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Seza A Gulec

Publications and source records attributed to Seza A Gulec.

14 recordsLinked to original sources
PubMed2006

PET-Probe: Evaluation of Technical Performance and Clinical Utility of a Handheld High-Energy Gamma Probe in Oncologic Surgery.

BACKGROUND: Positron emission tomography (PET) has become an invaluable part of patient evaluation in surgical oncology. PET is less than optimal for detecting lesions <1 cm, and the intraoperative localization of small PET-positive lesions can be challenging as a result of difficulties in surgical exposure. We undertook this investigation to assess the utility of a handheld high-energy gamma probe (PET-Probe) for intraoperative identification of 18F-deoxyglucose (FDG)-avid tumors. METHODS: Forty patients underwent a diagnostic whole-body FDG-PET scan for consideration for surgical exploration and resection. Before surgery, all patients received an intravenous injection of 7 to 10 mCi of FDG. At surgery, the PET-Probe was used to determine absolute counts per second at the known tumor site(s) demonstrated by whole-body PET and at adjacent normal tissue (at least 4 cm away from tumor-bearing sites). Tumor-to-background ratios were calculated. RESULTS: Thirty-two patients (80%) underwent PET-Probe-guided surgery with therapeutic intent in a recurrent or metastatic disease setting. Eight patients underwent surgery for diagnostic exploration. Anatomical locations of the PET-identified lesions were neck and supraclavicular (n = 8), axilla (n = 5), groin and deep iliac (n = 4), trunk and extremity soft tissue (n = 3), abdominal and retroperitoneal (n = 19), and lung (n = 2). PET-Probe detected all PET-positive lesions. The PET-Probe was instrumental in localization of lesions in 15 patients that were not immediately apparent by surgical exploration. CONCLUSIONS: The PET-Probe identified all lesions demonstrated by PET scanning and, in selected cases, was useful in localizing FDG-avid disease not seen with conventional PET scanning.

Adolescent↗
PubMed2004

Gamma-guided diagnostic peritoneal lavage for detection of bowel perforation.

HYPOTHESIS: Bowel perforation can be diagnosed by detection of orally administered technetium Tc 99m sulfur colloid ((99m)Tc SC) in diagnostic peritoneal lavage (DPL) fluid using a handheld gamma-detection probe. DESIGN: A canine intestinal-injury model was used to test the hypothesis. The (99m)Tc SC (55.5 MBq) was administered in 500 mL of saline via a nasogastric tube. A DPL with 500 mL of saline was performed at 60, 90, and 120 minutes after administration of (99m)Tc SC. The radioactivity in the DPL effluent was measured using a handheld gamma probe. A DPL effluent count that was 3 SDs above the background count was considered a positive test result. Twenty animals with perforation and 5 without perforation (negative control) were studied. RESULTS: There were no false-positive gamma-DPL test results. Sensitivity improved by time up to 90 minutes. The lowest positive count in the DPL effluent measured by the gamma probe corresponded to 0.2% of the administered activity. No radioactivity was detected in blood and urine samples or liver and spleen specimens. The sensitivity, specificity, accuracy, positive predictive values, and negative predictive values at 90 minutes were 95%, 100%, 96%, 100%, and 83%, respectively. CONCLUSIONS: gamma-Guided DPL is a highly sensitive and 100% specific test in the detection of small-bowel perforation. Clinical studies are warranted to determine the patient-specific factors affecting diagnostic accuracy.

Animals↗
PubMed2004

Clinicopathologic and radiopharmacokinetic factors affecting gamma probe-guided parathyroidectomy.

HYPOTHESIS: The kinetics of technetium Tc 99m sestamibi (MIBI) in primary hyperparathyroidism are variable and affected by the cellular size of the abnormal glands, the parathyroid hormone levels, and the functional expression of P-glycoprotein (Pgp). The success of gamma probe-guided parathyroidectomy is closely related to the parathyroid-to-thyroid activity ratio at the time of surgery. Preoperative determination of maximum uptake ratio may improve the surgical outcome. DESIGN: Thirty-one patients with primary hyperparathyroidism attributed to a solitary parathyroid adenoma (27 patients) or multiglandular hyperplasia (4 patients) underwent dynamic MIBI imaging preoperatively. Maximum MIBI activity and activity elimination half-life in the abnormal parathyroid glands and thyroid glands were measured, and the maximum uptake ratio was calculated. After a second MIBI injection on the day of surgery, all patients underwent gamma probe-guided parathyroidectomy and cervical exploration. Timing of surgery after MIBI injection was individualized according to the optimal time to surgery (time to maximum uptake ratio), which was determined by preoperative scintigraphy. During surgery, the gamma probe was used to measure ex vivo counts of excised lesions and adjacent postexcision normal tissue (background). Image characteristics, MIBI kinetics, and gamma probe findings were correlated with gland volume, oxyphil cell content, Pgp expression, and serum parathyroid hormone levels. RESULTS: Probe localization of abnormal glands at maximum uptake ratio was successful in all patients. The volume of the parathyroid lesion ranged from 0.03 to 9.8 mL (median, 0.7 mL). Parathyroid maximum MIBI activity correlated with the volume of the gland (r = 0.54, P = .002) and serum parathyroid hormone level (r = 0.58, P = .001). No correlation between maximum MIBI activity and oxyphil cell content or Pgp expression could be demonstrated. Elimination half-life of MIBI from parathyroid inversely correlated with Pgp (r = -0.36, P = .05). The ex vivo lesion-background count ratio positively correlated with volume of the gland (r = 0.66, P = .001) and parathyroid hormone level (r = 0.48, P = .006). Ex vivo lesion counts and Pgp expression were negatively correlated (r = -0.37, P = .04). CONCLUSIONS: A strong relationship between volume of the parathyroid gland, serum parathyroid hormone levels, and MIBI uptake exists in primary hyperparathyroidism. Gamma probe-guided localization of abnormal gland(s) can be more successful if surgery is undertaken at maximum uptake ratio. High Pgp expression increases MIBI parathyroid clearance rate, decreases gamma probe counts, and may significantly alter the optimal time to surgery.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

A new in vitro assay for human tumor angiogenesis: three-dimensional human tumor angiogenesis assay.

BACKGROUND: A human tissue-based angiogenesis assay is needed to study the biology of angiogenesis in human tumor tissue and to tailor drug selection for patients. METHODS: Fragments of tumor tissue are embedded in fibrin gels containing medium 199, endothelial growth medium, fetal bovine serum, and epsilon-aminocaproic acid. Tumor implants sprout angiogenic vessels that progressively grow into the fibrin matrix. The differential growth pattern of tumor cells and angiogenic vessels in the fibrin gel matrix separates the angiogenic vessels and the tumor stroma into independently observable regions (vessel and tumor compartments). The reproducibility of the assay was tested by using fresh tissue obtained from human tumor xenografts (IMR-32 [neuroblastoma], MDA-MB-231 [breast cancer], and LNCaP [prostate cancer]) grown in nude mice and from fresh surgical breast and thyroid cancer specimens. RESULTS: All tumor fragments studied showed angiogenic sprouting into the fibrin matrix. This created an angiogenic vessel compartment, which was separate from the tumor fragment. The capillary nature of sprouting was confirmed histologically by factor VIII immunohistochemistry. The angiogenic growth fraction was >80% in all groups studied. CONCLUSIONS: This assay may allow functional assessment of the angiogenic potential of human tumors and simultaneous evaluation of a therapeutic agent's antitumor and antiangiogenic effects by virtue of its dual-compartmental structure.

Angiogenesis Inhibitors↗
PubMed2003

The role of fluorine-18 deoxyglucose positron emission tomography in the management of patients with metastatic melanoma: impact on surgical decision making.

Malignant melanoma can metastasize to almost any organ site. Optimal management requires sensitive radiographic evaluation of the entire body. The optimal management of patients with metastatic melanoma requires accurate assessment of extent of disease (EOD). The objective of this study was to evaluate the accuracy of fluorine-18 deoxyglucose (FDG) whole-body positron emission tomography (PET) in determination of EOD in patients with metastatic melanoma and its impact on surgical and medical management decisions. Forty-nine patients (30 men, 19 women; aged 25-83 years) with known or suspected metastatic melanoma underwent EOD evaluation using computerized tomography (CT) of the chest, abdomen, and pelvis, and magnetic resonance imaging (MRI) of the brain. After formulation of an initial treatment plan, the patients underwent FDG-PET imaging. The EOD determined by PET was compared with physical examination and conventional radiography findings. Fifty-one lesions were pathologically evaluated. The impact of PET on patient management was assessed based on the alterations made in the initial treatment plan after reevaluation of the patients using the information obtained by PET. The PET scan identified more metastatic sites in 27 of 49 (55%) of the patients who had undergone a complete set of imaging studies, including CT scans of the chest, abdomen, and pelvis, and MRI of the brain. In 6 of those 27 patients, PET detected disease outside the fields of CT and MRI. Fifty-one lesions were resected surgically. Of these, 44 were pathologically confirmed to be melanoma. All lesions larger than 1 cm (29 of 29) were positive on PET, whereas only 2 of 15 (13%) lesions smaller than 1 cm were detected by PET. The results of PET led treatment changes in 24 patients (49%). Eighteen of these changes (75%) were surgical. In 12 cases (67%), the planned operative procedure was cancelled, and in 6 cases (33%), an additional operation(s) was performed. In 6 of 24 (25%) patients, biochemotherapy, radiation therapy, or an experimental immunotherapy protocol was prompted by identification of new foci of disease. Compared with conventional imaging, FDG-PET provides more accurate assessment of EOD in patients with metastatic melanoma. Significant surgical and medical treatment alterations were made based on PET results.

Adult↗
PubMed2003

Dosimetry-guided radioactive iodine treatment in patients with metastatic differentiated thyroid cancer: largest safe dose using a risk-adapted approach.

UNLABELLED: This study is a retrospective analysis of 124 differentiated thyroid cancer patients who underwent dosimetric evaluation using MIRD methodology over a period of 15 y. The objectives of the study were to demonstrate the clinical use of dosimetry-guided radioactive iodine ([RAI] (131)I) treatment and the safe and effective application of a 3-Gy bone marrow (BM) dose in patients with differentiated thyroid cancer. METHODS: Tumor and BM dose estimates were obtained. The administered activity that would deliver a maximum safe dose to the organ at risk (red BM or lungs) was determined as well as the resulting doses to the metastases. The clinical benefit of an individual RAI treatment was predicted on the basis of the dose estimates and the expected therapeutic response. Each patient's response to treatment was assessed clinically and by monitoring the hematologic profile. RESULTS: One hundred twenty-four patients underwent 187 dosimetric evaluations. One hundred four RAI treatments were performed. A complete response at metastatic deposits was attained with absorbed doses of >100 Gy. No permanent BM suppression was observed in patients who received absorbed doses of <3 Gy to BM. The maximum administered dose was 38.5 GBq (1,040 mCi) with the BM dose limitation. CONCLUSION: Dosimetry-guided RAI treatment allows administration of the maximum possible RAI dose to achieve the maximum therapeutic benefit. Estimation of tumor dose rates helps to determine the curative versus the palliative intent of the therapy.

Adolescent↗
PubMed2003

Optimization of the gamma probe-guided parathyroidectomy.

The objective of this study was to determine the patient-specific optimal time to surgery preoperatively to improve operative success in gamma probe-guided parathyroid localization. Fifteen patients with hyperparathyroidism underwent a double-phase Tc99m-MIBI (15-20 mCi) parathyroid scintigraphy to study the Tc99m-MIBI clearance kinetics from parathyroid and thyroid glands and to determine the time point at which the optimal target-to-background ratio was achieved. Optimal time to surgery was determined on the basis of the time at which the target-to-background ratio was maximal. On the day of surgery the patients received the same dose of Tc99m-MIBI and were taken to the operating room at the time of optimal target-to-background ratio. A four-gland exploration was performed with identification and excision of hot lesions using a gamma probe. Ex vivo lesion-to-background ratios were determined. Histopathologic confirmation of a successful parathyroidectomy was obtained intraoperatively by frozen section. The total operative time and the time to localize and excise the parathyroid glands were recorded. The mean surgery time was compared with that of previous parathyroidectomies performed by the same surgical team without use of preoperative scintigraphy and intraoperative gamma probe. Scintigraphy correctly localized parathyroid pathology in 12 of 15 (80%) patients. Intraoperative gamma probe was successful in 15 of 15 (100%). The optimal time to surgery was found to be different for each patient, and the mean time was calculated as 136 +/- 43 minutes. Mean surgery time for the excision of parathyroid gland was 91 +/- 46 minutes, which was significantly shorter than previous four-gland exploration without use of scintigraphy and gamma probe (160 +/- 61 minutes; t = 3.021, P = 0.007). The mean ex vivo lesion-to-background gamma probe count ratio of abnormal parathyroid glands (77.35) was found to be significantly higher than that of all other lesions with abnormal Tc99m-MIBI uptake (5.05) (U = 10.5, P < 0.0001). Optimal target-to-background ratio is essential for the success of gamma probe-guided parathyroidectomy. This ratio was highly variable among the patients in this study. Individualization of the best surgical exploration time after Tc99m-MIBI injection will improve the surgical success of this operation.

Adult↗
PubMed2003

Preoperative localization and radioguided parathyroid surgery.

Clinical or subclinical hyperparathyroidism is one of the most common endocrine disorders. Excessive secretion of parathyroid hormone is most frequently caused by an adenoma of >or=1 parathyroid gland. Unsuccessful surgery with persistent hyperparathyroidism, due to inadequate preoperative or intraoperative localization, may be observed in about 10% of patients. The conventional surgical approach is bilateral neck exploration, whereas minimally invasive parathyroidectomy (MIP) has been made possible by the introduction of (99m)Tc-sestamibi scintigraphy for preoperative localization of parathyroid adenomas. In MIP, the incision is small, dissection is minimal, postoperative pain is less, and hospital stay is shorter. Localization imaging techniques include ultrasonography, CT, MRI, and scintigraphy. Parathyroid scintigraphy with (99m)Tc-sestamibi is based on longer retention of the tracer in parathyroid than in thyroid tissue. Because of the frequent association of parathyroid adenomas with nodular goiter, the optimal imaging combination is (99m)Tc-sestamibi scintigraphy and ultrasonography. Different protocols are used for (99m)Tc-sestamibi parathyroid scintigraphy, depending on the institutional logistics and experience (classical dual-phase scintigraphy, various subtraction techniques in combination with radioiodine or (99m)Tc-pertechnetate). MIP is greatly aided by intraoperative guidance with a gamma-probe, based on in vivo radioactivity counting after injection of (99m)Tc-sestamibi. Different protocols used for gamma-probe-guided MIP are based on different timing and doses of tracer injected. Gamma-probe-guided MIP is a very attractive surgical approach to treat patients with primary hyperparathyroidism due to a solitary parathyroid adenoma. The procedure is technically easy, safe, with a low morbidity rate, and has better cosmetic results and lower overall cost than conventional bilateral neck exploration. Specific guidelines should be followed when selecting patients for gamma-probe-guided MIP.

Humans↗
PubMed2002

Gamma probe-guided lymph node dissection ('gamma picking') in differentiated thyroid carcinoma.

The prognostic significance and the optimal management of regional lymph node metastases in patients with well-differentiated thyroid carcinoma continue to be controversial. The current surgical approach for nodal metastases is removal of grossly involved lymph nodes ("berry picking"). In patients with papillary thyroid cancer, this intraoperative sampling technique reveals tumor in only 15% to 60% of excised nodes. However, if a more extensive nodal dissection is undertaken, at least 70% of patients are found to have nodal disease. The authors have successfully used a gamma probe-guided lymph node dissection technique ("gamma picking") to identify visually undetectable micrometastatic lymph nodes at the time of surgical exploration. The authors used this technique in a 52-year-old man with papillary carcinoma of the thyroid that was diagnosed by fine-needle aspiration. Eighteen hours before the planned total thyroidectomy, the patient was given 1 mCi I-123 orally. Operative exploration revealed multiple tumor nodules in both lobes but no palpable lymph nodes in the neck. Total thyroidectomy was performed with complete extracapsular removal of both lobes and isthmus. The thyroid bed and the central and lateral nodal basins were scanned using a gamma probe (Neoprobe). Hot spots were identified, and these counts were compared with that of the background activity in the strap muscles. The gamma probe revealed four distinct foci of increased activity (10 times more than the background). These were resected and labeled separately for histopathologic study. Histologic analysis revealed bilateral, multifocal well-differentiated papillary carcinoma, with the largest tumor focus measuring 0.6 cm. Two of the four hot spots proved to be metastatic foci in small lymph nodes measuring less than 0.5 cm. The other two hot spots were thyroid remnants with no associated nodal tissue.

Biopsy, Needle↗
PubMed2002

Cytoreductive surgery in patients with advanced-stage carcinoid tumors.

The role of aggressive surgical resections as well as criteria for resectability in patients with advanced carcinoid tumors is not clearly defined. Thirty patients (17 male and 13 female) who were previously diagnosed to have "unresectable carcinoid disease" were treated using a multimodality approach over a period of 2 years. Extensive liver involvement was present in 28 of 30 (93%) of the cases. Small bowel involvement was noted in 22 of 30 (73%), and peritoneal/retroperitoneal/mesenteric invasion was observed in 15 of 30 (50%) of the cases. Three patients had remote metastases (brain, bone, and eye). Twenty of 30 (66%) patients had carcinoid syndrome with severely disabling symptoms. Eight patients (26%) had small bowel obstruction. All patients underwent at least one surgical exploration/intervention. Radiofrequency ablation (RFA) of one or more liver lesions was performed as an adjunct in 22 of 30 (73%) patients. Six patients (20%) had a second surgical procedure. There were 11 complications in eight patients (27%) after the initial operation. Median hospital stay for patients who underwent RFA only, RFA/liver resection, and liver resection with abdominal tumor debulking were 2, 4, 8, and 16 days respectively. Twenty-five of 30 patients (83%) showed symptomatic improvement. Mean pre- and postoperative Karnofsky physical performance scores were 55 and 85 respectively (P < 0.02). Small bowel obstruction was due to adhesions in five patients. All patients with intestinal obstruction had complete relief of their symptoms postoperatively. 5-Hydroxyindolacetic acid levels decreased by 50 per cent in all patients with follow-up determinations available. Aggressive surgical exploration and tumor debulking could be performed with significantly improved symptomatic outcome and relatively minor complications. Longer follow-up is needed for assessment of effect on survival.

Adolescent↗