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At least 127 records · Page 7Linked to original sources
PubMed1991

Cone beam tomography of the heart using single-photon emission-computed tomography.

The authors evaluated cone beam single-photon emission-computed tomography (SPECT) of the heart. A new cone beam reconstruction algorithm was used to reconstruct data collected from "short scan" acquisitions (of slightly more than 180 degrees) of a detector anteriorally traversing a noncircular orbit. The less than 360 degrees acquisition was used to minimize the attenuation artifacts that result from reconstructing posterior projections of 201T1 emissions from the heart. The algorithm includes a new method for reconstructing truncated projections of background tissue activity that eliminates reconstruction ring artifacts. Phantom and patient results are presented which compare a high-resolution cone beam collimator (50-cm focal length; 6.0-mm full width at half maximum [FWHM] at 10 cm) to a low-energy general purpose (LEGP) parallel hole collimator (8.2-mm FWHM at 10 cm) which is 1.33 times more sensitive. The cone beam tomographic results are free of reconstruction artifacts and show improved spatial and contrast resolution over that obtained with the LEGP parallel hole collimator. The limited angular sampling restrictions and truncation problems associated with cone beam tomography do not deter from obtaining diagnostic information. However, even though these preliminary results are encouraging, a thorough clinical study is still needed to investigate the specificity and sensitivity of cone beam tomography.

Algorithms↗
PubMed2004

Preoperative detection of liver metastases secondary to pancreatic cancer: utility of combined helical computed tomography during arterial portography with biphasic computed tomography-assisted hepatic arteriography.

OBJECTIVE: This study was designed to define the diagnostic advantage of computed tomography during arterial portography combined with computed tomography-assisted hepatic arteriography ( CTAP + CTHA) for preoperative detection of liver metastases secondary to pancreatic cancer compared with that of multidetector computed tomography (MDCT). METHODS: From January 2002 to February 2003, we retrospectively studied 19 consecutive patients with pancreatic cancer. MDCT was performed on all patients prior to preoperative visceral angiography. Fourteen patients underwent CTAP + CTHA at the time of preoperative angiography. RESULTS: Liver metastases were identified in 3 patients by means of MDCT. Of 14 patients who underwent CTAP + CTHA, 8 patients (57.1%) were diagnosed as having liver metastases, which could not be detected by MDCT. These tumors missed by MDCT ranged from 5 to 15 mm in size. On CTAP + CTHA, a single nodule in the liver was detected in 2 patients, 2 nodules in 2 patients, 3 lesions in 1 patient, and > or =4 lesions in 3 patients. The sensitivity and specificity of CTAP + CTHA versus MDCT were 75.0% versus 23.1% and 66.7% versus 100%, respectively. CONCLUSIONS: In conclusion, the combination of CTAP and CTHA is useful to confirm liver metastases before operation for resectable pancreatic cancer because it has higher sensitivity to detect of liver metastases compared with MDCT.

Adenocarcinoma↗
PubMedDate not supplied

Angiographic computed tomography is comparable to multislice computed tomography in lumbar myelographic imaging.

We evaluated the feasibility of angiographic computed tomography (ACT) for diagnostic imaging in a patient with degenerative lumbar spine disease. ACT provides a volume data set out of a rotational acquisition with a c-arm-mounted flat-panel detector. Using this technique, radiographic myelography and myelographic computed tomography can be performed in a single session at the same imaging system. The quality of the reconstructed ACT slice images is comparable to those acquired by postmyelographic computed tomography.

Aged↗
PubMed1999

[Detection of malignant focal hepatic lesions. Comparison of ultrasonography, computerized tomography during arterial portography, delayed computerized tomography and magnetic resonance imaging].

AIMS: This study was performed to compare the sensitivity of ultrasonography, computerized tomography during arterial portography, delayed computerized tomography, and magnetic resonance imaging to detect focal liver lesions. Forty three patients with primary or secondary malignant liver lesions were studied prior to surgical intervention. METHODS: The results of the imaging studies were compared with intraoperative examination of the liver, intraoperative ultrasonography and pathology results (29 patients). In the non-operated (14 patients) group, we compared the number of lesions detected by each technique. RESULTS: One hundred and forty six lesions were detected. There was 84% sensitivity with computerized tomography during arterial portography, 61.3% with delayed scan, 63.3% with magnetic resonance imaging and 51% with ultrasonography in operated patients. In patients who did not undergo surgery, magnetic resonance imaging was more sensitive in detecting lesions. CONCLUSIONS: In operated and non-operated patients series, CT during arterial portography had the highest sensitivity, but magnetic resonance imaging had the most consistent overall results.

Adult↗
PubMed1995

[Producing the third dimension of flat radiographic images: analogue tomography - computer tomography].

The inventor of computer tomography, Godfrey N. Hounsfield, mentioned in his Nobel Foundation lecture the following three main problems of conventional radiography: 1. It depicts the sum of shadows from several tissue elements at the same spot of the film. 2. The sensitivity of the employed photographic medium does not allow to differentiate between various soft tissue densities. 3. It gives no exact measure characterizing tissue densities. The first part of this article is dealing with the solution of problem number one. Researchers within medical imaging from many countries developed independently of each other a variety of methods for body-sectional imaging methods, but he did not construct any equipment. Alessandro Vallebona constructed equipment and published the first clinical body-section imaging material ever in 1930, but his method was not ideal. The first clinical material employing an ideal method was published by Bernhard Ziedses des Plantes in 1932. Methods for transverse axial tomography was independently described by William Watson in 1937, Jean Kieffer in 1938, and Shinji Takahashi in 1947. The limitation in sensitivity of the photographic medium was revealed in parallel to this development. In 1963 Allan M. Cormack described the mathematical model for absorption of ionizing rays in inhomogenous tissue. Godfrey N. Hounsfield combined this knowledge of mathematics with the fast developing computer technology and the medical need for a more sensitive registration medium. In 1971 computer tomography was a reality. One of the greatest conquests in medicine of this century had been made. Recent developments within scanner technology predict still better and safer diagnostic possibilities.

History, 20th Century↗
PubMed2003

[Is coincidence detection emission tomography (CDET) as reliable as positron emission tomography (PET) in head and neck cancer?].

OBJECTIVE: Positron emission tomography (PET) is becoming more and more useful in head and neck tumour detection, guiding diagnostic and therapeutic decision. However, techniques, similar to PET, but using modified conventional tomography equipment, are used. The most commonly used is the dual-head positron emission tomography using coincidence detection (CDET). This study was aimed at searching if CDET could be as reliable as PET in some of its indications. PATIENTS AND METHODS: Between 1997 and 2001, 19 patients, with head and neck cancer, had a CDET, for 3 indications. We studied retrospectively sensitivity (Se) and specificity (Sp) rates for these 3 indications. RESULTS: 1 degree) Detection of unknown primary head and neck cancers with lymph node manifestation: Se = 100%, Sp = 66,7%. 2 degrees) Detection of body metastasis: Se = 50%, Sp = 33%. 3 degrees) Detection of local recurrent cancer: Se = 100%, Sp = 25%. CONCLUSION: CDET seems to be useful in finding unknown primary cancers with lymph node manifestation but is not reliable to look for metastasis and local recurrences. It cannot be used in all indications for PET. If no other tool is available, this investigation can be used, keeping in mind its limitations.

Diagnosis, Differential↗
PubMed1990

[The status of computerized tomography and conventional tomography in the assessment of endobronchial growth and extension of central bronchial cancer].

In comparison with endoscopy, computed tomography can produce excellent results with respect to the endobronchial spread of central bronchial carcinomas. Used for the same purpose, conventional tomography of the central bronchial system is greatly inferior. With respect to an evaluation of the endobronchial tumour growth configuration, computed tomography of the chest showed agreement with the endoscopic findings in only 56 per cent of all cases. This would seem to indicate that for the planning of palliative bronchological measures, such as, for example, laser therapy and afterloading treatment, prior endoscopic inspection is indispensable. By themselves, the results obtained with the imaging procedures described in this article are not adequate.

Bronchi↗
PubMed1988

Positron emission tomography--a new approach to brain chemistry. Council on Scientific Affairs. Report of the Positron Emission Tomography Panel.

Positron emission tomography permits examination of the chemistry of the brain in living human beings. Until recently, positron emission tomography had been considered a research tool, but it is rapidly moving into clinical practice. This report describes the uses and applications of positron emission tomography in examinations of patients with strokes, epilepsy, malignancies, dementias, and schizophrenia and in basic studies of synaptic neurotransmission.

Brain Chemistry↗
PubMed1984

[Value of sonography, computer tomography, hepatobiliary scintigraphy and nuclear magnetic tomography in diseases of the gallbladder and bile ducts].

The effectiveness of ultrasound, computed tomography, hepatobiliary scintigraphy and nuclear magnetic resonance in diseases of the biliary tract is described. Ultrasound should be the first examination in clinical suspicion of cholelithiasis and has a higher accuracy than oral cholecystography. Computed tomography is very expensive and should be carried out in suspected gallbladder carcinoma, cholecystitis with abscess formation, tumour in the porta hepatis and pancreatic head and in sonographically unclear cases. Nuclear magnetic resonance can determine the ability of the gallbladder to concentrate bile. Ultrasound can distinguish with high accuracy between obstructive and inflammatory jaundice. In clinical suspicion of bile duct lesions an infusion cholangiogram must be carried out, if bilirubin is lower than 5 mg%; if bilirubin is higher, an ERC or PTC should be performed. If in biliary obstruction a suspicion of tumour in porta hepatis or head of the pancreas is present, computed tomography should be effected.

Bile Duct Diseases↗
PubMed1984

[Value of intravesical ultrasound tomography and computer tomography in the evaluation of the depth of infiltration of bladder tumors].

In 83% of cases the tumour could be correctly staged by intravesical sonography. Computed tomography gave a correct staging in 80%. By a combination of both methods the depths of tumour infiltration could be established exactly in 90%. Both methods are supplementary since the lower stages are better assessable by intravesical ultrasonic tomography whereas in the advanced stages computer tomography combined with pneumocystography permits a more exact evaluation of the depth of tumour infiltration.

Humans↗
PubMed1998

Assessment of malignancy of glioma by positron emission tomography with 18F-fluorodeoxyglucose and single photon emission computed tomography with thallium-201 chloride.

The histological diagnosis and proliferative potential measured by bromodeoxyuridine (BrdU) labelling index (LI) were correlated with preoperative CT and contrast-enhanced, MRI, 18F-fluorodeoxyglucose positron emission tomography (PET) and 201T1 single photon emission computed tomography (SPECT) in 43 patients with various grades of glioma. 201T1 SPECT had slightly higher sensitivity to tumours with BrdU LI > or = 5% (showing 10/10) than 18F-FDG PET (7/8 tumours). 18F-FDG PET was better for identifying tumours of BrdU LI < 1% (13/15) than 201T1 SPECT (13/22). Accumulation of 201T1 in the tumour was slightly different from contrast enhancement on CT and/or MRI, and gave "false-positive" results in some low-grade gliomas. However, 201T1 SPECT, which is available in many hospitals and may cost less, provided useful information to supplement that from CT and MRI.

Astrocytoma↗
PubMed2004

Feasibility of optimizing the dose distribution in lung tumors using fluorine-18-fluorodeoxyglucose positron emission tomography and single photon emission computed tomography guided dose prescriptions.

The information provided by functional images may be used to guide radiotherapy planning by identifying regions that require higher radiation dose. In this work we investigate the dosimetric feasibility of delivering dose to lung tumors in proportion to the fluorine-18-fluorodeoxyglucose activity distribution from positron emission tomography (FDG-PET). The rationale for delivering dose in proportion to the tumor FDG-PET activity distribution is based on studies showing that FDG uptake is correlated to tumor cell proliferation rate, which is shown to imply that this dose delivery strategy is theoretically capable of providing the same duration of local control at all voxels in tumor. Target dose delivery was constrained by single photon emission computed tomography (SPECT) maps of normal lung perfusion, which restricted irradiation of highly perfused lung and imposed dose-function constraints. Dose-volume constraints were imposed on all other critical structures. All dose-volume/function constraints were considered to be soft, i.e., critical structure doses corresponding to volume/function constraint levels were minimized while satisfying the target prescription, thus permitting critical structure doses to minimally exceed dose constraint levels. An intensity modulation optimization methodology was developed to deliver this radiation, and applied to two lung cancer patients. Dosimetric feasibility was assessed by comparing spatially normalized dose-volume histograms from the nonuniform dose prescription (FDG-PET proportional) to those from a uniform dose prescription with equivalent tumor integral dose. In both patients, the optimization was capable of delivering the nonuniform target prescription with the same ease as the uniform target prescription, despite SPECT restrictions that effectively diverted dose from high to low perfused normal lung. In one patient, both prescriptions incurred similar critical structure dosages, below dose-volume/function limits. However, in the other patient, critical structure dosage from the nonuniform dose prescription exceeded dose-volume/function limits, and greatly exceeded that from the uniform dose prescription. Strict compliance to dose-volume/ function limits would entail reducing dose proportionality to the FDG-PET activity distribution, thereby theoretically reducing the duration of local control. Thus, even though it appears feasible to tailor lung tumor dose to the FDG-PET activity distribution, despite SPECT restrictions, strict adherence to dose-volume/function limits could compromise the effectiveness of functional image guided radiotherapy.

Algorithms↗
PubMed2005

Assessment of three-dimensional X-ray images: reconstruction from conventional tomograms, compact computerized tomography images, and multislice helical computerized tomography images.

Three-dimensional X-ray images (3D images) were used for imaging diagnosis in the oral and maxillofacial region. These images could be fundamentally reconstructed from various tomograms, though clinical 3D images were mainly reconstructed from computerized tomography (CT) images. In this investigation, 3D images were reconstructed from conventional tomograms with a panoramic unit, compact CT images, and multislice helical CT images, and the usefulness of each system was subjectively assessed for dental implant treatment. Three hemilateral dried human mandibles were used and were examined by linear tomography with a panoramic unit, compact CT, and multislice helical CT, and 3D images were reconstructed by using the rendering software for each system. The 3D images were visually evaluated on a 5-point scale covering the alveolar ridge, buccal and lingual bone surface, mental foramen, and tooth sockets. As a result, 3D images reconstructed from conventional tomograms with the panoramic unit were assessed as fair to unsure, compact CT 3D images were assessed as unsure to good, and multislice helical CT 3D images were assessed as good to excellent. It was concluded that compact CT 3D images and multislice helical CT 3D images were useful in dental implant treatment.

Dental Implantation, Endosseous↗
PubMed2006

Staging accuracy in mycosis fungoides and sezary syndrome using integrated positron emission tomography and computed tomography.

OBJECTIVES: To evaluate the usefulness of integrated positron emission tomography and computed tomography (PET/CT) in staging mycosis fungoides (MF) and Sézary syndrome and to correlate PET/CT data with histopathologic diagnosis of lymph nodes (LNs). DESIGN: A single-center, prospective cohort analysis. SETTING: Academic referral center for cutaneous lymphoma. PATIENTS: Thirteen patients with MF and SS at risk for secondary LN involvement. Interventions Patients were clinically evaluated based on general physical examination, total body skin examination, and laboratory screening. They underwent integrated PET/CT followed by excisional biopsy of LNs. MAIN OUTCOME MEASURES: We used PET/CT to assess LN size and metabolic activity. Enlarged LNs were defined as axillary or inguinal LNs with a short axis 1.5 cm or larger; or cervical LN, with a short axis 1.0 cm or larger. We classified LN pathologic results according to National Cancer Institute (LN1-4) and World Health Organization (WHO 1-3) criteria. We quantified PET activity using standardized uptake value (SUV) and correlated with LN grade. RESULTS: Based on CT size criteria alone, only 5 patients had enlarged LNs, whereas PET revealed hypermetabolic LNs in all 13 patients. Six patients had LN1-3, and 7 had effacement of LN architecture by lymphoma cells (LN4). Of the 7 patients with LN4 nodes, 4 had SS, and 3 had tumorous MF. Two patients with LN4 nodes had inguinal LNs smaller than 1.5 cm and would have been assigned an N0 classification without the use of integrated PET/CT. Correlation of SUV with LN grade revealed that LN1-3 nodes were associated with a mean SUV of 2.7 (median SUV, 2.2; range, 2.0-4.7) and LN4 nodes were associated with a mean SUV of 5.4 (median SUV, 3.9; range, 2.1-11.8). Patients with large cell transformation had the highest SUVs. CONCLUSIONS: For staging MF and SS, PET/CT was more sensitive in detecting LN involved by lymphoma compared with CT data alone and thus may provide more accurate staging and prognostic information. The intensity of PET activity correlated with histologic LN grade.

Adult↗
PubMed2001

Occult primary tumors of the head and neck: accuracy of thallium 201 single-photon emission computed tomography and computed tomography and/or magnetic resonance imaging.

OBJECTIVE: To determine the accuracy of thallium 201 single-photon emission computed tomography (thallium SPECT) and computed tomography and/or magnetic resonance imaging (CT/MRI) in the detection of occult primary tumors of the head and neck. DESIGN: Study of diagnostic tests. SETTING: National Cancer Institute, Amsterdam, the Netherlands. PATIENTS AND METHODS: Thirty-two patients with a neck node metastasis of an epithelial tumor and negative findings by mirror examination at initial presentation were included in the study. Twenty-nine patients underwent thallium SPECT and CT/MRI before examination under general anesthesia (EUA). In 3 patients only thallium SPECT was performed before EUA. Histological confirmation of an occult primary tumor during EUA was used as the gold standard. Negative radiodiagnostic and nuclear findings in the upper aerodigestive tract in the presence of a primary carcinoma other than of the head and neck were interpreted as true-negative findings. RESULTS: For thallium SPECT the following results were recorded: sensitivity, 67%; specificity, 69%; accuracy, 69%; positive predictive value, 33%; and negative predictive value, 90%. In 1 patient, thallium whole body scan indicated a primary carcinoma beyond the mucosal lining of the upper aerodigestive tract. The CT/MRI results were as follows: sensitivity, 71%; specificity, 73%; accuracy, 72%; positive predictive value, 45%; and negative predictive value, 89%. CONCLUSIONS: Thallium SPECT and CT/MRI showed comparable results for detection of occult primary tumors of the head and neck. A potential advantage of thallium SPECT is that it allows total body screening.

Adult↗
PubMed2006

The role of positron emission tomography and computed tomography fusion in the management of early-stage and advanced-stage primary head and neck squamous cell carcinoma.

OBJECTIVE: To evaluate the role of positron emission tomography and computed tomography (PET-CT) fusion in the management of early-stage and advanced-stage primary head and neck squamous cell cancer. DESIGN: Retrospective analysis, with a blinded evaluation of clinical data and formation of a treatment plan. SETTING: Single tertiary academic medical institution. Patients Thirty-six patients with previously untreated head and neck squamous cell carcinoma who underwent staging CT or magnetic resonance imaging of the neck prior to undergoing PET-CT as part of their initial diagnostic evaluation between July 2000 and January 2005. MAIN OUTCOME MEASURES: Confirmation or alteration of the treatment plan with the addition of the PET-CT information compared with traditional clinical and radiological data alone for early-stage and advanced-stage disease. When available, histopathological results were correlated with the PET-CT findings. RESULTS: Among the 36 patients, PET-CT provided additional information that confirmed the treatment plan in 25 patients (69%) and altered the treatment plan in 11 patients (31%). Six of 11 patients in the altered-treatment group had their tumors upstaged. Four of 8 patients with early-stage tumors had their treatment plan altered, compared with 7 of 28 patients with advanced-stage disease. Among 18 patients who underwent a surgical intervention for their primary tumor, PET-CT identified the primary tumor in all 18 patients and, based on histopathological findings, correctly staged the regional nodal disease in 9 of 16 patients who had their nodal disease addressed. CONCLUSION: The use of PET-CT is important in the initial treatment planning of early-stage and advanced-stage head and neck squamous cell carcinoma.

Adolescent↗
PubMed1995

A technique utilizing positron emission tomography and magnetic resonance/computed tomography image fusion to aid in surgical navigation and tumor volume determination.

Brain tumors are histologically heterogeneous. A technique for three-dimensional fusing of computed tomography (CT) or magnetic resonance images (MRI) with positron emission tomography (PET) images is described. This allows the anatomic detail provided by CT or MRI scans to be combined with the information about metabolic activity provided by PET scans. The fused images allowed selection of the most metabolically active portions of tumors. Fusion of CT and MRI images with PET scans has allowed first-pass diagnostic yield by providing the surgeon with a map of anatomical as well as functional (metabolic) detail. We describe a technique to allow routine fusion of MRI, CT, and PET information to help guide the neurosurgeon.

Adult↗
PubMed1991

Single photon emission computed tomography and positron emission tomography in cancer imaging.

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are now being used to improve the information available from radioisotopic imaging of patients with cancer. These nuclear medicine techniques offer the potential for studying regional function and biochemistry by using radiolabeled substrates. The chemical changes of malignancy precede anatomic changes, and PET and/or SPECT may detect these changes before anatomic changes have occurred. The superiority of SPECT compared with planar imaging has been demonstrated for cardiac and brain imaging. Radiopharmaceuticals containing technetium 99 m (99mTc) are best suited for SPECT imaging because large amounts of radioactivity are administered and the collimator-camera systems are optimized for the 140 keV photons of 99mTc. The current interest in imaging cancer with SPECT relates to the use of gallium 67 citrate and monoclonal antibodies labeled with iodine 123 or indium 111. SPECT can image these radioisotopes, but the advantages compared with planar imaging have not been clearly defined. Furthermore, the ability to quantitate the distribution of single photon emitters other than 99mTc has not been demonstrated. New SPECT systems with three heads or rings of detectors offer promise for improved, quantitative imaging. PET has the capability of imaging tracers with the biologically important elements C-11, N-13, O-15, and F-18 used for positron labeling. These radioisotopes have short half-lives and require a cyclotron close to the PET facility. The most prominently used radiopharmaceutical for PET is F-18 fluorodeoxyglucose (FDG). PET studies with FDG in patients with primary brain tumors have demonstrated the ability to determine the degree of malignancy, to differentiate necrosis from recurrent tumor after radiation therapy or chemotherapy, and to predict prognosis. Other metabolic functions of cancer have been studied, including amino acid accumulation, thymidine uptake, oxygen utilization, intermediary metabolism, and receptor status. PET has the potential to make a major impact on the characterization of a malignancy and the effect of therapy.

Fluorine Radioisotopes↗