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C Schiepers

Publications and source records attributed to C Schiepers.

At least 19 recordsLinked to original sources
PubMed2001

Decision analysis for the cost-effective management of recurrent colorectal cancer.

OBJECTIVE: To determine whether the use of [(18)F]2-fluoro-2-deoxyglucose positron emission tomography (FDG PET) in addition to computed axial tomography (CT) is helpful in managing recurrent colorectal cancer (CRC). SUMMARY BACKGROUND DATA: There is no consensus on a management algorithm for CRC. However, when recurrence is suspected, CT is generally used for further evaluation and staging of disease. METHODS: The authors used decision trees based on theoretical models to assess the cost-effectiveness of a CT + FDG PET strategy for the diagnosis and management of recurrent CRC compared with a CT-alone strategy. These theoretical models focus on patients with hepatic recurrence who are potentially curable through surgical hepatic resection. The population entering the decision trees consisted of patients with CRC who had undergone surgical resection of their primary CRC and who were suspected of having recurrence based on elevated levels of carcinoembryonic antigen. RESULTS: The CT + FDG PET strategy was found to be cost-effective for managing patients with elevated carcinoembryonic antigen levels who were candidates for hepatic resection. The CT + FDG PET strategy was higher in mean cost by $429 per patient but resulted in an increase in the mean life expectancy of 9.527 days per patient. CONCLUSIONS: These results show, through rigorous decision tree analysis, the potential cost-effectiveness of FDG PET in the management of recurrent CRC. The decision trees can be used to model various features of the management of recurrent CRC, including the cost-effectiveness of other newly emerging technologies.

Colorectal Neoplasms↗
PubMed2001

Surgical correction of vesicoureteral reflux: 5-year follow-up with 99Tcm-DMSA scintigraphy.

AIM: To evaluate kidney function before and after surgical correction of vesicoureteral reflux. The long-term effect was measured with quantitative nephro-scintigraphy using 99Tcm labelled dimercaptosuccinic acid (99Tcm-DMSA). METHODS: Forty-five children with a history of urinary tract infections due to vesicoureteral reflux (VUR) were studied. VUR grade was determined with contrast voiding cystourethrography. Planar scintigraphy was performed with 99Tcm-DMSA and uptake measured as a percentage of injected dose. Kidney function was evaluated at baseline and 5 years after corrective surgery. RESULTS: Three months after surgery, persistent mild reflux was found in eight of 76 treated renal units. Kidney uptake at 5-year follow-up was unchanged in the majority of children, indicating preservation of renal function found at baseline. The split renal function showed an excellent correlation (r = 0.99) between baseline and follow-up studies (regression slope 1.01). Percentage uptake had a regression slope of 0.89 significantly different from unity (P<0.05). Empirical kidney-depth correction techniques were compared. The scintigraphic pattern worsened in six kidneys, indicative of increased scarring in a minority of children. CONCLUSION: Planar nephro-scintigraphy with 99Tcm-DMSA was well tolerated in our paediatric population, and appeared appropriate to evaluate kidney function in time. After surgical correction of VUR, the baseline function was maintained in 94% of kidneys.

Adolescent↗
PubMed2001

Impact of 18F-FDG PET on managing patients with colorectal cancer: the referring physician's perspective.

UNLABELLED: Whole-body PET imaging with 18F-FDG has been used successfully to stage colorectal cancer. However, the impact of FDG PET on patient management from the referring physician's point of view has not been determined. METHODS: A questionnaire was sent to referring physicians to determine whether and how PET altered the management of colorectal cancer patients. Management changes, when present, were classified as intermodality (e.g., medical to surgical, surgical to radiation, medical to no treatment) or intramodality (e.g., altered medical, surgical, or radiotherapy approach). RESULTS: Of 60 responses from referring physicians, changes in clinical stage were reported for 25 patients (42%). Among these, the disease was upstaged in 20 patients (80%) and downstaged in 5 patients (20%). The PET findings contributed to intermodality management changes in 22 of the 60 patients (37%), intramodality changes in 11 patients (18%), a combination of management changes in 4 patients (7%), and no change in 19 patients (32%). Two of the 60 patients (3%) had other changes, and no response to this question was received for the remaining 2 patients (3%). As a result of PET findings, physicians avoided major surgery in 41% of patients for whom surgery was the intended treatment. CONCLUSION: This survey-based study of referring physicians shows that FDG PET had a major impact on the management of colorectal cancer patients and contributed to changes in clinical stage and major management decisions in >40% of patients.

Adult↗
PubMed2001

Impact of whole-body 18F-FDG PET on staging and managing patients with breast cancer: the referring physician's perspective.

UNLABELLED: FDG PET has emerged as an important clinical imaging modality for diagnosing and staging cancer. However, the impact of FDG PET on staging and managing patients with breast cancer from the referring physician's point of view is unknown. METHODS: The referring physicians of 160 breast cancer patients received standardized questionnaires inquiring if and how PET findings altered their patient's stage and their clinical management decisions. Management changes were classified as intermodality if the change was from one modality to another (e.g., medical to surgical, surgical to radiation, medical to no treatment, and vice versa) or as intramodality if the change was within the same modality (e.g., altered medical or radiotherapy approach). RESULTS: Fifty of the 160 surveys were completed (31% response rate). PET changed the clinical stage in 36% of patients (28% upstaged, 8% downstaged) and resulted in intermodality changes in 28% of patients and intramodality changes in 30% of patients. CONCLUSION: The results of this prospective survey show that FDG PET has a major impact on the management of breast cancer patients, influencing both clinical stage and management in more than 30% of patients.

Adult↗
PubMed1999

The effect of preoperative radiation therapy on glucose utilization and cell kinetics in patients with primary rectal carcinoma.

BACKGROUND: Proliferating cells in neoplasms usually show rapid cell cycle times and high rates of glycolysis. Tumor glucose utilization (TuGluc), potential cell doubling time (Tpot), and the effect of radiotherapy (RT) were evaluated in patients with primary rectal carcinoma. METHODS: 2-[18F]-fluoro-2-deoxy-glucose (18F-FDG) was administered and dynamic positron emission tomography (PET) performed to determine TuGluc. Cell kinetics were measured with flow cytometry after labeling with iodo-deoxy-uridine. Two groups of patients were investigated prospectively: 1) those patients undergoing surgery only and 2) those patients undergoing surgery after receiving 30 gray of RT. Twenty consecutive patients with a cT3-NX-M0 tumor and age > 50 years were selected and randomized. One patient was excluded because of unexpected liver metastases and another had incomplete data. RESULTS: At baseline, the TuGluc for Group 1 was 222+/-104 nmol/mL/minute (mean +/- 1 standard deviation), and was 215+/-126 nmol/mL/minute for Group 2 (P > 0.8). After RT TuGluc decreased to 77+/-39 nmol/mL/minute (P = 0.008). Tpot was 3.4+/-1.2 days for Group 1 and 2.6+/-2.0 days for Group 2 at baseline (P > 0.2). Two weeks after RT, Tpot slowed to 5.7+/-3.6 days (P = 0.04). A weak negative correlation (correlation coefficient = -0.36) was found between TuGluc and Tpot. After RT, the proportion of labeled cells had not changed from baseline levels (P > 0.2), suggesting undisturbed proliferation, but the DNA synthesis time had increased. The significant decrease of TuGluc indicated cell loss. CONCLUSIONS: Tumor FDG uptake and cell kinetics are not correlated strongly in rectal carcinoma. Preoperative RT results in an overall loss of tumor cells (tumor reduction) and an increase in Tpot, although proliferation of the viable cell fraction is maintained.

Cell Cycle↗
PubMed1999

18-FDG imaging in breast cancer.

Despite the large number of women with breast cancer and the importance of this disease in health care, only a relatively small number of published reports involve the application of 18-fluorodeoxyglucose (FDG) in the evaluation of patients with breast cancer. This report summarizes the results of these studies, presents the opinions from various clinical oncologists from both a university and community setting, and discusses the possible future implication of positron imaging technology in the management of breast cancer. The four potential areas of clinical application include (1) detection and differentiation of primary breast lesions, (2) staging of axillary lymph nodes, (3) detection of residual and metastatic disease, and (4) monitoring the response to chemotherapy.

Breast Neoplasms↗
PubMed1998

Positron emission tomography as a diagnostic tool in oncology.

Early diagnosis in oncology is important for treatment by surgical intervention, which generally has the highest curative potential. For higher stages of disease involvement, initiation of rapid treatment is indicated to provide the patient with the optimal therapy regimen. Although this may not improve the prognosis, it will maintain the quality of life. Anatomic imaging modalities, such as CT, MR imaging, and US, are clinically important high-resolution imaging techniques that are well suited to reveal structural abnormalities. However, the differentiation of lesions as being benign or malignant is still problematic. Metabolic imaging modalities in nuclear medicine (NM), i.e., single photon emission computed tomography (SPECT) and positron emission tomography (PET), can reveal biochemical parameters of the lesions such as glucose, oxygen, or amino acid metabolism, or measure the receptor density status. These parameters may allow a completely new clinical perspective in the management and understanding of diseases such as cancer. Although PET has been around since the early 1960s, it has only recently emerged as a powerful diagnostic tool in oncology. Society has great difficulty accepting this clinical imaging modality because of its high cost and complexity. Current applications of PET in oncology have been in characterizing lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and therapy monitoring. Here, the role of PET in diagnosis, staging, and restaging of cancer is reviewed and compared with the other tumor imaging modalities. We cover articles published in the past 3 years. We utilize the typical radiology format, in which the contribution in each body area is reviewed (topographic orientation), instead of the more organ-based approach used in internal medicine.

Biomarkers, Tumor↗
PubMed1998

Measurement of skeletal flow with positron emission tomography and 18F-fluoride in femoral head osteonecrosis.

Positron emission tomography (PET) with 18F-fluoride was utilized to determine the regional blood flow to the femoral head in early osteonecrosis. Five patients with a history of unilateral hip trauma and a normal contralateral side were selected. Skeletal flow and fluoride uptake in the abnormal and normal hips were compared directly, and the relation between bone blood flow and final outcome, i.e., surgical replacement or conservative treatment, was evaluated. In this pilot study, a flow ratio of at least 2 between the abnormal and normal femoral head was necessary to predict a successful outcome with a conservative regimen. A minimum flow of 0.04 ml/min/ml was measured in one patient whose affected femoral head healed conservatively. Our preliminary study indicates that this type of highly technical investigation appears feasible in clinical practice and permits prediction of the outcome depending upon regional skeletal flow measurements in vivo.

Adult↗
PubMed1998

Evaluating tumor biology and oncological disease with positron-emission tomography.

The usefulness of positron-emission tomography (PET) for noninvasive assessment of several biological parameters of neoplastic tissue has been reviewed. Numerous radiotracers have been developed, whose particular distribution in the presence of cancer in vivo serves to distinguish medically relevant properties of the tumor cells with which they associate. That distribution is most accurately determined through use of a PET scanner, to localize and quantify the tracer molecules, in which have been incorporated positron-emitting isotopes. These tracers include hypoxia markers, receptor ligands, substrates for enzymatic modification by the products of expression of specific genes, and precursors of protein anabolism and carbohydrate catabolism. In addition, application of PET to evaluation of patients with some particular cancers has been examined, while placing special emphasis on the level of scientific rigor of the evidence underlying conclusions about appropriate use of PET in oncology.

Biology↗
PubMed1998

Three-phase bone scan and dynamic vascular scintigraphy in algoneurodystrophy of the upper extremity.

UNLABELLED: Algoneurodystrophy (AND) is a complex disorder with a wide spectrum of clinical presentations. Patients referred for a work-up of unilateral upper extremity AND were reviewed, and 50 patients were enrolled with sufficient documentation on history, causal event, clinical stage, and final outcome. There were 27 females, 23 males, mean age 44 years. The affected area was: shoulder 5, arm 3, elbow 3, wrist 26 and hand 13. Main precipitating events were fracture, contusion, or prior surgery. Three-phase bone scintigraphy was performed followed by a 2-phase vascular scintigraphy on another day. Typical periarticular uptake on the delayed bone scan was used to diagnose AND. Staging was done with the dynamic phase of the vascular scan. The clinicians diagnosed 30 patients positive for AND, 14 negative, and 6 equivocal. Bone scintigraphy yielded 25 positive, 20 negative, and 5 equivocal scans, i.e. sensitivity 73% and specificity 86%. Of the positive bone scans, 21 had all 3 phases positive, and 16 were concordant on vascular scintigraphy. The remaining 5 vascular scans classified 3 patients in transition (stage I-->II) and 2 in stage II. In other words, in 24% of patients vascular scintigraphy indicated restaging. CONCLUSION: dynamic bone scintigraphy is an accurate method to diagnose AND. Vascular scintigraphy changed AND stage in one quarter of the patients. Therefore, a combination of both studies is indicated in the work-up and treatment monitoring of AND.

Adult↗
PubMed1997

Picture archiving and communication system-asynchronous transfer mode network in a midsized hospital.

This article describes the pathway to full implementation of a hospital information system-picture archiving and communication system-wide area network (HIS-PACS-WAN) in a 300-bed acute care hospital, and the linking of that system to two other off-site medical centers. The PACS included direct digital capture of computed tomography (CT), magnetic resonance (MR) imaging, nuclear medicine, and ultrasonography images into an Olicon archive. Plain radiographs and fluoroscopy images were digitized manually and archived into an Olicon system. The active archive included current images on each Olicon workstation and the juke box. Long-term archiving of the images on removable optical discs, which would be loaded manually by an operator every time a request for one of these studies appeared on the operator's monitor, also was implemented. Ability to store, retrieve, and display simultaneously the physician's report of each procedure along with the images was an ultimate goal. The WAN is to be used for teleradiology and teleconferencing among the three medical centers involved in this study as well as other off-site locations. Phase I included the design and installation of the local area network (LAN) in the Department of Radiology at Olive View-UCLA Medical Center. This included the clinics and the inpatient and hospital-wide fiber-optic network and its linkage to the local telephone company. Phase II involved linkage of the Olicon workstations to imaging equipment. This implementation has been delayed significantly because of inadequate needs assessment, absence of planning for forward-compatibility to imaging equipment, and incompatibilities in DICOM conformance among vendors. Every PACS project must include an in-depth needs analysis, which should be updated yearly because of rapid turnover of technology. Although this analysis should have a heavy emphasis on clinical needs, it must incorporate the hospital-wide needs for an integrated information systems network. Integration of PACS, HIS, RIS, and a dictation/transcription system is a complex task that requires a full-time, clinically oriented project officer for successful completion.

Computer Communication Networks↗
PubMed1997

PET in oncology: will it replace the other modalities?

Medical imaging technology is rapidly expanding and the role of each modality is being redefined constantly. PET has been around since the early sixties and gained clinical acceptance in oncology only after an extreme number of scientific publications. Although PET has the unique ability to image biochemical processes in vivo, this ability is not fully used as a clinical imaging tool. In this overview, the role of PET in relation to other tumor imaging modalities will be discussed and the reported results in the literature will be reviewed. In predicting the future of PET, technical improvements of other imaging modalities need to be dealt with. The fundamental physical principles for image formation with computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), photon-emission tomography (PET), and single photon emission CT (SPECT) will not change. The potential variety of radiopharmaceuticals which may be developed is unlimited, however, and this provides nuclear imaging techniques with a significant advantage and adaptive features for future biologic imaging. The current applications of PET in oncology have been in characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. The articles discussed in this review were selected from a literature search covering the last 3 years, and in which comparisons of PET with conventional imaging were addressed specifically. PET studies with the glucose analogue fluorine-18-labeled deoxyglucose (FDG) have shown the ability of detecting tumor foci in a variety of histological neoplasms such as thyroid cancer, breast cancer, lymphoma, lung cancer, head and neck carcinoma, colorectal cancer, ovarian carcinoma, and musculoskeletal tumors. Also, the contribution of the whole body PET (WBPET) imaging technique in diagnosis will be discussed. In the current health care environment, a successful imaging technology must not only change medical management but also demonstrate that those changes improve patient outcome.

Adrenal Gland Neoplasms↗
PubMed1997

Role of positron emission tomography in the staging of lung cancer.

Early detection and staging of lung cancer is important in initiating rapid treatment and improving prognosis. Computed tomography (CT) and magnetic resonance (MR) imaging have a high resolution and are able to reveal structural abnormalities, but still have problems differentiating benign from malignant lesions. Lesion size is used as a distinguishing parameter but definite diagnosis still relies on invasive procedures. Positron emission tomography (PET) is based on imaging of biochemical processes in vivo. PET is unique by disclosing metabolic differences between benign and malignant disease, e.g. glucose utilization. Here, the role of PET in diagnosis and (re)-staging of lung cancer as well as monitoring of therapy response will be reviewed.

Carcinoma, Non-Small-Cell Lung↗
PubMed1997

Positron emission tomography, magnetic resonance imaging and proton NMR spectroscopy of white matter in multiple sclerosis.

OBJECTIVE: To assess characteristics of MS lesions and normal appearing white matter (NAWM) with various imaging modalities. Glucose metabolism was investigated with FDG-PET, metabolite concentration with proton NMR spectroscopy, and lesion detection with routine brain MRI. METHODS: Thirteen patients were studied in a stable phase of their disease, and two during an acute episode. Nine healthy volunteers served as controls. RESULTS: Three patients had a normal brain MRI, 12 had typical lesions. MR images were registered to the PET planes. Lesions and contra-lateral control areas were analyzed, 10/15 lesions showed relative hyper-metabolism and 2 hypo-metabolism. NAA concentration was significantly decreased in both lesions and NAWM. CONCLUSION: In stable MS, most large lesions have a relatively increased glucose utilization and decreased NAA concentration. NAWM showed a significantly decreased NAA concentration compared to healthy subjects, but no difference in glucose metabolism. Active lesions in acute MS are also hyper-metabolic. This finding opens a new window on the classification of white matter lesions based on glucose utilization.

Acute Disease↗
PubMed1997

Normal brain perfusion pattern of technetium-99m-ethylcysteinate dimer in children.

UNLABELLED: The purpose of this study was to assess the normal perfusion pattern of the pediatric brain with 99mTc-ethylcysteinate dimer (99mTc-ECD). METHODS: Tomographic imaging was performed with a dedicated system with high sensitivity and resolution. Sixteen children, referred for brain imaging in the workup of seizure disorder, were included since they turned out negative after a 1-yr follow-up. A standardized brain presentation was obtained after reslicing and reorienting of the three-dimensional volumetric dataset. RESULTS: Quantitative analysis did not reveal significant left-right uptake differences per patient. Three age clusters were investigated that showed differences in regional uptake, mainly a relatively increased uptake in basal ganglia, visual and motor cortex. An uptake ratio or perfusion index was calculated after normalization. Normal limits were established for the children in the three groups. CONCLUSION: Technetium-99m-ECD is a safe agent for children and should be the radiopharmaceutical of choice for brain perfusion studies because of favorable radiation dosimetry and stability. The age dependence of perfusion necessitates a database comparison before concluding that the observed perfusion pattern is normal.

Adolescent↗
PubMed1997

Clinical value of dynamic bone and vascular scintigraphy in diagnosing reflex sympathetic dystrophy of the upper extremity.

The role of planar dynamic scintigraphy in the diagnosis and staging of reflex sympathetic dystrophy (RSD) is presented. Bone and vascular tracers are used for this purpose. The bone scan assessment corresponded closely to the clinical diagnosis and appeared excellent to exclude RSD. Accurate staging is important for therapy decisions. Staging by the early phases of bone and vascular scans were concordant in about three quarters of patients, but vascular scintigraphy led to a restaging in the remaining quarter of patients. Both scintigraphic procedures (bone and vascular) are indicated in diagnosing and monitoring upper extremity RSD.

Adult↗
PubMed1997

Fluoride kinetics of the axial skeleton measured in vivo with fluorine-18-fluoride PET.

UNLABELLED: The aim of this study was to quantify regional bone blood flow and influx rate with PET and [18F]fluoride in patients with metabolic bone disorders. METHODS: Dynamic imaging of the spine or pelvis was performed after administration of 300-370 MBq of 18F-. Plasma clearance of 18F- was determined in blood sampled from the radial artery. A three-compartment model was used to estimate the regional flow and fluoride influx rate. RESULTS: In this preliminary study, fluoride flux (in micromol/min/liter) could be measured regionally. The flux was consistent with the pathophysiology of the studied metabolic disorders and allowed the various disease states to be distinguished. Bone blood flow and influx rate were low in osteoporosis (in the "normal-appearing" bone) and high in Paget's disease. CONCLUSION: With PET and [18F]fluoride, local bone blood flow and fluoride influx rate can be quantified in patients in vivo. Metabolically active zones have an increased influx rate and an accordingly increased flow. In principle, this technique permits classification of bone disorders and has potential for the monitoring of therapy response in metabolic bone disease.

Adult↗