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Biomedical subjects

O S Hoekstra

Publications and source records attributed to O S Hoekstra.

At least 19 recordsLinked to original sources
PubMed2006

Impact of [18F]fluorodeoxyglucose positron emission tomography on surgical management of melanoma patients.

BACKGROUND: Several studies have shown adequate sensitivity and specificity of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the detection of metastases from melanoma, but few have addressed its impact on treatment. The aim of this retrospective study was to assess the impact of FDG-PET on treatment of melanoma in three Dutch university medical centres. METHODS: The medical records of 257 patients were reviewed. The indications for FDG-PET and findings were recorded. Unexpected findings of suspected (pre)malignant tumours other than melanoma were assessed. Treatment plans before and after FDG-PET were recorded and analysed to evaluate changes in disease management. RESULTS: Most scans (71.2 per cent) were requested for staging, mainly to detect distant metastases in patients with stage III disease. Overall, 56 patients (21.8 per cent) were upstaged as a result of PET. In 44 patients (17.1 per cent) treatment was changed, usually from surgery to systemic treatment in patients with stage III disease. Unexpected tumours were detected (mainly colorectal) in 11 patients (4.3 per cent). CONCLUSION: FDG-PET is most valuable in patients with stage III melanoma for detection of distant metastases and identification of candidates for surgery and/or systemic treatment. Unexpected FDG-PET findings should not be disregarded, as (pre)malignant, clinically relevant, tumours may be identified.

Adolescent↗
PubMed2005

Evaluation of pulmonary nodules: comparison of a prototype dual crystal (LSO/NAI) dual head coincidence camera and full ring positron emission tomography (PET).

PURPOSE: To determine the concordance of a prototype dual head coincidence camera (LSO-PS) and full ring PET (BGO-PET) using (18)F-fluorodeoxyglucose (FDG) in the evaluation of pulmonary nodules (PNs). MATERIALS AND METHODS: Patients referred for evaluation of < or =3 PNs (< or =3 cm diameter) were prospectively studied on the same day with both BGO-PET and LSO-PS. Imaging was performed at 60 and 120 min after injection of 370MBq FDG, respectively. Images were independently interpreted by four observers with each observer blinded to the other modality for the same patient. Lesions were scored in terms of relative intensity versus background. Non-attenuation corrected (nonAC) BGO-PET was used as the reference test. RESULTS: Forty-seven patients with 54 PNs (mean diameter 1.7 cm, S.D. 0.7) were included. Twelve nodules were in the < or =1.0 cm - 27 in the 1.1-2.0 cm - and 15 in the 2.1-3.0 cm range. Interobserver agreement was similar for both FDG imaging modalities. Using a sensitive assessment strategy with LSO-PS (> or = faint intensity deemed positive), there was a 97% (38/39, 95%CI 87-100%) concordance with BGO-PET and one false positive case with LSO-PS. Conservative reading (moderate or intense intensity deemed positive) resulted in a 92% (36/39, 95%CI 80-97%) concordance with BGO-PET, without false positives. The only lesion missed by LSO-PS using both assessment strategies involved a nodule 1.5 cm diameter that demonstrated moderate increased FDG uptake on BGO-PET. CONCLUSION: Depending on the test positivity criteria, LSO-PS demonstrates a high concordance (92-97%) with nonAC BGO-PET for the characterization of pulmonary nodules.

Aged↗
PubMed2005

Screening for distant metastases in patients with head and neck cancer: what is the current clinical practice?

OBJECTIVES: The detection of distant metastases during screening influences the choice of treatment in patients with head and neck squamous cell carcinoma (HNSCC). There is no consensus on the diagnostic technique that has to be used nor on the subgroup of HNSCC patients that may benefit from screening. DESIGN: Questionnaire on current practice concerning the diagnostic work-up in HNSCC patients for screening for distant metastases. PARTICIPANTS: Investigators in the 12 otolaryngology / head and neck and seven oromaxillofacial departments treating head and neck cancer in the Netherlands. RESULTS: The response rate was 100%. Indications for screening were cervical lymph node metastases (63%), mutilating surgery (58%), locoregional recurrence (47%), advanced T-stage (32%), second primary tumour (21%). Diagnostic techniques routinely used for screening besides chest X-ray were chest CT (84%), liver ultrasound (53%), liver CT (16%) and bone scintigraphy (42%). Forty-two per cent of the clinicians were not satisfied with the current methods of screening. CONCLUSION: This survey shows a substantial variation in indications and diagnostic techniques used for screening for distant metastases between the major institutions treating head and neck cancer in the Netherlands. There is a need for guidelines for screening for distant metastases in patients with head and neck cancer.

Bone and Bones↗
PubMed2005

Accuracy of diagnostic imaging techniques in the diagnosis of aseptic loosening of the femoral component of a hip prosthesis: a meta-analysis.

In this meta-analysis we included 32 English-language articles published between January 1975 and June 2004 on the diagnostic performance of plain radiography, subtraction arthrography, nuclear arthrography and bone scintigraphy in detecting aseptic loosening of the femoral component, using criteria based on the Cochrane systematic review of screening and diagnostic tests. The mean sensitivity and specificity were, respectively, 82% (95% confidence interval (CI) 76 to 87) and 81% (95% CI 73 to 87) for plain radiography and 85% (95% CI 75 to 91) and 83% (95% CI 75 to 89) for nuclear arthrography. Pooled sensitivity and specificity were, respectively, 86% (95% CI 74 to 93) and 85% (95% CI 77 to 91) for subtraction arthrography and 85% (95% CI 79 to 89) and 72% (95% CI 64 to 79) for bone scintigraphy. Although the diagnostic performance of the imaging techniques was not significantly different, plain radiography and bone scintigraphy are preferred for the assessment of a femoral component because of their efficacy and lower risk of patient morbidity.

Arthrography↗
PubMed2004

[18F]fluorodeoxyglucose uptake in recurrent thyroid cancer is related to hexokinase i expression in the primary tumor.

Patients suspected of recurrent differentiated thyroid cancer (DTC) may require "blind" (131)I therapy, with the disadvantage of unpredictable efficacy and toxicity. Alternatively, positron emission tomography (PET) with [(18)F]fluorodeoxyglucose ((18)FDG) can document the recurrence, thereby rationalizing therapeutic options. This study compared (18)FDG uptake in vivo with biomarkers expected to be involved in the underlying biological mechanisms. Additionally, we investigated whether such features were present in the primary tumors. Preoperatively, 19 patients with recurrent DTC underwent PET. (18)FDG uptake was compared with histological and immunohistochemical features in surgical specimens of recurrent and primary tumor. Thirteen of 19 recurrences were positive at PET, and (18)FDG uptake was associated with the expression of hexokinase type I (HK I; P = 0.011). All lesions with HK I overexpression were positive on (18)FDG PET. HK I expression in the original primary tumor and the metastases was similar in 82% (rho = 0.648; P = 0.005). In suspected recurrent thyroid cancer, stratification for (18)FDG PET may benefit from pretest immunohistochemical analysis of HK I of the primary tumor, as HK I negativity indicates a low likelihood of PET positivity.

Adult↗
PubMed2004

[Surgery and follow-up 131I therapy in patients with differentiated thyroid carcinoma in the south-east of the Netherlands, 1983-1996, compliance with the 1987 consensus guidelines: additional data].

In a previous study using data from the regional cancer registry of the Comprehensive Cancer Centre South, Eindhoven, The Netherlands, we concluded that in the majority of cases surgical treatment was in accordance with the consensus recommendations, but that about 40% of patients with differentiated thyroid cancer from a number of regional hospitals had not been referred for 131I therapy. However, in a subsequent study using patient data from these hospitals, it became clear that almost all patients had in fact been referred for therapy but to centres outside the 131I therapy region. The conclusion of the study should therefore be altered: the great majority of patients with differentiated thyroid cancer in the south-east of The Netherlands (1983-96) were referred for 131I treatment and therefore the primary surgical and the follow-up treatment complied with the 1987 consensus guidelines.

Carcinoma↗
PubMed2004

Staging in patients with locoregionally recurrent breast cancer: current practice and prospects for positron emission tomography.

The aim of this study was to describe the extent and yield of daily clinical practice when staging patients with a locoregional recurrence (LRR) of breast carcinoma and to explore the prospects for positron emission tomography (PET). The population-based Eindhoven Cancer Registry was used to select all breast cancer patients in the southeast of the Netherlands with a first episode of LRR between January 1, 1994 and June 30, 2000 (n = 175). Additional data concerning staging procedures and follow-up were collected from the medical records. Furthermore, we asked 77 physicians (response: 75%) about their opinions on staging procedures and actual treatment policy. At LRR presentation, 16% of patients were found to have distant metastases. An additional 24% were diagnosed with distant metastases within 18 months. The questionnaire revealed that 33% of clinicians thought that the sensitivity of conventional imaging techniques was too low. We tend to conclude that in daily clinical practice there is a need for more sensitive dissemination tests for patients with a LRR of breast cancer.

Adult↗
PubMed2004

Towards a minimally invasive staging strategy in NSCLC: analysis of PET positive mediastinal lesions by EUS-FNA.

STUDY OBJECTIVE: To asses the value of endoscopic ultrasound guided fine needle aspiration (EUS-FNA) in the nodal staging of patients with (suspected) non-small cell lung cancer (NSCLC) and a (18)FDG positron emission tomography (PET) scan suspect for N2/N3 mediastinal lymph node (MLN) metastases. BACKGROUND: Due to the imperfect specificity of positron emission tomography, PET positive MLN should be biopsied in order to confirm or rule out metastasis. Currently, invasive surgical diagnostic techniques such as mediastinoscopy/-tomy are standard procedures to obtain MLN tissue. The minimally invasive technique of EUS-FNA has a high diagnostic accuracy (90-94%) for the analysis of MLN in patients with enlarged MLN on computed tomography of the chest (CT). DESIGN AND PATIENTS: Thirty-six patients with proven n=26 or suspected n=10 non-small cell lung cancer and a PET scan suspect for N2/N3 lymph node metastases underwent EUS-FNA. When EUS-FNA did not confirm metastasis and the PET lesion was within reach of mediastinoscopy, a mediastinoscopy was performed. EUS-FNA negative patients with PET lesions beyond the reach of mediastinoscopy or those with a negative mediastinoscopy were referred for surgical resection of the tumour and MLN sampling or dissection. RESULTS: EUS-FNA confirmed N2/N3 disease in 25 of the 36 patients (69%) and was highly suspicious in one. In the remaining 10 patients, one PET positive and one PET negative N2 metastasis was detected at thoracotomy. The PPV, NPV, sensitivity, specificity and accuracy of EUS-FNA in analysing PET positive MLN were 100%, 80%, 93%, 100% and 94%, respectively. No complications of EUS-FNA were recorded. CONCLUSIONS AND SIGNIFICANCE: EUS-FNA yields minimally invasive confirmation of MLN metastases in 69% of the patients with potential mediastinal involvement at FDG PET. The combination of PET and EUS-FNA might qualify as a minimally invasive staging strategy for NSCLC.

Adult↗
PubMed2004

Fluorine-18 fluorodeoxyglucose positron emission tomography (PET) to detect vital retinoblastoma in the eye: preliminary experience.

BACKGROUND/AIMS: To report our first experience with FDG-PET in the detection of vital retinoblastoma. METHODS: Four newly diagnosed retinoblastoma patients, two treated retinoblastoma patients, and four control patients were enrolled in this pilot study. F18-FDG uptake was assessed in the light of clinical and histopathological features. RESULTS: PET discriminated between new patients and controls, although tumor uptake varied widely. PET added no useful information with regard to possible vital tissue in tumor scars in the eye of the two treated retinoblastoma patients. Moreover, PET findings did not correlate with clinical or histopathological features. CONCLUSION: Based on this small pilot study, F18-PET shows little promise in the detection of retinoblastoma. More research on other radiofarmacons is recommended.

Child, Preschool↗
PubMed2004

Non-invasive diagnostic work-up of patients with clinically suspected pulmonary embolism; results of a management study.

BACKGROUND: Clinicians often deviate from the recommended algorithm for the diagnosis of pulmonary embolism consisting of ventilation-perfusion scintigraphy and pulmonary angiography. OBJECTIVES: To assess the safety and feasibility of a diagnostic algorithm which reduces the need for lung scintigraphy and avoids the use of angiography. PATIENTS AND METHODS: Consecutive patients with a clinical suspicion of pulmonary embolism were prospectively investigated according to an algorithm in which the diagnosis of pulmonary embolism was excluded after a low clinical probability estimate and a normal d-dimer test result, a normal perfusion scintigraphy result, or a non-high probability scintigraphy result in combination with normal serial ultrasonography of the legs. In these patients anticoagulant treatment was withheld and they were followed up for 3 months to record possible thromboembolic events. During the study period, 923 consecutive patients were seen, of whom 292 were excluded because of predefined criteria. RESULTS: Of the 631 included patients, the diagnosis was refuted on the basis of a low clinical probability estimate and a normal d-dimer test result (95 patients), normal perfusion scintigraphy (161 patients) and non-high probability lung scintigraphy followed by normal serial ultrasonography (210 patients). Of these 466 patients, venous thromboembolic complications during follow-up occurred in six (complication rate 1.3%, 95% confidence interval 0.5, 2.8). The diagnostic protocol was completed in 92% of all included patients. CONCLUSION: The diagnosis of pulmonary embolism can be safely ruled out by a non-invasive algorithm consisting of d-dimer testing combined with a clinical probability estimate, lung scintigraphy, or serial ultrasonography of the legs (in case of non-diagnostic lung scintigraphy).

Algorithms↗
PubMed2004

In search of an unknown primary tumour presenting with extracervical metastases: the diagnostic performance of FDG-PET.

A retrospective study was carried out to determine the performance of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with unknown primary tumours presenting with metastases external to the neck. All patients referred to an academic PET centre (July, 1997 to December, 2000) presenting with an extracervical metastasis and no prior systemic therapy were eligible. The minimum follow-up period was 11 months. From 63 eligible cases, known metastases were FDG avid in all but one neuroendocrine process. PET scans were retrospectively classified as positive for a primary tumour (n=29), i.e. revealing at least one anatomical site suspected to be the primary tumour. This was confirmed in 16, either by histology (n=10) or radiological and clinical follow-up (n=6). There were four false positive cases. In nine patients, the primary tumour was never confirmed. Of the remaining 33 negative PET scans the primary tumour was clinically not found in 18. Follow-up and additional pathology investigations demonstrated the primary tumour in 15. A survey on clinical usefulness of PET (response rate 83%) suggested that PET positively contributed to diagnostic understanding in 29 of 52 evaluable cases. Applied late in the diagnostic trajectory, approximately four patients need to be scanned by PET in order to find one primary tumour. However, in addition to direct demonstration of unknown primaries, there appears to be a positive effect on the diagnostic work-up of these patients of a similar magnitude.

Adult↗
PubMed2003

The value of [18F]fluoro-2-deoxy-D-glucose positron emission tomography in the selection of patients with stage IIIA-N2 non-small cell lung cancer for combined modality treatment.

Combined modality treatment (CMT) for patients with stage IIIA-N2 non-small cell lung cancer (NSCLC) is at present studied extensively. To select patients with truly stage IIIA-N2 disease, however, proves to be difficult with current diagnostic tests. Distant metastases may become clinically overt during induction chemotherapy (IC) or shortly after, revealing the inaccuracies of current staging algorithms. A prospective study with [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) in IIIA-N2 NSCLC patients was performed to assess its value in the selection of this patient group. Fifty-seven patients received a whole body FDG PET scan as part of an ongoing response monitoring trial. Results were compared with conventional staging. In 32/57 (56%) PET suggested upstaging, which was confirmed in 17/57 (30%) with a median follow-up of 16 (range 2-49) months. These results show that using the conventional staging algorithm a substantial group of patients was understaged. FDG PET improves the selection of patients suitable for CMT.

Adenocarcinoma↗
PubMed2003

Feasibility of a randomized trial on adjuvant radio-iodine therapy in differentiated thyroid cancer.

BACKGROUND: Justification for adjuvant radio-iodine (I-131) therapy in differentiated thyroid cancer (DTC) is purely based on retrospective data. This is true for ablative therapy and even more so for high-dosage adjuvant schedules. Randomized trials on the latter application are considered impossible due to anticipated formidable sample sizes required in a disease with an overall excellent prognosis like DTC. OBJECTIVE: To develop and validate a model that could stratify for risk of recurrence, rather than survival, as is usually done in prognostic indices, and secondly, to use this model to estimate the sample size required for a randomized trial. DESIGN, PATIENTS AND RESULTS: From databases of three large Dutch centres, we identified 342 consecutive patients without known residual DTC after (near-) total thyroidectomy. Using Cox proportional hazards analysis, a model was validated that clearly distinguished risk categories of recurrence using commonly available baseline variables. The model included age, N stage at presentation and T stage in papillary carcinoma. According to this stratification, a subset of patients at substantial risk for relapse (30-40%) was identified. They could be eligible for a trial assessing the impact of high-dose adjuvant I-131 on recurrence rates. Assuming a clinically relevant effect of 30% reduction of relapses, 290 patients would have to be entered in either arm (alpha 0.05, power 80%). CONCLUSION: We conclude that even though a randomized trial on this issue will be difficult to design and conduct, sample size is not the main problem.

Adult↗
PubMed2003

How morphometric analysis of metastatic load predicts the (un)usefulness of PET scanning: the case of lymph node staging in melanoma.

BACKGROUND: In primary cutaneous melanoma, the sentinel node (SN) biopsy is an accurate method for the staging of the lymph nodes. Positron emission tomography (PET) has been suggested as a useful alternative. However, the sensitivity of PET may be too low to detect SN metastases, which are often small. AIM: To predict the value of PET for initial lymph node staging in melanoma based on morphometric analysis of SN metastatic load, without exposing patients to PET. MATERIALS AND METHODS: In 59 SN positive patients with melanoma, the sizes of tumour deposits in the SNs and subsequent dissection specimens were measured by morphometry and correlated with the detection limits of current and future PET scanners. RESULTS: The median tumour volume within the basin was 0.15 mm(3) (range, 0.0001-118.86). Seventy per cent of these deposits were smaller than 1 mm(3). State of the art PET scanners that have a resolution of about 5 mm would detect only 15-49% of positive basins. Logistic regression analysis revealed no pretest indicators identifying patients expected to have a positive PET. However, the SN tumour load was a significant and single predictor of the presence of PET detectable residual tumour. CONCLUSION: Morphometric analysis of metastatic load predicts that PET scanning is unable to detect most metastatic deposits in sentinel lymph nodes of patients with melanoma because the metastases are often small. Therefore, the SN biopsy remains the preferred method for initial regional staging.

Adolescent↗
PubMed2003

Prospective use of serial questionnaires to evaluate the therapeutic efficacy of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in suspected lung cancer.

BACKGROUND: A study was undertaken to study the effect of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) on the diagnosis and management of clinically problematic patients with suspected non-small cell lung cancer (NSCLC). METHODS: A prospective before-after study was performed in a cohort of all 164 patients (university/community settings) referred for PET between August 1997 and July 1999. PET was restricted to cases where non-invasive tests had failed to solve clinical problems. The impact on diagnostic understanding and management was assessed using questionnaires (intended treatment without PET, actual treatment choice after PET, post hoc clinical assessment). RESULTS: Diagnostic problems especially pertained to unclear radiological findings (n=112; 63%), mediastinal staging (n=36; 20%), and distant staging issues (n=16; 9%). PET findings were validated by reviewing medical records. PET had a positive influence on diagnostic understanding in 84%. Improved diagnostic understanding solely based on PET was reported in 26%. According to referring physicians, PET resulted in beneficial change of treatment in 50%. Cancelled surgery was the most frequent change in treatment after PET (35%). CONCLUSION: FDG PET applied as "add on" technology in patients with these clinical problems appears to be a clinically useful tool, directly improving treatment choice in 25% of patients. The value of increased confidence induced by PET scanning requires further evaluation.

Carcinoma, Non-Small-Cell Lung↗