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Biomedical subjects

Homer A Macapinlac

Publications and source records attributed to Homer A Macapinlac.

At least 19 recordsLinked to original sources
PubMed2007

Detection of interval distant metastases: clinical utility of integrated CT-PET imaging in patients with esophageal carcinoma after neoadjuvant therapy.

BACKGROUND: The objective of the study was to determine the utility of integrated computed tomography / positron emission tomography (CT-PET) imaging for detecting interval distant metastases and assessing therapeutic response in patients with locally advanced, potentially resectable esophageal carcinoma after neoadjuvant therapy. METHODS: A retrospective study was performed of 88 patients with potentially resectable esophageal carcinoma who received neoadjuvant therapy before planned surgical resection. CT-PET before and after completion of neoadjuvant was used for evaluating therapeutic response; response criteria were based on qualitative and semiquantitative analyses. RESULTS: Neoadjuvant therapy comprised chemoradiotherapy in 85 patients, with prior induction chemotherapy in 39 patients. Fifty-five patients proceeded to esophagectomy. Repeat CT-PET was performed after induction chemotherapy (n = 23) and after completing chemoradiotherapy (n = 85). CT-PET identified the interval appearance of metastatic disease in 7 (8%) patients. For assessment of locoregional therapeutic response, CT-PET was unable to predict pathological response to neoadjuvant therapy in the primary tumor or locoregional lymph nodes. CT-PET had sensitivity, specificity, and positive and negative predictive values of 57%, 46%, 39%, and 64%, respectively, for detection of residual macroscopic malignancy within the primary tumor; and sensitivity, specificity, and positive and negative predictive values of 0%, 90%, 0%, and 69% for detection of residual malignancy within resected lymph nodes. CONCLUSIONS: CT-PET performed after neoadjuvant therapy in patients with potentially resectable esophageal carcinoma is important for detecting interval metastases that preclude surgical resection, but is of limited utility for assessing locoregional therapeutic response.

Adenocarcinoma↗
PubMed2006

Positron emission tomography of the brain.

Positron emission tomography (PTE) is a technique that allows imaging of the temporal and spatial distribution of positron-emitting radionuclides. The purpose of this article is to outline the current clinical use for PET imaging in the brain and other radiopharmaceutical used for assessing various physiologic parameters pertaining to tumor metabolism.

Brain↗
PubMed2006

PET/CT imaging techniques, considerations, and artifacts.

In the past few years, positron emission tomography/computed tomography (PET/CT) imaging has increasingly been used for the diagnosis, staging, and restaging of malignant diseases. The success of this emerging modality has primarily been due to its ability to combine the advantages of both PET and CT imaging while minimizing their separate weaknesses. The aim of this paper is to provide an overview of the basis behind PET/CT imaging, its advantages, and discuss its imaging artifacts with special emphasis on proposed correction techniques. A brief discussion regarding the use of PET/CT imaging for radiation treatment planning is also presented.

Artifacts↗
PubMed2006

Esophageal cancer: the role of integrated CT-PET in initial staging and response assessment after preoperative therapy.

Esophageal cancer, an uncommon neoplasm, has been increasing in incidence over the past few decades. Optimal management of patients is determined by the stage of disease at presentation, patient performance status, and location of the primary cancer. Recently, there has been increasing use of multimodality therapy in suitable candidates that employs preoperative chemotherapy and/or radiation followed by surgical resection. This evolving treatment strategy together with the substantial morbidity and mortality associated with esophagectomy makes appropriate patient selection critical. Computed tomography (CT) and endoscopy/endoscopic ultrasonography are usually carried out to initially stage patients with esophageal cancer, to determine primary tumor response, and to detect nodal and distant metastases after preoperative therapy. Positron emission tomography (PET) with [18F]-fluoro-2-deoxy-D-glucose and integrated CT-PET are useful in the initial staging of patients with esophageal cancer and in the prediction of pathologic response, disease-free interval, and overall survival after preoperative therapy. Importantly, integrated CT-PET imaging decreases the number of futile attempts at surgical resection, mainly because of the detection of occult distant metastases. The following sections review the use of integrated CT-PET imaging in determining the T, N, and M descriptors of the American Joint Commission on Cancer's 2002 guidelines for pathologic and clinical staging at initial diagnosis and after chemoradiation therapy in those patients being considered for surgical resection.

Algorithms↗
PubMed2006

Interobserver and intraobserver variability of standardized uptake value measurements in non-small-cell lung cancer.

OBJECTIVES: To assess interobserver and intraobserver variabilities in measuring the maximal standardized uptake value (SUV) of non-small-cell lung cancer. METHODS: Positron emission tomography-computed tomography examinations of 20 consecutive patients referred for initial evaluation of newly diagnosed non-small-cell lung cancer were retrospectively reviewed by 5 experienced positron emission tomography-computed tomography readers, who independently measured the maximal SUV/body weight of the primary tumors. Interobserver and intraobserver variabilities were assessed by using 4 statistical methods: correlation, regression analysis, Bland-Altman analysis, and analysis of variance. The SUV measurements derived in the study were compared with the SUV measurements documented in the original reports using correlation and regression analysis. The percentages of tumors whose retrospective SUV measurements were more than 20% different and more than 25% different from those in the original report were assessed. RESULTS: Both interobserver and intraobserver SUV measurements were highly reproducible. Pearson correlation coefficients were greater than 0.95 and 0.94, respectively. Good interobserver and intraobserver agreement was shown with regression analysis (F test P value >0.05), the Bland-Altman analysis, and analysis of variance (F test P value >0.95). The mean original SUV was much less than the mean study SUV (P<0.05). The study SUV differed from the SUV of the original report by more than 20% in 50% of the tumors, and by more than 25% in 45% of the tumors. CONCLUSIONS: There was excellent interobserver and intraobserver agreement in SUVs measured in the study environment but poor agreement between study SUVs and those documented in original reports, which can affect treatment decisions substantially.

Aged↗
PubMed2006

Quantifying the effect of IV contrast media on integrated PET/CT: clinical evaluation.

OBJECTIVES: The use of IV contrast media in PET/CT can result in an overestimation of PET attenuation factors that potentially can affect interpretation. The objective of this study was to quantify the effect of IV contrast media in PET/CT and assess its impact on patients with intrathoracic malignancies. MATERIALS AND METHODS: Nine patients had CTs performed with and without IV contrast media followed by (18)F-FDG PET. PET images were reconstructed using contrast-enhanced and unenhanced CT. To quantify the effect of contrast media on standardized uptake values (SUV), similar regions of interest (ROIs) were drawn on the subclavian vein, heart, liver, spleen, and site of malignancy on both CT and corresponding reconstructed PET images, and the mean and maximum values were compared. In addition, two physicians blinded to the imaging parameters that were used evaluated the reconstructed PET images to assess whether IV contrast media had an effect on clinical interpretation. RESULTS: For all patient studies, the subclavian vein region on the ipsilateral side of contrast media administration had the highest increase in CT numbers with a corresponding average SUV(max) increase of 27.1%. Similarly, ROIs of the heart and at the site of malignancy showed an increase in the maximum attenuation value with a corresponding average SUV(max) increase of 16.7% and 8.4%, respectively. Other locations had relatively small attenuation value differences with a correspondingly negligible SUV variation. CONCLUSION: Although there is a significant increase in SUV in regions of high-contrast concentration when contrast-enhanced CT is used for attenuation correction, this increase is clinically insignificant. Accordingly, in PET/CT, IV contrast-enhanced CT can be used in combination with the PET to evaluate patients with cancer.

Contrast Media↗
PubMed2006

Truncation artifact on PET/CT: impact on measurements of activity concentration and assessment of a correction algorithm.

OBJECTIVE: Discrepancy between fields of view (FOVs) in a PET/CT scanner causes a truncation artifact when imaging extends beyond the CT FOV. The purposes of this study were to evaluate the impact of this artifact on measurements of 18F-FDG activity concentrations and to assess a truncation correction algorithm. MATERIALS AND METHODS: Two phantoms and five patients were used in this study. In the first phantom, three inserts (water, air, bone equivalent) were placed in a water-filled cylinder containing 18F-FDG. In the second phantom study, a chest phantom and a 2-L bottle fitted with a bone insert were used to simulate a patient's torso and arm. Both phantoms were imaged while positioned centrally (baseline) and at the edge of the CT FOV to induce truncation. PET images were reconstructed using attenuation maps from truncated and truncation-corrected CT images. Regions of interest (ROIs) drawn on the inserts, simulated arm, and background water of the baseline truncated and truncation-corrected PET images were compared. In addition, extremity malignancies of five patients truncated on CT images were reconstructed with and without correction and the maximum standard uptake values (SUVs) of the malignancies were compared. RESULTS: Truncation artifact manifests as a rim of high activity concentration at the edge of the truncated CT image with an adjacent low-concentration region peripherally. The correction algorithm minimizes these effects. Phantom studies showed a maximum variation of -5.4% in the truncation-corrected background water image compared with the baseline image. Activity concentration in the water insert was 6.3% higher while that of air and bone inserts was similar to baseline. Extremity malignancies showed a consistent increase in the maximum SUV after truncation correction. CONCLUSION: Truncation affects measurements of 18F-FDG activity concentrations in PET/CT. A truncation-correction algorithm corrects truncation artifacts with small residual error.

Adult↗
PubMed2006

Incidental findings on integrated PET/CT that do not accumulate 18F-FDG.

OBJECTIVE: The purpose of this study was to report the prevalence of abnormalities that do not show increased 18F-FDG uptake on the CT component of integrated PET/CT in patients with non-small cell lung cancer. MATERIALS AND METHODS: Images from all PET/CT studies performed consecutively between April and October 2003 on patients with non-small cell lung cancer were retrospectively reviewed. All abnormalities present on the CT component of the PET/CT scans that did not show abnormally increased 18F-FDG uptake were documented. RESULTS: Three hundred twenty-one patients with non-small cell lung cancer (179 men, 142 women; mean age, 67 years; age range, 38-91 years) underwent initial staging (198/321 [62%]) or restaging (123/321 [38%]) PET/CT imaging during the study period. In 263 (82%) of the patients, CT showed 1,231 abnormalities that were not 18F-FDG avid. The abnormalities were located in the thorax (n = 650), abdomen and pelvis (n = 444), head and neck (n = 69), and bony skeleton (n = 68). In total, 298 (24%) of the abnormalities that were not 18F-FDG avid were located outside the range of a standard thoracic CT scan. The clinical importance of these abnormalities was classified as major (n = 48 [4%]), moderate (n = 465 [38%]), or minor (n = 718 [58%]). Four (1%) of the patients had findings of major clinical importance that did not show increased 18F-FDG uptake and were previously unsuspected. CONCLUSION: Among patients with non-small cell lung cancer undergoing PET/CT, there is a high prevalence of CT abnormalities that do not show correlative 18F-FDG avidity but that may be clinically important.

Adult↗
PubMed2005

Lymphomatous involvement of gastrointestinal tract: evaluation by positron emission tomography with (18)F-fluorodeoxyglucose.

AIM: To demonstrate the (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) findings in patients with non-Hodgkinos lymphoma (NHL) involving the gastrointestinal (GI) tract and the clinical utility of modality despite of the known normal uptake of FDG in the GI tract. METHODS: Thirty-three patients with biopsy-proven gastrointestinal NHL who had undergone FDG-PET scan were included. All the patients were injected with 10-15 mCi FDG and scanned approximately 60 min later with a CTI/Siemens HR (+) PET scanner. PET scans were reviewed and the maximum standard uptake value (SUV(max)) of the lesions was measured before and after the treatment, if data were available and compared with histologic diagnoses. RESULTS: Twenty-five patients had a high-grade lymphoma and eight had a low-grade lymphoma. The stomach was the most common site of the involvement (20 patients). In high-grade lymphoma, PET showed focal nodular or diffuse hypermetabolic activity. The average SUV(max)+/-SD was 11.58+/-5.83. After the therapy, the patients whose biopsies showed no evidence of lymphoma had a lower uptake without focal lesions. The SUV(max)+/-SD decreased from 11.58+/-5.83 to 2.21+/-0.78. In patients whose post-treatment biopsies showed lymphoma, the SUV(max)+/-SD was 9.42+/-6.27. Low-grade follicular lymphomas of the colon and stomach showed diffuse hypermetabolic activity in the bowel wall (SUV(max) 8.2 and 10.3, respectively). The SUV(max) was 2.02-3.8 (mean 3.02) in the stomach lesions of patients with MALT lymphoma. ONCLUSION: (18)F-FDG PET contributes to the diagnosis of high-grade gastrointestinal non-Hodgkin's lymphoma, even when there is the normal background FDG activity. Furthermore, the SUV plays a role in evaluating treatment response. Low-grade NHL demonstrates FDG uptake but at a lesser intensity than seen in high-grade NHL.

Adult↗
PubMed2005

Effect of colony-stimulating factor and conventional- or high-dose chemotherapy on FDG uptake in bone marrow.

PURPOSE: Granulocyte or granulocyte-macrophage colony stimulating factor (CSF), usually used in conjunction with chemotherapy, may interfere with the( 18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) reading. The purpose of this study is to evaluate the effects of CSF, conventional-or high-dose chemotherapy on bone marrow FDG uptake. METHODS: Two hundred and forty-one FDG PET scans obtained in 163 patients with lymphoma and no pathologically and radiologically proven bone marrow involvement were analyzed. The standardized uptake value (SUV) of each patient's spine was measured. RESULTS: Among patients with no recent history of CSF use, the average SUV in 36 patients with no history of chemotherapy was 1.60+/-0.34, that in 49 patients with a history of conventional-dose chemotherapy was 1.37+/-0.32, and that in 12 patients with a history of high-dose chemotherapy was 1.26+/-0.25 (P=0.008 and 0.002, respectively by Mann-Whitney U test). In 80 patients treated with conventional-dose chemotherapy and CSF, the average SUV after discontinuation of CSF was as follows: 0-7 days, 2.37+/-1.19; 8-14 days: 2.04+/-0.67; 15-21 days: 1.87+/-0.52; 22-30 days: 1.59+/-0.18; 31-90 days: 1.54+/-0.36. In 45 patients treated with high-dose chemotherapy and CSF, no significant increase in bone marrow uptake was seen in most of them. CONCLUSION: Bone marrow FDG uptake may be increased by CSF treatment and may be decreased by chemotherapy. In patients treated with conventional-dose chemotherapy and CSF, increased marrow uptake will return to the pretreatment value approximately 1 month after discontinuation of CSF.

Adult↗
PubMed2005

Imatinib resistance in gastrointestinal stromal tumors.

Conventional chemotherapeutic drugs are ineffective in treatment of gastrointestinal stromal tumors (GISTs). Imatinib (STI571, Gleevec, Glivec; Novartis Pharmaceuticals, East Hanover, NJ), a selective inhibitor of KIT, ABL, BCR-ABL, PDGFRA, and PDGFRB, represents a new paradigm of targeted cancer therapy and has revolutionized the treatment of patients with chronic myelogenous leukemia and GISTs. Unfortunately, imatinib resistance has emerged. The reported mechanism of imatinib resistance in GISTs involves missense mutation in the kinase domain of KIT, including Thr670Ile, Tyr823Asp, and Val654Ala. The established mechanisms and potential mechanisms of imatinib resistance in GISTs, the imaging studies indicative of early development of imatinib resistance, and the management of imatinib-resistant GISTs are discussed.

Antineoplastic Agents↗
PubMed2005

Integrated computed tomography-positron emission tomography in patients with potentially resectable malignant pleural mesothelioma: Staging implications.

BACKGROUND: Integrated computed tomography-positron emission tomography imaging with coregistration of anatomic and functional imaging data may improve the accuracy of malignant pleural mesothelioma staging. We evaluate the use of integrated computed tomography-positron emission tomography in patients with malignant pleural mesothelioma who are being considered for extrapleural pneumonectomy. METHODS: Twenty-nine patients with malignant pleural mesothelioma who were judged to be candidates for extrapleural pneumonectomy after clinical and conventional radiologic evaluation underwent whole-body integrated computed tomography-positron emission tomography and pathologic staging. Two reviewers blinded to the results of clinical and pathologic staging retrospectively evaluated computed tomography, positron emission tomography, and coregistered computed tomography-positron emission tomography images. Staging was performed according to the International Mesothelioma Interest Group TNM staging system. Histopathology and/or results of further radiologic evaluation or follow-up served as the reference standard. RESULTS: Integrated computed tomography-positron emission tomography provided additional information in 11 of 29 patients that precluded extrapleural pneumonectomy. The overall tumor stage was correctly classified in 21 of 29 patients. The tumor stage was correctly determined in 15 of 24 patients, 6 of whom had T4 (nonresectable) disease. The node stage was accurately determined in 6 of 17 patients. Extrathoracic metastases not identified by routine clinical and conventional radiologic evaluation were detected in 7 of 29 patients and were found to be diffuse (n = 2) or solitary (n = 5). CONCLUSIONS: Integrated computed tomography-positron emission tomography increases the accuracy of malignant pleural mesothelioma staging and is important in determining the appropriate therapy in patients being considered for extrapleural pneumonectomy.

Adult↗
PubMed2005

Technology insight: PET and PET/CT in head and neck tumor staging and radiation therapy planning.

The evolving utilization of functional imaging, mainly 2-[18F]fluoro-2-deoxyglucose (18FDG) imaging, with positron emission tomography (PET) and PET/CT, is profoundly altering head and neck tumor staging approaches, radiation treatment planning, and follow-up management. Tumor-node-metastasis staging with PET/CT has improved the characterization of patient disease versus CT, MRI, or PET alone, thereby affecting patient disease management. Therefore, the utilization of PET/CT is appropriate for head and neck cancer staging in the initial presentation and in the recurrent setting. In the setting of radiation therapy treatment planning, PET-directed tumor volume contouring is not ready for clinical practice without further technological improvements in imaging specificity/sensitivity and resolution. Patient or organ motion might interfere with the accuracy of anatomical co-alignment, and variability in defining the threshold of imaging signals on PET images can affect the contour of the biological tumor volume. The use of PET/CT for staging and detecting both primary and recurrent head and neck cancer is valuable; however, its application in radiation treatment planning should be viewed as investigational.

Female↗
PubMed2005

Focal uptake of fluorodeoxyglucose by the thyroid in patients undergoing initial disease staging with combined PET/CT for non-small cell lung cancer.

PURPOSE: To retrospectively evaluate the prevalence of focal fluorodeoxyglucose (FDG) uptake by the thyroid gland on combined positron emission tomographic (PET) and computed tomographic (CT) scans in patients undergoing staging of newly diagnosed non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and the study was Health Insurance Portability and Accountability Act-compliant. Whole-body PET/CT scans and medical records of 140 consecutive patients with newly diagnosed NSCLC (80 men, 60 women; mean age, 66 years; range, 39-89 years) were retrospectively reviewed by two experienced PET/CT scan readers. Maximum standardized uptake value (SUV) was calculated for FDG-avid thyroid foci. Corresponding thyroid CT findings were recorded in patients with focal increased FDG thyroid uptake. RESULTS: PET results showed that six patients (4.3%) had seven foci of increased FDG uptake in the thyroid. Five of the seven foci (in four patients) corresponded to a low-attenuation thyroid lesion on the non-enhanced CT scan. Lesions ranged in diameter from 0.8 to 2.5 cm. Four of the lesions were found to be papillary thyroid cancers at fine-needle aspiration biopsy. The fifth lesion was found to be benign at thyroidectomy. The remaining two patients did not have histologic confirmation of their thyroid lesion because no specific biopsy site was visualized on CT or sonographic images and lesions were considered benign. Maximum SUV of the thyroid cancers ranged from 3.0 to 32.9 (mean, 13.7). Maximum SUV of benign thyroid lesions ranged from 4.6 to 6.2 (mean, 5.4). CONCLUSION: Focal thyroid FDG uptake found during the initial staging of NSCLC at PET/CT indicates a high likelihood of primary thyroid cancer.

Adult↗
PubMed2005

FDG-PET in head and neck, and thyroid cancer.

FDG-PET has become a standard clinical imaging modality in patients with head and neck cancer. It contributes valuable information in localizing a primary tumor in patients with neck nodal metastases from an unknown primary, in the staging of primary head and neck cancer, and in the detection of recurrent disease. In addition, FDG-PET provides independent prognostic information in patients with newly diagnosed and recurrent head and neck cancer. PET-CT improves lesion localization and accuracy of FDG-PET and is strongly recommended in patients with head and neck cancer. After thyroidectomy, FDG-PET has proven useful in patients with clinical or serological evidence of recurrent or metastatic thyroid carcinoma but negative whole body iodine scan. PET shows metastatic disease in up to 90% of these patients, thereby providing a rational basis for further studies and therapy. In patients with medullary thyroid cancer with elevated calcitonin levels following thyroidectomy, FDG-PET has a sensitivity of 70-75% for localizing metastatic disease. Occasionally incidental intense FDG uptake is observed in the thyroid gland on whole-body PET studies performed for other indications. Although diffuse FDG uptake usually indicates thyroiditis, focal uptake has been related to thyroid cancer in 25-50% of cases and should therefore be evaluated further if a proven malignancy would cause a change in patient management.

Fluorodeoxyglucose F18↗
PubMed2004

A missense mutation in KIT kinase domain 1 correlates with imatinib resistance in gastrointestinal stromal tumors.

KIT gain of function mutations play an important role in the pathogenesis of gastrointestinal stromal tumors (GISTs). Imatinib is a selective tyrosine kinase inhibitor of ABL, platelet-derived growth factor receptor (PDGFR), and KIT and represents a new paradigm of targeted therapy against GISTs. Here we report for the first time that, after imatinib treatment, an additional specific and novel KIT mutation occurs in GISTs as they develop resistance to the drug. We studied 12 GIST patients with initial near-complete response to imatinib. Seven harbored mutations in KIT exon 11, and 5 harbored mutations in exon 9. Within 31 months, six imatinib-resistant rapidly progressive peritoneal implants (metastatic foci) developed in five patients. Quiescent residual GISTs persisted in seven patients. All six rapidly progressive imatinib-resistant implants from five patients show an identical novel KIT missense mutation, 1982T-->C, that resulted in Val654Ala in KIT tyrosine kinase domain 1. This novel mutation has never been reported before, is not present in pre-imatinib or post-imatinib residual quiescent GISTs, and is strongly correlated with imatinib resistance. Allelic-specific sequencing data show that this new mutation occurs in the allele that harbors original activation mutation of KIT.

Alleles↗