. First treatment with or without extracorporeal rheopheresis took place within 12 hours after the onset of symptoms and was repeated 3 times at intervals of 24 hours. Hemorheological parameters were measured before and after each session. Each patient underwent 99mTc-ECD SPECT immediately before treatment, 6 to 8 hours after treatment, and after 5 days. A semiquantitative SPECT graded scale was used to measure depth and extent of activity deficits and thus to quantify the perfusion deficit. RESULTS: Seventeen patients were actively treated with extracorporeal rheopheresis, and 16 patients did not receive extracorporeal rheopheresis. After 3 months, no differences were found in the functional or neurological outcome. Despite a rapid, sustained decrease of plasma viscosity and erythrocyte aggregation in the rheopheresis group, there was no significant difference in the SPECT graded scale after therapy between the 2 groups. Patients with early reperfusion (decrease in the SPECT graded scale >25% 6 to 8 hours after therapy compared with the baseline examination) experienced a better functional outcome (Modified Rankin Scale) after 3 months compared with patients without reperfusion (P=0.04). CONCLUSIONS: Since quantitative flow mapping and clinical follow-up did not reveal any differences between patients who were treated with extracorporeal rheopheresis and controls, it appears very unlikely that extracorporeal rheopheresis enhances reperfusion after acute cerebral ischemia.

Acute Disease↗
PubMed1999

A positron emission tomography study of cerebrovascular reserve before and after shunt surgery in patients with idiopathic chronic hydrocephalus.

OBJECT: In this study the authors use positron emission tomography (PET) to investigate cerebral blood flow (CBF) and cerebrovascular reserve (CVR) in chronic hydrocephalus. METHODS: Ten patients whose mean age was 67 +/- 10 years (mean +/- standard deviation [SD]) were compared with 10 healthy volunteers who were 25 +/- 3 years of age. Global CBF and CVR were determined using (15)O-H2O and PET prior to shunt placement and 7 days and 7 months thereafter. The CVR was measured using 1 g acetazolamide. Neurological status was assessed based on a score assigned according to the methods of Stein and Langfitt. Seven months after shunt placement, five patients showed clinical improvement (Group A) and five did not (Group B). The average global CBF before shunt deployment was significantly reduced in comparison with the control group (40 +/- 8 compared with 61 +/- 7 ml/100 ml/minute; mean +/- SD, p < 0.01). In Group A the CBF values were significantly lower than in Group B (36 +/- 7 compared with 44 +/- 8 ml/100 ml/minute; p < 0.05). The CVR before surgery, however, was not significantly different between groups (Group A = 43 +/- 21%, Group B = 37 +/- 29%). After shunt placement, there was an increase in the CVR in Group A to 52 +/- 37% after 7 days and to 68 +/- 47% after 7 months (p < 0.05), whereas in Group B the CVR decreased to 14 +/- 18% (p < 0.05) after 7 days and returned to the preoperative level (39 +/- 6%) 7 months after shunt placement. CONCLUSIONS: The preliminary results indicate that a reduced baseline CBF before surgery does not indicate a poor prognosis. Baseline CBF before shunt placement and preoperative CVR are not predictive of clinical outcome. A decrease in the CVR early after shunt placement, however, is related to poor late clinical outcome, whereas early improvement in the CVR after shunt placement indicates a good prognosis.

Aged↗
PubMed1999

Improvement of brain SPECT by stabilization of Tc-99m-HMPAO with methylene blue or cobalt chloride. Comparison with Tc-99m-ECD.

AIM: This present study was carried out to investigate whether stabilization of Tc-99m-HMPAO with methylene blue (MB) or cobalt chloride (CC) causes a sensible improvement in image quality and how cerebral to noncerebral activity ratios compare with those of Tc-99m-ECD. METHODS: 30 minutes after preparation 400-600 MBq unstabilized Tc-99m-HMPAO (N = 35 patients), Tc-99m-HMPAO added with MB (N = 24 patients), added with CC (N = 30 patients) or Tc-99m-ECD (N = 28 patients) were injected. Radiochemical stability was measured in vitro with three chromatographical methods. Image quality was assessed quantitatively using two ratios, one of them determined by count densities of brain/scalp (Os), the other one by count densities of brain/nose (QN). In addition, image quality (0 = bad, 3 = excellent) and background activity (0 = high, 3 = no) were visually assessed by three independent observers. RESULTS: In contrast to unstabilized Tc-99m-HMPAO the integrity of the complexes of MB-Tc-99m-HMPAO, CC-Tc-99m-HMPAO and Tc-99m-ECD decreased only by a few percent during a period of 2 hours after reconstitution (66.8 +/- 9.9 vs. 93.0 +/- 2.5, 91.8 +/- 1.9 and 96.9 +/- 1.4%, p < 0.001). Qs and Qn (m.v. +/- SD) differed significantly between studies using unstabilized Tc-99m-HMPAO (3.0 +/- 0.4 and 2.1 +/- 0.3), MB-Tc-99m-HMPAO (3.4 +/- 0.4 and 2.3 +/- 0.3), CC-Tc-99m-HMPAO (3.6 +/- 0.6 and 2.6 +/- 0.4) and those using Tc-99m-ECD (4.3 +/- 0.7 and 4.8 +/- 1.4, p < 0.05 and < 0.001). Stabilization with CC or MB resulted in significant higher scoring of image quality and lower scoring of background activity in comparison to that of unstabilized Tc-99m-HMPAO, without reaching the scores obtained with Tc-99m-ECD. CONCLUSIONS: It is concluded that stabilization of Tc-99m-HMPAO with MB or CC definitely improves image quality in rCBF-SPECT, without reaching that of Tc-99m-ECD. Improvement of image quality results from the reduction of the amount of decomposition products that contribute to considerable extracerebral activity.

Adult↗
PubMed1999

Monitoring of graft perfusion and osteoblast activity in revascularised fibula segments using [18F]-positron emission tomography.

The aim of the present study was to evaluate healing of revascularised fibula grafts used for mandibular reconstruction using [18F]fluoride ion and positron emission tomography (PET). Sixteen PET studies in 11 fibula grafts were analysed to determine both blood flow and fluoride influx as a measure of vascularisation and osteogenic activity. Two graft failures and three non-unions were encountered and were compared to the successfully healed grafts. In uneventful graft healing, early PET studies (on average 19 days after grafting) showed a significantly increased blood flow to the grafted bone and to the union between the grafts and the mandibles when compared to the reference region of the cervical spine. In contrast, fluoride influx was significantly lower in the grafts when compared to the plating area and the cervical spine. Six months after grafting, blood flow to the grafted bone and the mandibular bone had returned to a level comparable with the reference region. Fluoride influx remained significantly lower in the grafts than in the plating areas or cervical spines. Graft failures were associated with negligible fluoride influx near zero in early PET studies. These results suggest that revascularised fibula grafts provide a low osteogenic potential, presumably due to the pre-existing lack of cancellous bone. The relatively high frequency of non-unions makes meticulous adaptation of the graft and the mandible mandatory, particularly in patients with compromised viability of the recipient bone.

Bone Plates↗
PubMed1998

Differentiation between transient ischemic attack and ischemic stroke within the first six hours after onset of symptoms by using 99mTc-ECD-SPECT.

The aim of this study was to define the accuracy of 99mTc-ethyl cysteinate dimer-single photon emission computed tomography (99mTc-ECD-SPECT) in distinguishing transient ischemic attack from completed ischemic stroke at early stages after the onset of symptoms. In a prospective study we examined 82 patients within 6 hours after the onset of symptoms (neurologic deficit caused by middle cerebral artery ischemia) using both 99mTc-ECD-SPECT and computed tomography (CT). The follow-up was based on Scandinavian Stroke Scale (SSS) 24 hours and 5-7 days, as well as on CT 7 days, after the event. SPECT evaluation was performed both visually and using semiquantitative region-of-interest (ROI) analysis. According to visual SPECT analysis, on admission 59 of 82 patients had activity deficits in the symptomatic hemisphere. After 7 days, all these patients had neurologic symptoms (SSS 28 +/- 12 points), caused by a cerebral infarction as evidenced with CT. Twenty-three of 82 patients displayed no early activity deficit despite clinical symptoms. None of these patients had neurologic symptoms after 7 days (indicating transient ischemic attack or prolonged reversible ischemic neurologic deficit). In the semiquantitative SPECT analysis, all patients had abnormal count densities in the respective ROI (activity < 90% compared with the contralateral side). All patients with transient ischemia (n = 23) had count rate densities more than 70% of the respective contralateral ROI, whereas all patients with subsequent infarction (n = 59) had values < 70%. Use of 99mTc-ECD-SPECT allows transient ischemia to be distinguished from ischemic infarction using relative regional activity thresholds within the first 6 hours after onset of symptoms.

Adult↗
PubMed1998

PET and CBF studies of chronic hydrocephalus: a contribution to surgical indication and prognosis.

The authors investigate whether measurement of cerebral blood flow (CBF) in chronic hydrocephalus is a reliable indicator in selecting patients to undergo ventriculoperitoneal shunting. Global and regional CBF is quantified (Kety-Schmidt one-compartment model) by positron emission tomography in 21 patients. CBF is determined following injection of 15O-H2O at three time points: 1 week before, 7 days after, and 7 months after shunting. The neurological status of these patients is classified, and cerebrospinal fluid (CSF) dynamics continuous intracranial pressure [ICP] monitoring and CSF infusion tests) were assessed prior to surgery. Preoperative global CBF values correlate well with clinical outcome. Patients with a significantly lower global CBF value show clinical improvement after 7 months, whereas patients with higher CBF values do not (mean, 33 vs. 45 ml/100 ml per minute; p < 0.05). In contrast to conventional methods, including long-term ICP measurement and CSF infusion tests, preoperative global CBF values are discriminating in terms of clinical outcome. Thus, measurement of CBF may be helpful in evaluating the ultimate utility of shunt therapy in chronic hydrocephalus.

Aged↗
PubMed1998

99m technetium-ethyl-cysteinate-dimer single-photon emission CT can predict fatal ischemic brain edema.

BACKGROUND AND PURPOSE: We sought to study the prognostic value of early 99mtechnetium-ethyl-cysteinate-dimer single-photon emission CT (99mTc-ECD SPECT) for fatal ischemic brain edema in patients with middle cerebral artery (MCA) stroke compared with the prognostic value of CT and of clinical findings. METHODS: We prospectively studied 108 patients clinically, with 99mTc-ECD SPECT, and with CT within 6 hours of symptom onset (Scandinavian Stroke Scale <40 points) appropriate to MCA ischemia. The follow-up consisted of Scandinavian Stroke Scale and CT on days 1 and 7, Barthel Index, and Modified Rankin Scale after 3 months. An activity deficit of the complete MCA territory on the SPECT scans and a parenchymal hypoattenuation of the complete MCA territory on CT scans were considered as predictors for a fatal MCA infarction due to mass effect and midbrain herniation. RESULTS: In 11 of 108 patients (10%), the MCA infarction was the cause of death. The sensitivity of SPECT for fatal outcome was 82% in both visual and semiquantitative analyses, while specificity was 98% and 99%, respectively. The sensitivity and specificity of baseline CT were 36% and 100%, respectively; the sensitivity and specificity of clinical findings (Scandinavian Stroke Scale, depressed level of consciousness, gaze deviation) varied from 36% to 73% and from 45% to 88%, respectively. In a multivariate logistic regression model, only SPECT findings were found to be independent predictors of malignant MCA infarction/death. CONCLUSIONS: We were able to identify patients with fatal MCA infarction with high accuracy by using 99mTc-ECD SPECT within 6 hours of stroke onset. This technique offers great potential to select stroke patients for specific therapies, eg, decompressive hemicraniectomy, soon after onset of symptoms.

Adolescent↗
PubMed1998

[18F]fluoride PET indicates reduced bone formation in severe glucocorticoid-induced osteoporosis.

A 61-year-old female patient presenting with mixed connective tissue disease (Sharp syndrome), underwent a long-term high dose glucocorticoid treatment because of multiple organ manifestations. Under steroid therapy she developed severe osteoporosis resulting in multiple fractures. A dynamic [18F]fluoride PET study in this patient revealed reduced fluoride influx in non-fractured vertebrae. This finding corresponds to pathogenetic concepts which propose an inhibition of bone formation as major cause of glucocorticoid-induced osteoporosis. In the light of the presented case it seems to be promising to evaluate the diagnostic benefit of [18F]fluoride PET in osteoporosis.

Esophagus↗
PubMed1997

Attenuation correction by simultaneous emission-transmission myocardial single-photon emission tomography using a technetium-99m-labelled radiotracer: impact on diagnostic accuracy.

Irregular photon attenuation may limit the diagnostic accuracy of myocardial single-photon emission tomography (SPET). The aim of this study was to quantify the potential benefit of attenuation correction by simultaneous emission and transmission imaging for the detection of coronary artery disease (CAD) of vessels supplying the inferoposterior wall segments. In 25 male patients with >/=50% stenoses of the right coronary artery and/or circumflex artery but without significant narrowing of the left anterior descending artery, stress studies using technetium-99m tetrofosmin (400 MBq) were carried out with and without attenuation correction. A dual-head camera with L-shaped detector positioning was equipped with two scanning gadolinium-153 line sources. Tomograms were reconstructed and quantified using circumferential count rate profiles of myocardial activity (two in each patient). The profiles were compared with the respective normal ranges obtained from a database of 25 male patients with a <10% likelihood of CAD. In patients without CAD, the maximal differences in count density of different wall segments were reduced from 29.0% in non-corrected (NC) studies to 9.5% in attenuation-corrected (AC) studies. In particular, the inferoposterior and septal wall segments were represented by significantly increased relative count densities after attenuation correction. The effects of attenuation correction proved independent of body mass. In patients with CAD, segmental count densities were abnormal in 84% of the NC studies and 100% of the AC studies. In single-vessel disease the stenotic vessel was identified in 66% of cases by NC studies and in 100% by AC studies. In AC studies, the extent and depth of defects exceeded those in NC studies. For the detection of CAD of the right coronary artery, the receiver operating characteristic (ROC) curves relating to the AC studies demonstrated improved discrimination capacity (P<0.05). ROC analysis of CAD detection yielded normalcy rates of 82% (NC) and 94% (AC) for the circumflex artery and 65% (NC) and 97% (AC) for the right coronary artery area at a sensitivity level of 95%. It is concluded that attenuation correction using the above system may enhance the diagnostic accuracy of myocardial SPET when inferoposterior wall segments are to be evaluated.

Algorithms↗
PubMed1997

Age-specific cerebral perfusion in 4- to 15-year-old children: a high-resolution brain SPET study using 99mTc-ECD.

This study addresses the question of whether the normal range for distribution of local cerebral blood flow (lCBF) in adults can be transferred to the 4- to 15-year-old age group. Twenty-three children (age: 4-15 years; mean 11+/-3 years, group I) and 10 adults (age: 27-56 years; mean 45+/-10 years, group II) without evidence of cerebrovascular disease or other brain diseases underwent technetium-99m ethyl cysteinate dimer single-photon emission tomography. Counts in cortical and subcortical regions of interest (ROIs) were related to those in cerebellar ROIs (= 100%). Relative cortical activity in group I exceeded that in group II, particularly in left parietal (107.6%+/-9.8% vs 84.1%+/-12.4%), left frontal (97. 7%+/-6.7% vs 79.4%+/-8.9%) and left temporal areas (99.7%+/-7.4% vs 84.9%+/-10.1%) and in the cingulate cortex (112.1%+/-9.1% vs 95. 9%+/-10.1%, P<0.05). Cerebral activity uptake per injected dose was inversely correlated with age in 19 children of group I (r = -0.77, P<0.001). In group I, there was also an inverse correlation between age and the relative local count density in the parietal (r = -0.42 to -0.57), frontal (r = -0.48), temporal (r = -0.42 to -0.58) and occipital cortex (r = -0.44). In these cortical regions relative counts differed when subgroups of children aged 4-10 and 11-15 years were analysed. It is concluded that there are systematic differences between 4- to 15-year-old children and adults with regard to normal lCBF. Diagnostic use of perfusion agents has to consider age-adjusted normal flow maps; normal ranges should be determined separately for the age groups 4-10 and 11-15 years.

Adolescent↗
PubMed1997

[Age dependence of cerebral Tc-99m-ECD distribution between preschool and school-age children and adults].

AIM: This present study deals with the question whether normal distribution of local cerebral blood flow (ICBF) agents in adults can be transferred to the age group of 4 to 15 years old children. METHODS: 23 children (age: 4-15 years, mean 11 +/- 3 y) (group I) and 10 adults (age: 27-56 years, mean 45 +/- 10 y) (group II) without evidence of cerebrovascular disease or other brain diseases underwent Tc-99m-ECD-SPECT imaging. Counts in the cortical ROIs were related to those of cerebellar ROIs (= 100%). RESULTS: In group I, relative cortical activity exceeded that of group II, particularly in parietal (107.6 +/- 9.8 vs. 84.1 +/- 12.4%), frontal (97.7 +/- 6.7 vs. 79.4 +/- 8.9%), left temporal areas (99.7 +/- 7.4 vs. 84.9 +/- 10.1%) and in the singular cortex (112.1 +/- 9.1 vs. 95.9 +/- 10.1%, p < 0.05). Cerebral activity uptake/injected dose/acquisition period was linearly correlated with age in group I (r = -0.78, p < 0.001). There was also a correlation of the relative local count density with age in 5 parietal ROIs (r = -0.42 to -0.57), in 2 frontal ROIs (r = -0.48), in 7 temporal ROIs (r = -0.42 to -0.58) and in 2 occipital ROIs (r = -0.44). In 14 cortical regions relative counts differed when subgroups of children aged 4-10 and 11-15 years were analysed. CONCLUSION: There are systematic differences between 4 to 15 years old children and adults regarding the normal distribution of ICBF. Diagnostic use of perfusion agents has to consider the respective age-adjusted normal flow maps; respective normal ranges should be determined for age groups of 4-10 and of 11-15 years separately.

Adolescent↗