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O S Hoekstra

Publications and source records attributed to O S Hoekstra.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Surgery and referral for subsequent 131I therapy for patients with differentiated thyroid carcinoma in the south-east of the Netherlands, 1983-1996, compared to the consensus guidelines from 1987].

OBJECTIVE: To evaluate the treatment of patients with differentiated (papillary or follicular) thyroid cancer in general hospitals in the south-east of the Netherlands during the period 1983-1996, in relation to the 1987 national consensus recommendations. DESIGN: Population-based, retrospective, descriptive. METHOD: For the period 1 January 1983-31 December 1996, data on the histology, TNM-stage and treatment (hospital, specialist, type of operation, referral for 131I therapy) of all 236 patients with differentiated thyroid cancer were obtained from the cancer registry of the Comprehensive Cancer Centre South, Eindhoven, the Netherlands. The treatment was compared with the recommendations from the consensus meeting in 1987. RESULTS: Data on 219 patients (137 papillary, 82 follicular thyroid carcinoma) treated in the general hospitals in the region were studied; the 17 remaining patients had been referred from outside the region. Patients were treated at all hospitals in the region; the number of specialists per hospital able to treat thyroid carcinoma (internist and/or surgeon) was limited. In total 79% of the patients underwent a (near-)total thyroidectomy, half of them in two phases, and in 12% of the cases combined with regional lymph node dissection. In the majority of cases, surgical treatment was in accordance with the consensus recommendations: 65-100% of the cases per hospital. The proportion of patients referred for 131I therapy varied from 17% to 90%; referral was more frequent in the case of larger tumours and/or metastases. Of the 24 patients with a small papillary carcinoma without metastases, 79% were not referred for 131I therapy. CONCLUSIONS: The recommendations laid down in the consensus meeting in 1987 were known and appeared to be followed for surgical treatment but for subsequent 131I therapy they appeared to be interpreted differently. A review of the consensus guidelines seems to be worthwhile.

Carcinoma↗
PubMed2002

Reproducibility and clinical value of 18F-fluorodeoxyglucose positron emission tomography in recurrent melanoma.

The purpose of this study was to assess the reproducibility and clinical impact of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in patients with (suspected) recurrent melanoma. The clinical value of PET was prospectively measured in 58 consecutive patients referred for PET because of unresolved clinical questions after conventional work-up. Diagnostic understanding and therapy choice by referring physicians were evaluated before, directly after, and 6 months after PET. Observer agreement of PET readings was measured with respect to various parameters (interpretation, number and localization of lesions, 'clinically decisive' metastases), using intra-class correlation coefficients. FDG PET improved diagnostic understanding in 33 cases (57%). In six patients (10%), diagnostic understanding was solely based on PET information. According to the attending clinicians, PET contributed to a positive change of planned treatment in 23 patients (40%) and increased confidence in the chosen treatment in 23 (40%). Observer agreement of PET readings was very high (intra-class correlation coefficients were between 0.87 and 0.94). The diagnostic value related especially to the whole-body scan technique and the superior specificity, compared to conventional work-up. It is concluded that, in problematical cases with (suspected) recurrent melanoma, 18F-FDG PET had considerable impact on diagnostic understanding and management. Together with the excellent observer reliability, these results justify further studies to determine the optimal place of PET in routine diagnostic algorithms in recurrent melanoma.

Adult↗
PubMed2002

Practice, efficacy and cost of staging suspected non-small cell lung cancer: a retrospective study in two Dutch hospitals.

BACKGROUND: A study was undertaken to investigate the clinical practice, yield, and costs of preoperative staging in patients with suspected NSCLC and to obtain baseline data for prospective studies on the cost effectiveness of (18)F-fluorodeoxyglucose positron emission tomography in the management of these patients. METHODS: A retrospective study of the medical records of all patients with suspected NSCLC was performed during a 2 year interval (1993-4) in an academic and a large community hospital. RESULTS: Three hundred and ninety five patients with suspected NSCLC were identified; 58 were deemed to be medically inoperable and 337 patients proceeded to the staging process. Staging required a mean (SD) of 5.1 (1.5) diagnostic tests per patient (excluding thoracotomy) carried out over a median period of 20 days (IQR 10-31). Many of the tests (including both invasive and non-invasive) were done because previous imaging tests had suggested metastases, and in most cases the results of initial tests proved to be false positives. After clinical staging, 168 patients were considered to be resectable (stage I/II) and 144 patients underwent surgery with curative intent. At surgery 33 patients (23% of those who underwent surgery) were found to have irresectable lesions and 19 (13%) had a benign lesion. Surgery was also considered to be futile in 22 patients (15%) who developed metastases or local recurrence within 12 months following radical surgery. Hospital admission was responsible for most of the costs. CONCLUSION: In many patients staging involved considerable effort in terms of the number of diagnostic tests, the duration of the staging period and the cost, with limited success in preventing futile surgery. Failures relate to the quality of diagnostic preparation at every level of the TNM staging system.

Adult↗
PubMed2002

Failure patterns of combined modality treatment in lung cancer: the impact of staging.

BACKGROUND: Patients with locally advanced non-small cell lung cancer (NSCLC) may be treated with induction chemotherapy (IC) followed by surgery with curative intent. The impact of staging inaccuracies on the failure rate of this intensive combined modality treatment approach, i.e. non-curative chemotherapy and thoracotomy, requires further investigation. METHODS: The records of a cohort of 38 consecutive NSCLC IIIA-N2 patients treated with IC followed by surgery were reviewed. RESULTS: The clinical course strongly suggested that the standard diagnostic algorithm failed to demonstrate stage IV disease in 34% of the cases. Surgery instigated by CT-based response criteria at restaging after chemotherapy proved to be irradical in 70% of cases. CONCLUSION: Our data confirm the limitations of the current work-up of patients with apparently locally advanced NSCLC. This applies to the selection of patients to be assigned to combined modality treatment as well as to the post-chemotherapy assessment of resectability. Improved (re)staging of these patients will enhance the efficiency of intervention trials and prevent patients from being exposed to intensive and toxic therapy from which they derive no benefit.

Adult↗
PubMed2002

Rapid evaluation of FDG imaging alternatives using head-to-head comparisons of full ring and gamma camera based PET scanners--a systematic review.

AIM: While FDG full ring PET (FRPET) has been gradually accepted in oncology, the role of the cheaper gamma camera based alternatives (GCPET) is less clear. Since technology is evolving rapidly, "tracker trials" would be most helpful to provide a first approximation of the relative merits of these alternatives. As difference in scanner sensitivity is the key variable, head-to-head comparison with FRPET is an attractive study design. This systematic review summarises such studies. METHODS: Nine studies were identified until July 1, 2000. Two observers assessed the methodological quality (Cochrane criteria), and extracted data. RESULTS: The studies comprised a variety of tumours and indications. The reported GC- and FRPET agreement for detection of malignant lesions ranged from 55 to 100%, but with methodological limitations (blinding, standardisation, limited patient spectrum). Mean lesion diameter was 2.9 cm (SD 1.8), with only about 20% < 1.5 cm. The 3 studies with the highest quality reported concordances of 74-79%, for the studied lesion spectrum. Contrast at GCPET was lower than that of FRPET, contrast and detection agreement were positively related. Logistic regression analysis suggested that pre-test indicators might be used to predict FRPET-GCPET concordance. CONCLUSION: In spite of methodological limitations, "first generation" GCPET devices detected sufficient FRPET positive lesions to allow prospective evaluation in clinical situations where the impact of FRPET is not confined to detection of small lesions (< 1.5 cm). The efficiency of head-to-head comparative studies would benefit from application in a clinically relevant patient spectrum, with proper blinding and standardisation of acquisition procedures.

Equipment Design↗
PubMed2001

Systematic review of the diagnostic accuracy of (18)F-fluorodeoxyglucose positron emission tomography in melanoma patients.

BACKGROUND: Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) is a rapidly developing new imaging technique in the diagnosis and staging of melanoma. The objective of the current study was to determine the diagnostic accuracy of FDG-PET in patients with melanoma. METHODS: A systematic review and meta-analysis of clinical studies regarding FDG-PET and cutaneous melanoma was conducted. Studies were identified by a comprehensive search of the MEDLINE, EMBASE, and Current Contents databases, without any language restrictions. Eleven studies were selected. The methodologic quality of these studies was assessed independently by two reviewers. Levels of evidence and grades of recommendation were determined for each study. Six studies could be included in the statistical pooling. Sources of heterogeneity were studied by meta-regression of the diagnostic odds ratio (DOR). A summary receiver operating characteristic curve was calculated. RESULTS: The pooled sensitivity and specificity of FDG-PET in the detection of melanoma metastases were 0.79 (95% confidence interval [95% CI], 0.66-0.93) and 0.86 (95% CI, 0.78-0.95), respectively. The pooled DOR of 33.1 (95% CI, 21.9-54.0) suggests a high diagnostic accuracy for PET. Subgroup analysis revealed that PET is more accurate for systemic staging (DOR of 36.4) than for regional staging (DOR of 19.5). When used for regional staging, PET performed better in patients with American Joint Committee on Cancer Stage III disease, compared with patients with Stage I and Stage II disease. However, the methodologic quality of the studies was limited. Major problems were verification, review, and selection bias. CONCLUSIONS: Due to the poor methodologic quality of the available studies, to the authors' knowledge it is yet not possible to develop guidelines for the effective use of PET in patients with melanoma. Future accuracy studies should meet the methodologic criteria outlined in the current review.

Diagnosis, Differential↗
PubMed2001

Toward less futile surgery in non-small cell lung cancer? A randomized clinical trial to evaluate the cost-effectiveness of positron emission tomography.

Non-small cell lung cancer can be cured if the patient is medically operable and the tumor resectable. Current diagnostic strategies are aimed to detect tumor deposits that preclude resection with curative intent. However, these strategies are rather inefficient, resulting in a large number of futile invasive procedures. In the early 1990s positron emission tomography (PET) showed promising results at its introduction in the clinic, especially in oncology. A large number of accuracy studies have reported that PET is superior to conventional imaging. However, whether PET ultimately improves patient outcome should ideally be assessed by means of a randomized controlled trial. No such design has been applied to evaluate PET in oncology so far. The PLUS study was designed to compare the current strategy of conventional methods with a strategy where PET was added after completion of noninvasive techniques. Patients considered operable by the physician at this point were then randomly assigned to PET and further consequences or to standard procedures of mediastinoscopy or thoracotomy. Primary outcome events were futile thoracotomies. The trial randomized 188 patients from nine hospitals in 1 year. Patient enrollment has been stopped and data collection is in progress. The results will be published in 2001. Control Clin Trials 2001;22:89-98

Aged↗
PubMed2001

Unexplained rising carcinoembryonic antigen (CEA) in the postoperative surveillance of colorectal cancer: the utility of positron emission tomography (PET).

The aim of the study was to evaluate the use of positron emission tomography with [18F]-fluorodeoxyglucose (FDG-PET) in patients with unexplained rising carcinoembryonic antigen (CEA) in the postoperative surveillance of colorectal cancer. 50 consecutive patients with elevated CEA levels and a completely normal (n=31) or equivocal (n=19) conventional diagnostic work-up (CDW) were retrospectively selected. All PET images were reviewed with full knowledge of the CDW. The gold standard consisted of histology, or clinical follow-up of more than 1 year. Recurrent disease was established in 56 lesions in 43 patients. On a patient-based analysis, the sensitivity of FDG-PET was 34/43 (79%), and the positive predictive value 34/38 (89%). In 14/50 patients (28%), the FDG-PET findings led to a surgical resection with curative intent. On a lesion-based analysis, FDG-PET detected 42/56 lesions (sensitivity: 75%), the positive predictive value was 79% (42/53). These results demonstrate that FDG-PET can have a clear impact on patient management in patients with an unexplained elevation in CEA levels.

Adult↗
PubMed2001

Detection of osteomyelitis using FDG and positron emission tomography.

A positron emission tomography (PET) scan with 2-[fluorine-18]fluoro-2-deoxy-D-glucose ((18)FDG) was performed on a patient with clinical and laboratory signs of infection after a removed hip prosthesis but with indistinct signs on the bone scan and radiographs. The PET scan confirmed the clinical and laboratory signs and revealed an unidentified focus of infection in the distal area of the right femur.

Adult↗
PubMed2001

Diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography in the follow-up of papillary or follicular thyroid cancer.

Positron emission tomography with 18F-fluorodeoxyglucose is a relatively new nuclear imaging technique in oncology. We conducted a systematic review to determine the diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography in patients suspected of recurrent papillary or follicular thyroid carcinoma. Two reviewers independently selected, extracted, and assessed data from relevant literature found in computerized databases and by reference tracking. Prospective and retrospective studies with 10 human subjects, or more, that evaluated the accuracy of ring positron emission tomography, using 18F-fluorodeoxyglucose in follicular and papillary thyroid cancer, were included. Studies on 18F-fluorodeoxyglucose imaging using gamma cameras, reviews, case reports, editorials, letters, and comments were excluded. The methodological quality was assessed by applying the criteria for diagnostic tests recommended by the Cochrane Methods Group on Screening and Diagnostic Tests. A rating system was used for qualitative analysis consisting of four levels of evidence (1 = highest level; 4 = lowest level). Fourteen studies met the inclusion criteria. All studies claimed a positive role for positron emission tomography but, at evidence levels 3 or 4, precluding quantitative analysis. Methodological problems included poor validity of reference tests and a lack of blinding of test performance and interpretation. The reviewed material was heterogeneous with respect to patient variation and validation methodology. The most consistent data were found on the ability of 18F-fluorodeoxyglucose positron emission tomography to provide an anatomical substrate in patients with elevated serum Tg and negative iodine-131 scans. In conclusion, the results seem to support the potential of 18F-fluorodeoxyglucose positron emission tomography to identify and localize foci of recurrent cancer in the latter patient subset. However, implementation of positron emission tomography in a routine diagnostic algorithm requires additional evidence.

Adenocarcinoma, Follicular↗
PubMed2001

Technegas versus (81m)Kr ventilation-perfusion scintigraphy: a comparative study in patients with suspected acute pulmonary embolism.

UNLABELLED: 81mKr is widely used as a ventilation agent to diagnose pulmonary embolism (PE). However, (81m)Kr is expensive, which limits its continuous availability. Technegas can be an alternative ventilation agent with the advantage of being less expensive and available daily. The aim of this study was to compare the value of technegas with that of (81m)Kr in the detection of PE. METHODS: Ninety-two consecutive patients (29 men; mean +/- SD, 53 +/- 17 y old) with at least one segmental perfusion defect (Hull criteria) were studied prospectively. Perfusion and ventilation (V/Q) lung scintigraphy with both technegas and (81m)Kr were performed within 24 h on all patients. V/Q lung scan results were classified as high probability for PE (normal ventilation study) or nondiagnostic (abnormal ventilation study). All V/Q lung scans were read by two experienced nuclear physicians in consensus. For the intra- and interobserver variabilities, two experienced observers independently read the V/Q lung scans. RESULTS: (81m)Kr and technegas showed a good agreement (kappa, 0.68; 95% confidence interval [CI], 0.53-0.82). However, technegas significantly increased the number of nondiagnostic V/Q lung scans (P: = 0.035). In 15 patients, a discrepancy was found between (81m)Kr and technegas. False-positive V/Q lung scan results occurred in 4 of 12 patients (33%) with (81m)Kr and in 2 of 3 patients (66%) with technegas. The intra- and interobserver variabilities were 0.71-0.88 (95% CI, 0.56-1.0) for perfusion/(81m)Kr and 0.74-0.96 (95% CI, 0.58-1.0) for perfusion/technegas. CONCLUSION: In comparison with (81m)Kr, technegas does not result in more false-positive V/Q lung scan results. The use of technegas, however, increases the number of nondiagnostic V/Q lung scan results, which would increase the demand for further additional testing to confirm or refute PE.

Acute Disease↗
PubMed2000

[Added value of positron emission tomography with fluoro-18-deoxyglucose as the tracer (FDG-PET) in clinical problem cases in oncology].

Positron emission tomography with fluoro-18-deoxyglucose as tracer molecule (FDG-PET) is a relatively new imaging technique used in oncology to study tumour metabolism in vivo. Both qualitative and quantitative data obtained by PET provide unique information to the clinician and may guide the therapeutic approach in selected patients, where conventional diagnostic tests like CT or MRI yield equivocal results. According to the experience obtained in the Vrije Universiteit Medical Centre in Amsterdam, the additional value of FDG-PET can be explained by the sensitivity and the specificity of the technique, combined with the visualization of the whole body. FDG-PET may reveal metastases and tumour tissue may be differentiated from scar tissue and necrosis. PET is expensive and its effects on patient outcome has yet to be established.

Adult↗
PubMed2000

How to perform a comprehensive search for FDG-PET literature.

In this study, a comprehensive, unbiassed search strategy for identifying literature on fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in Medline, Embase and Current Contents was developed, with specific search strategies for each database, using MeSH terms as well as free text words for PET and FDG. To examine which text words apply to FDG, we evaluated the ways of spelling FDG in a random sample of FDG-PET articles (n = 100). These words were used as free text words in the two databases and overlap was determined. PET publications were identified using the text words "positron emission tomography" and "pet$" combined with the respective MeSH terms for each database. To compare the yield of the combined FDG-PET strategy in each database, the retrieved citations were downloaded to Pro-Cite 4.0. Finally, we added search terms for lung cancer, breast cancer, melanoma, head and neck cancer and lymphoma to our strategy and to a short strategy (consisting of the text words "positron emission tomography" and "fdg"). In order to measure the yield and precision (positive predictive value, PPV) of our search strategy and compare it with the short one, we screened the title and abstract of the retrieved citations. Reviewing a random sample of the FDG-PET literature yielded 56 different ways of spelling FDG. We confined the list to 11 text words, without missing articles. Of the publications retrieved by these text words, only 4% were indexed by the MeSH term "Fludeoxyglucose F18" in Medline and 29% by the MeSH-term "Fluorodeoxyglucose F18" in Embase. Only 51% of PET articles were indexed by the MeSH term "Tomography, emission-computed" in Medline and 40% by the MeSH term "Positron emission tomography" in Embase. The combined search strategy for identifying studies on FDG and PET resulted in 2865 publications in Medline and 2646 in Embase. Medline identified 1662 publications not found by Embase; Embase identified 1422 publications not found by Medline. Compared with the short strategy, our search strategy yielded on average 52% more publications (94%, 41% and 20% more in Medline, Embase and Current Contents, respectively). The PPV of our strategy (percent of publications that were really on PET, FDG and the specified subject) was 70%, compared with 76% using the short strategy. Regardless of the strategy used, Embase yielded more publications and was also slightly more specific than Medline. With the recommended strategy, FDG-PET publications can be identified more efficiently. We have shown the importance of searching more than one database and emphasize the use of both MeSH terms and text words in a search strategy. Standardization of the spelling of FDG and indexing of articles on FDG would substantially simplify searching.

Abstracting and Indexing↗
PubMed2000

Monitoring response to therapy in cancer using [18F]-2-fluoro-2-deoxy-D-glucose and positron emission tomography: an overview of different analytical methods.

[18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) is considered a valuable tool in the diagnosis and staging of cancer. In addition, it seems promising as a technique to monitor response to therapy. Progress is hampered, however, by the fact that various methods for the analysis of uptake of FDG in tumours have been described and that it is by no means clear whether these methods have the same sensitivity for monitoring response to treatment. As interest in monitoring response using FDG PET is growing, the danger exists that non-optimal methods will be used for evaluation. Hence an overview of the various analytical methods is given, highlighting both advantages and shortcomings of each of the methods. The ideal analytical method for response monitoring should represent an optimal trade-off between accuracy and simplicity (clinical applicability). At present, that trade-off still needs to be defined. Studies relating response, as measured with any of the available analytical methods, to outcome are urgently needed. Until then response monitoring studies should be conducted in such a way that all analytical methods can be compared with the most quantitative one, which at present is full compartmental modelling of the data.

Fluorodeoxyglucose F18↗
PubMed2000

Positron emission tomography for the detection of metastases of differentiated thyroid carcinoma.

OBJECTIVE: To show the value of positron emission tomography (PET) with 18-F-fluorodeoxyglucose (18-FDG) for the detection of metastases of differentiated thyroid carcinoma in selected patients. PATIENT HISTORIES: There were four patients, who had undergone total thyroidectomy for papillary (two) or follicular thyroid carcinoma (two). All patients had subsequent treatment with (131)iodine. Three patients had an increasing serum concentration of thyroglobulin, one patient had antibodies against thyroglobulin. A diagnostic (131)iodine scintigraphy was negative in two patients, and uncertain in two patients. Positron emission tomography was performed about 45 min after administration of 10 mCi 18-F-fluorodeoxyglucose. In three patients PET showed uptake in the cervical region, caused by lymph node metastases in two (confirmed by neck dissection) and recurrent tumor on the trachea in one patient (confirmed by surgery). In the fourth patient uptake of 18-FDG was seen in the neck and in both lungs. This led to discontinuation of treatment with (131)iodine because the lung metastases did not accumulate (131)iodine. DISCUSSION: In selected patients with differentiated thyroid carcinoma with an increasing serum concentration of thyroglobulin, PET is an important diagnostic option when scintigraphy with (131)iodine is negative or uncertain. In the four presented case histories, the results of PET led to a therapeutic decision: surgery in three patients and discontinuation of (131)iodine in one patient. The development of guidelines for the use of PET in the diagnosis of recurrent thyroid cancer is discussed.

Adenocarcinoma, Follicular↗