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M Clausen

Publications and source records attributed to M Clausen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Effect of attenuation correction on lesion detectability in FDG PET of breast cancer.

UNLABELLED: The aim of this study was to compare the visual analysis of attenuation-corrected and noncorrected 18F-fluoro-2-deoxy-D-glucose (FDG) PET images in patients with primary or metastatic breast cancer using standardized film documentation and to evaluate the influence of attenuation correction on lesion detectability. METHODS: Standard FDG PET of the breasts and of the axillary regions was performed on 28 women with breast cancer. Transmission scans were acquired for attenuation correction after administration of FDG. Transverse and coronal slices and maximum intensity projections both with and without attenuation correction were documented in a standardized manner on film. Noncorrected images were displayed with an upper threshold of five times the mean activity in normal lung tissue. Attenuation-corrected images were documented with an upper threshold of a standardized uptake value of five. Two independent nuclear medicine physicians, who were unaware of the results of clinical investigation, other imaging modalities and histopathologic findings, interpreted the images visually, noncorrected images first. RESULTS: One hundred eighty-four of 189 lesions in 28 of 28 patients were found on attenuation-corrected and noncorrected images. Seventeen lesions were found in the breasts of 12 patients. In 18 patients, 31 axillary lesions were found. Moreover, 141 lesions representing distant metastases were detected in 18 patients. Attenuation-corrected images showed the same lesions in all patients but 2, in whom 5 of 189 small pulmonary lesions (2.6%) were not detected. Iterative reconstruction did not improve detectability of these lesions on attenuation-corrected images. These lesions were confirmed by CT, which revealed diameters of <1 cm. CONCLUSION: Attenuation correction by transmission measurement after injection may impair lesion detectability in PET for staging of breast cancer patients. When using the image modalities described, noncorrected PET images should be considered in image analysis.

Axilla↗
PubMed1998

Histological verification of positive fluorine-18 fluorodeoxyglucose findings in patients with differentiated thyroid cancer.

Fluorine-18 fluorodeoxyglucose and positron emission tomography (FDG-PET) is a new imaging modality used in the follow-up of patients with differentiated thyroid cancer if the results of (131)I scintigraphy are negative in spite of an elevated thyroglobulin level. The aim of this retrospective analysis was to estimate the value of FDG-PET regarding the operability of patients with positive findings. From January 1994 to October 1997, we investigated 60 patients with differentiated thyroid carcinoma by FDG-PET. Thirteen patients were operated on after positive findings. Most of these lesions were suspected of having lymph-node involvement or local recurrences in the thyroid bed. One patient showed a solitary distant metastasis in the scapula. Thirteen of 16 operations in these 13 patients confirmed the suspected involvement of thyroid cancer. The false-positive findings were caused by inflamed lymph nodes in two cases and benign thymus tissue in one case. We conclude that PET is a useful diagnostic tool to guide early surgical therapy in patients with (131)I negative differentiated thyroid carcinoma.

Adenocarcinoma, Follicular↗
PubMed1998

[Computerized tomography and F-18-FDG positron emission tomography in staging of malignant lymphomas: a comparison].

PURPOSE: To determine the value of F-18-FDG-positron emission tomography (FDG-PET) compared with computed tomography (CT) in the staging of malignant lymphomas. MATERIAL AND METHOD: 50 patients with biopsy-proven lymphoma were studied with FDG-PET and CT. The results in initial, posttherapeutic and staging of recurrence were compared. RESULTS: 37 of 65 FDG-PET were identical with CT. 28 studies showed differences. 14 post-therapeutically and one of the initial studies led to downstaging by FDG-PET were as upstaging resulted in one case of initial staging. In two cases false positive pulmonary FDG accumulations caused an upstaging. CONCLUSION: FDG-PET was at least comparable to CT in recording the extension of a newly diagnosed lymphoma, or its recurrence. Upstaging according to FDG-PET occurred only once in initial staging. FDG-PET plays its most important role in the evaluation of residual mass in CT after therapy by accumulating FDG in viable tumour rather than in fibrotic tissue. 14 cases of downstaging according to FDG-PET resulted.

Adolescent↗
PubMed1998

Salivary gland protection by amifostine in high-dose radioiodine treatment: results of a double-blind placebo-controlled study.

PURPOSE: Salivary gland impairment is a well-recognized side effect following high-dose radioiodine treatment (HD-RIT). Since differentiated thyroid cancer has a good prognosis, reduction of long-term side effects is important. Therefore, the effect of amifostine was studied in HD-RIT. PATIENTS AND METHODS: Parenchymal function was assessed by quantitative salivary gland scintigraphy performed prospectively in 50 patients with differentiated thyroid cancer before and 3 months after HD-RIT with either 3 GBq iodine ((131)I) (n=21) or 6 GBq (131)I (n=29) in a double-blind, placebo-controlled study. Twenty-five patients were treated with 500 mg/m2 amifostine intravenously before HD-RIT and 25 patients served as controls, who received physiologic saline solution. Xerostomia was graded according to World Health Organization (WHO) criteria. RESULTS: Before HD-RIT in 25 control patients, uptake of technetium-99m (99mTc)-pertechnetate was 0.45%+/-0.16% and 0.42%+/-0.16% in parotid and submandibular glands, respectively. Three months after HD-RIT, parenchymal function was significantly (P < .001) reduced by 40.2%+/-14.1% and 39.9%+/-15.3% in parotid and submandibular glands, respectively. Nine control patients developed grade I and two grade II xerostomia. In 25 amifostine-treated patients, uptake of 99mTc-pertechnetate was 0.46%+/-0.16% and 0.43%+/-0.17% in parotid and submandibular glands, respectively. Three months after HD-RIT, parenchymal function of salivary glands was not significantly altered (P=.691) and xerostomia did not occur in any of these patients. CONCLUSION: Parenchymal damage in salivary glands caused by HD-RIT can significantly be reduced by amifostine, which may improve the quality of life of patients with differentiated thyroid cancer.

Adenocarcinoma, Follicular↗
PubMed1998

Radioprotection of salivary glands by amifostine in high-dose radioiodine therapy.

UNLABELLED: Salivary gland impairment after high-dose radioiodine treatment is well recognized. Because differentiated thyroid cancer has a good prognosis, reduction of long-term side effects is important. This study investigated the radioprotective effects of amifostine in animals and humans receiving high-dose radioiodine therapy. METHODS: Quantitative salivary gland scintigraphy was performed in five rabbits before and up to 3 mo after high-dose radioiodine therapy applying 1 GBq 131I. Three animals received 200 mg/kg amifostine before high-dose radioiodine therapy, and two served as controls. All animals were examined histopathologically. Quantitative salivary gland scintigraphy also was performed in 17 patients with differentiated thyroid cancer before and 3 mo after high-dose radioiodine therapy with 6 GBq 131I. Eight patients were treated with 500 mg/m2 amifostine before high-dose radioiodine therapy, and nine served as controls. RESULTS: In two control rabbits, high-dose radioiodine therapy significantly reduced parenchymal function by 63% and 46% in parotid and submandibular glands, respectively. In contrast, there was no significant decrease in parenchymal function in amifostine-treated animals. Histopathologically, lipomatosis was observed in control animals but was negligible in amifostine-treated animals. Similar findings were observed in differentiated thyroid cancer patients. In nine control patients, high-dose radioiodine therapy significantly (p < 0.01) reduced parenchymal function by 37% and 31% in parotid and submandibular glands, respectively. Three patients exhibited Grade I (World Health Organization) xerostomia. In contrast, there was no significant decrease in parenchymal function in amifostine-treated patients and no incidence of xerostomia. CONCLUSION: Parenchymal damage in salivary glands induced by high-dose radioiodine therapy can be reduced significantly by amifostine. This may increase the quality of life of patients with differentiated thyroid cancer.

Adenocarcinoma, Follicular↗
PubMed1998

[Chest X ray: routine indication in the follow-up of differentiated thyroid cancer?].

AIM: This retrospective study sought to elucidate whether routine chest x-ray is still useful for detection of pulmonary metastases in low risk patients despite the high sensitivity of the tumor marker thyroglobulin. METHOD: The hospital files of 609 patients with well-differentiated thyroid cancer were analysed. Pulmonary formation of metastases was diagnosed in 50 patients. The thyroglobulin value at the time of diagnosis was compared with the chest x-ray findings and, if present, additional diagnostic information such as Iodine-131 whole body scintigraphy (WBS) and thorax CT. RESULTS: The sensitivity of the chest x-ray to detect pulmonary metastases was at 52% lower than that of WBS (64%), thorax CT (82%) and thyroglobulin during suppression therapy (86%). Among the patients with papillary carcinoma stage I and II (UICC 1987), only 1 patient developed pulmonary metastases during follow up. In this low risk group of patients, detection of lung metastases exclusively by chest x-ray, without elevation of thyroglobulin level is extremely rare (calculated probability 1/4000) and associated with considerable costs. CONCLUSION: Routine, life long chest x-ray in low risk patients without a suspected recurrence (e.g. positive thyroglobulin) needs to be reconsidered.

Carcinoma, Papillary↗
PubMed1998

Somatostatin receptor scintigraphy in postsurgical follow-up examinations of meningioma.

UNLABELLED: Surgery is the treatment of choice in patients with meningioma. However, the risk of postoperative, local recurrence is well-known since total resection is not always feasible. Moreover, in these patients MRI may fail to differentiate between tumor remnants, recurrent meningioma or nonspecific hyperperfusion. In this study, the value of functional imaging using somatostatin receptor scintigraphy (SRS) was evaluated in postsurgical follow-up. METHODS: Before and 2-3 mo after surgery, 27 patients with meningioma received MRI as well as SRS after intravenous injection of 200 MBq 111In-octreotide. Planar whole-body images were obtained at 10 min, 1, 4 and 24 hr postinjection, and SPECT was performed at 4 and 24 hr postinjection. The final diagnosis was proven histologically in all patients. RESULTS: Before surgery, MRI showed focal contrast enhancement in all patients, and SRS revealed focal accumulation of 111In-octreotide. Thus, MRI and SRS yielded comparable results in all 27 patients. After surgery, MRI showed diffuse contrast enhancement in the area of the primary tumor site in all patients. Thus, MRI did not allow a differentiation between tumor and nonspecific hyperperfusion. In contrast, SRS revealed focal accumulation of 111In-octreotide in 16 of 27 patients indicating remaining tumor tissue or relapse of meningioma. This resulted either in an operative revision or in more frequent postsurgical follow-up examinations. In 11 of 27 patients, SRS was negative. Thus, total resection of meningioma was assumed, and no further interventions were performed. CONCLUSION: Functional imaging using SRS is a highly specific imaging modality and has a significant impact in postsurgical follow-up in patients with meningioma.

Female↗
PubMed1997

Quantification of diphosphonate uptake based on conventional bone scanning.

Up to now there has been no routinely used and easy-to-perform method for the quantification of bone uptake. Therefore, we have evaluated the clinical practicability of a new and simple method for the measurement of bone uptake based upon conventional three-phase bone scanning. In 13 patients with normal bone scans, whole-body scintigrams were obtained at 3 min and 1, 2, 3, 4, 5, 6 and 24 h after injection of 600 MBq technetium-99m hydroxymethylene diphosphonate (HMDP). Using a conventional region of interest technique, fitted time-activity curves of soft tissue and urinary excretion were established, and bone uptake was calculated from these data as the total whole-body activity minus both soft tissue activity and urinary excretion. Subsequently, the new method was tested in routine patient management: 32 healthy patients and five patients with different types of metabolic bone disease were investigated, measurements being performed only at 3 min and 3-4 h p. i. during conventional three-phase bone scanning. In the multi-imaged patient subset, soft tissue activity decreased exponentially, reaching a plateau after 6 h with a residual activity of about 14% of initial total whole-body activity. Bone uptake reached quite a stable plateau of about 27% as early as 3 h p.i., with no significant changes up to 24 h. Healthy patients of the two-scan group showed no differences in bone uptake (mean uptake values were 24.1% in women and 26.9% in men), whereas in patients with metabolic bone disease bone uptake was significantly higher, with a mean of 48% (P <0.05). Thus, the results of this method are in good agreement with the findings of standard 24-h whole-body retention measurements. The new method, however, is easy to perform, allows assessment of pure bone uptake instead of whole-body retention, and permits calculation of bone uptake by only two measurements during routine three-phase bone scanning.

Adult↗
PubMed1997

[Implementation and indications for quantitative sialoscintigraphy].

BACKGROUND: Since its introduction in 1965 salivary gland scintigraphy has been an established method to simultaneously investigate excretion function in major salivary glands. In order to elucidate parenchymal function of salivary glands, several authors described various quantitative and semiquantitative methods. However, no standardized protocol for quantitative salivary gland scintigraphy has been established so far. METHODS: Therefore, in this paper we report on a standardized and validated acquisition protocol for salivary gland scintigraphy using 99mTc-pertechnetate. RESULTS: A normal data base for both parenchymal and excretion function is given in detail. In addition, the diagnostic value of salivary gland scintigraphy is reviewed in various clinical settings, such as mild parenchymal damage in beginning Sjögren's syndrome, proof of functional obstruction in sialolithiasis with and without parenchymal damage, and parenchymal damage following radioiodine treatment. In a second part, applications of salivary gland scintigraphy in current clinical research are described, and radiation protection of salivary glands in rabbits and patients treated with high doses of I-131 are discussed. CONCLUSIONS: Salivary gland scintigraphy is a study that is easily performed and well tolerated by the patient. It yields quantitative parameters for parenchymal function and excretion fraction.

Animals↗
PubMed1997

201Tl whole-body scintigraphy in patients with malignant melanoma.

The aim of this study was to evaluate 201Tl whole-body imaging in the detection of metastases prior to surgery in patients with malignant melanoma. Whole-body imaging was performed in 30 patients with known or suspected metastases 5 and 30 min after administration of 150 MBq 201Tl. The imaging results were compared with the histopathological findings in each patient on a lesion-by-lesion basis. Of the 39 metastases proven histopathologically, 34 were detected by 201Tl imaging (sensitivity = 87%), including 4 in-transit metastases and one inguinal lymph node metastasis which were unknown prior to investigation. Due to these additional findings on 201Tl imaging, scheduled surgical therapy was changed in three patients. 201Tl imaging was false-negative in four lymph node metastases and one skin lesion, and there were two false-positive 201Tl scans with tracer accumulation in inflammatory sites. The mean target-to-background ratio on the true-positive scans was 1.72 +/- 0.37 and 1.67 +/- 0.41 (P > 0.05) at 5 and 30 min post-injection respectively. In conclusion, 201Tl whole-body imaging appears sensitive and simple to perform in the detection of metastases prior to surgery in melanoma patients.

Adult↗
PubMed1997

Ventilation scintigraphy of the middle ear.

UNLABELLED: In this study, an attempt was made to administer radioactive gas into the tympanic cavity to measure initial gas trappings as well as clearance from the middle ear to evaluate eustachian tube function. METHODS: Twenty-eight patients were administered 50 MBq 133Xe gas. Three different methods for gas application were tested: (a) direct injection through a tympanostomy tube in two patients, (b) administration through a nasopharyngeal catheter combined with Valsalva maneuvers in six subjects without middle ear dysfunction and (c) insufflation into the pharyngeal space through a nose olive performed in 12 patients with normal eustachian tube function and in eight patients with one-sided tube dysfunction. RESULTS: All three approaches were successful in visualizing middle ear ventilation, demonstrating tracer trapping within the tympanic cavities in 20 of 28 patients. Semiquantitative evaluation by region of interest techniques revealed a left-to-right uptake ratio of 48.4%-51.6% in 13 patients without tube dysfunction. Five patients with one-sided tube dysfunction showed a significantly lower median uptake of 31.6% (p = 0.01). The clearance half-lives ranged from 9 to 283 min in normal subjects and 37-64 min in patients with one-sided tube malfunction, demonstrating no statistically significant difference between the two groups and a trend towards increased washout in patients with tympanic dysfunction. CONCLUSION: Middle ear ventilation scintigraphy with 133Xe through a nose olive is an easy-to-perform test to evaluate eustachian tube function and has a success rate of about 70%, thus, reflecting the complex physiological mechanisms involved.

Adult↗
PubMed1997

[Quantitative salivary gland scintigraphy--a recommended examination prior to and after radioiodine therapy].

AIM: The aim of this study was to evaluate possible deterioration of salivary gland function due to radioiodine therapy with low activities using standardized quantitative salivary gland scintigraphy (qSZ). In addition, the prevalence of sialopathies was estimated in patients with thyroid dysfunction. METHODS: Prior to routine thyroid scintigraphy qSZ was performed after i.v. injection of 36-126 MBq 99mTc-pertechnetate, and both uptake and excretion fraction were calculated as a measure of parenchymal function and saliva excretion, respectively 312 healthy patients served as reference for a normal data base. 144 patients underwent qSZ prior to and 3 months after radioiodine therapy. Results of qSZ in another 674 thyroid patients were evaluated for determining the prevalence of salivary gland dysfunction. RESULTS: Normal uptake was 0.45 +/- 0.14% and 0.39 +/- 0.12%, and normal excretion fraction amounted to 49.5 +/- 10.6% and 39.1 +/- 9.2% in parotid and submandibular glands, respectively. Despite salivary gland stimulation with ascorbic acid during radioiodine therapy a significant activity-related functional impairment of 14-90% could be measured after application of 0.4-24 GBq of 131I. Prevalence of pretreatment sialopathies was 77/674 = 11.4% in single glands, and there was a global salivary gland functional impairment in 52/674 = 7.7%. CONCLUSION: Together with thyroid scintigraphy qSZ is an easy to perform examination without additional radiation burden. It can be recommended in all patients prior to and after radioiodine therapy both in order to quantify and to document possible parenchymal impairment induced even by low activities of 131I.

Adolescent↗
PubMed1997

Whole-body positron emission tomography (PET) for diagnosis of residual mass in patients with lymphoma.

BACKGROUND: PET using 18fluorodesoxyglucose (FDG) may offer the possibility of differentiating vital from necrotic residual masses. PATIENTS AND METHODS: Seventeen patients with HD and 17 patients with NHL underwent FDG-PET following therapy. According to staging by routine methods at diagnosis, 7 patients presented stage I, 13 stage II, 5 stage III, and 9 stage IV. A dose of 250-400 MBq FDG was injected and whole-body PET was performed 30-60 minutes later. RESULTS: Residual mass was found in 32 patients with routine methods. FDG-PET was negative in 17 patients, who were considered to be in CR. None of them relapsed (median follow-up 63 weeks ). FDG-PET was positive in 17 patients. Sixteen patients had residual mass with routine methods. Four patients received radiation after PET. Their median follow-up is 58 weeks without relapse. Two other patients with lasting CR had FDG uptake outside the residual mass--one with confirmed pneumonia. Five patients had histologically confirmed lymphoma, 2 patients relapsed according to routine methods. One patient is likely to be false positive because of fracture at lymphoma site. Seven of 10 patients with FDG uptake in the residual mass after completed therapy relapsed. According to routine restaging, 2 patients achieved CR. In 1 patient an additional focus was found in the humerus in spite of normal scintigraphy with histologically confirmed lymphoma. There were no false-negative results, but 3 false-positive results inside and 2 false-positive results outside the residual mass after completed therapy. CONCLUSIONS: PET performed for evaluation of residual mass after treatment of lymphoma has a high predictive value.

Adult↗
PubMed1996

Light elicits the release of docosahexaenoic acid from membrane phospholipids in the rat retina in vitro.

Docosahexaenoic acid is the major polyunsaturated fatty acid in photoreceptor membrane phospholipids and is thought to be necessary for photoreceptor function. Docosahexaenoic acid may be metabolized to docosanoids or, by retroconversion, to eicosapentaenoic acid followed by lipoxygenation and synthesis of n-3 metabolites. In this study we investigated the time- and illuminance-dependent release of docosahexaenoic acid from photoreceptor phospholipids in the rat retina in vitro and the effects of the phospholipase A2 inhibitor, quinacrine, on this release. Isolated rat retinae were incubated in oxygenated Ringer-Bicarbonate-Glucose-Medium and labelled with [3H]docosahexaenoic acid for 180 min in darkness. The incorporation of [3H]docosahexaenoic acid into retinal phospholipids was monitored by thin-layer chromatography. The release of [3H]docosahexaenoic acid was determined under illuminances of 100, 500, 1000, 5000 and 10,000 lx for 10 min, illuminance durations of 0.25, 2, 5 and 10 min at 10,000 lx, and with the addition of 10 and 100 mumol quinacrine to the incubation medium at 10,000 lx for 10 min. Our results demonstrate a release of docosahexaenoic acid from retinal phospholipids that is finely tuned by light levels and exposure duration. The kinetics of the time dependent docosahexaenoic acid release and the effects of quinacrine suggest that this release is mediated in part by activation of phospholipase A2. The light-elicited docosahexaenoic acid release may serve as a protective measure against formation of prostaglandins by inhibiting cyclooxygenase and by promoting the synthesis of less potent leukotrienes of the 5-series via retroconversion to eicosapentaenoic acid and 5-lipoxygenation.

Analysis of Variance↗