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S T Zwas

Publications and source records attributed to S T Zwas.

At least 19 recordsLinked to original sources
PubMed2006

PET/CT in the evaluation of response to treatment of liver metastases from colorectal cancer with bevacizumab and irinotecan.

The present approach at our institution for the treatment of patients with colorectal (CRC) cancer and with liver metastases planned for metastasectomy is the neoadjuvant administration of Bevacizumab with Irinotecan based therapy. Metabolic imaging of tumor viability with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), and simultaneous anatomic localization provided by low-dose non-enhanced computed tomography (CT), can be obtained in a combined modality FDG-PET/CT scan. The purpose of this study was to evaluate the possible contribution of FDG-PET/CT as a surrogate marker to evaluate treatment response of liver metastases in vivo. This is a retrospective evaluation of 18F-FDG PET and CT findings in the first seven consecutive patients. FDG-PET/CT scans were performed before the start of the neoadjuvant and after four cycles of therapy, just prior to surgery. Results were compared to concurrent contrast-enhanced CT, when required, and pathology. Response to treatment was determined according to RECIST size criteria obtained from data from thin (3-5mm) slice CT, and changes in uptake of 18F-FDG uptake on PET. A total of 20 liver lesions were evaluated in seven patients. Overall, 6/7 patients had favorable response to treatment, and only one had progression of disease. One patient was found to be inoperable at surgery. Biopsy was obtained in 1/4 lesions in this patient, while pathology was unable for the remaining three lesions. As such, pathologic validation of findings was available for 17/20 lesions. Complete response (CR) was evident on FDG-PET in 10/17 (58%) lesions, whereas only 4/17(23%) were deemed CR by CT. Similarly, only 1/17 (6%) lesion appeared stable by FDG-PET criteria, whereas three (18%) were termed stable disease (SD) according to size on CT. FDG-PET findings correlated better than CT with pathology, and were more indicative of pathology. Overall PET/CT correctly predicted necrosis at pathology in 70% vs. 35% by CT. Our results suggest that 18F-FDG PET may be instrumental for predicting the pathologic response to Bevacizumab based therapy.

Adult↗
PubMed2006

PET/CT detects abdominal wall and port site metastases of colorectal carcinoma.

Abdominal wall metastases from colorectal cancer (CRC) may be resected with curative results. Such lesions, often indicators of additional intra-abdominal lesions, may appear in surgical scars, stomas and port site metastases after laparoscope-assisted surgery (LAS). Post-operative changes, primarily surgical scars, alter local physical findings making early detection of small lesions challenging. The purpose of this study was to retrospectively evaluate the contribution of PET/CT to the diagnosis of recurrent colorectal cancer in the post-operative abdominal wall. 120 patients were referred for PET/CT with suspected recurrent CRC based on clinical, radiological or laboratory findings. All underwent whole body PET/CT imaging. 12 of these 120 (10%), were found to have abdominal wall lesions. A total of 16 abdominal wall lesions were detected, located to surgical scars, stomas, drain and laparoscope ports. Additional findings on PET/CT in this group included liver metastases, intra-abdominal lesions and retroperitoneal lymph node involvement. In general, the patients in this small group were young with high grade tumours presenting in advanced stages. In conclusion, PET/CT appears to be a sensitive tool for the diagnosis of abdominal wall recurrence of CRC. The accuracy of localization afforded by the fused functional and anatomic images makes PET/CT a likely tool for diagnosing abdominal wall lesions, including port site metastases of other aetiologies.

Abdominal Wall↗
PubMed2005

PET/CT in the evaluation of patients with squamous cell cancer of the head and neck.

The purpose of this study was to compare the findings of positron emission tomography (PET) with fused PET and computed tomography (CT) in patients with suspected locoregional and distant head and neck cancer and to evaluate the impact of those findings on clinical management. Studies of 25 patients were retrospectively evaluated. PET findings were classified as malignant, benign or equivocal. PET/CT findings were then similarly classified and the PET-only results were amended accordingly. Comparison of findings was done on lesion and patient levels. A total of 45 foci of increased 18F-fluorodeoxyglucose (FDG) uptake were noted in 18 patients. PET/CT imaging defined anatomic localization of 41/45 lesions and clarified 6/10 equivocal PET findings. Additional information was provided by PET/CT regarding 9/45 (20%) of the lesions. PET/CT significantly affected patient management in 3/25 patients (12%) by limiting the extent of disease in one and excluding viable disease in two others. The accuracy of PET/CT was 88%, the sensitivity 100% and the specificity was 77%. The negative predictive value was 100% in this combined group of patients with locoregional and distant head and neck cancer. PET/CT is highly contributory for initial staging and in the evaluation of patients with suspected recurrent SCC of the head and neck, in whom anatomic imaging is inconclusive due to the locoregional distortions rendered by surgery and radiotherapy.

Adolescent↗
PubMed2005

The role of gamma-PET in the evaluation of patients with recurrent squamous cell cancer of the head and neck.

Squamous cell carcinoma (SCC) is the most common cancer of the head and neck (HNC). Advanced HNC warrants extensive ablative and reconstructive procedures, significantly altering locoregional anatomy, while radiation treatment further adds to the distortion. Anatomic imaging is therefore often inconclusive in suspected recurrent HNC. Functional imaging with fluorodeoxyglucose-positron emission tomography (FDG-PET) has been reported contributory in the evaluation of patients with SCC. While most reports are from dedicated PET systems, full ring PET is of limited availability and gamma-PET may offer a suitable compromise. The therapeutic impact of gamma-PET in patients with suspected recurrent HNC was retrospectively evaluated. Seventeen patients were evaluated. All had undergone surgery for HNC, 16 also received radiotherapy. gamma-PET scans were compared to anatomic imaging, histopathology and clinical follow-up. The impact of the FDG-PET scan on patient management was then evaluated. Eleven positive findings were confirmed. Two false positives were due to radiation changes, a recognized pitfall. There were no false negatives. Overall accuracy of the 18F-FDG gamma-PET scans was 88% with considerable effect on patient management. Gamma-PET with FDG appears valuable in the evaluation of suspected recurrent HNC, and may provide a suitable alternative when dedicated PET is unavailable.

Adolescent↗
PubMed2003

140 consecutive cases of minimally invasive, radio-guided parathyroidectomy: lessons learned and long-term results.

BACKGROUND: The advent of highly accurate parathyroid imaging and the ever-increasing trend towards minimally invasive procedures have changed considerably the surgical approach to the patient with primary hyperparathyroidism (PHPT) caused by a single parathyroid adenoma. This study analyzes the short- and longer-term results of 140 patients who underwent minimally invasive, radio-guided parathyroidectomy. METHODS: Demographic, clinical, and pre-operative imaging data, operative findings, and short- and long-term results of 140 consecutive patients operated within a 20 months period (8/1999-4/2002), were prospectively entered into a database. Immediate pre-operative sestamibi scintigraphy with skin marking of focal adenoma uptake were followed by intraoperative hand-held gamma probe for the removal of the parathyroid adenoma by unilateral minimal access surgery. Preoperative and surgical data were analyzed and correlated to outcomes, measured by success or failure to cure PHPT, associated morbidity and mortality, predictive value of localizing studies, and postoperative laboratory results in the immediate as well as long-term period. RESULTS: 140 patients, mean age: 55.1 +/- 14.1 years (range 19-88 years), female to male ratio 94:46 with PHPT proven by concomitantly elevated serum calcium and parathormone (PTH) levels, with a single adenoma identified by sestamibi single photon emission tomography (SPECT) scintigraphy and high-resolution sonography, underwent minimally invasive, radio-guided parathyroidectomy. Mean serum levels of preoperative calcium, phosphorus, and PTH were 11.6 +/- 0.8 mg/dL (range 9.1-14), 3.0 +/- 0.3 mg/dL, and 147.1 +/- 94.3 pg/mL (range 68-784), respectively. Overall, in 3 out of 140 patients (2.1%), focused, minimally invasive surgery failed to identify and remove the adenoma. Positive predictive value when both localizing modalities concurred was 99.2%. Positive predictive value of SPECT scan alone was 97.2%. Overall success rate was 97.8% (137/140). 24 hours postoperative mean serum calcium was 9.2 +/- 0.8 mg/dL and at 6 months mean serum calcium, phosphorus, and PTH were 9.4 +/- 1.06 mg/dL, 3.2 +/- 0.8 mg/dL, and 32.1 +/- 11.9 pg/mL, respectively (p = 0.0001). There was no mortality. In 2 patients (1.4%) there was transient vocal cord paresis and there were 8 instances of clinically significant hypocalcemia. In 3 cases (2.1%), a second adenoma manifested itself 9-14 months following surgery and was removed by minimal access procedure. CONCLUSIONS: Minimally invasive, radio-guided focused parathyroidectomy for a single adenoma is safe and effective in curing hyperparathyroidism with a 97% success rate. A second adenoma occurring in less than 3% may be successfully treated with a second minimal access operation. The combined positive predictive value of concurring sestamibi SPECT scintigraphy and sonography of 99.2% may increase success rate, and thus implementing this technique in patients with concurring sonography and scintigraphy may be advocated.

Adenoma↗
PubMed2003

The clinical impact of 18F-FDG gamma PET in patients with recurrent well differentiated thyroid carcinoma.

The therapeutic approach to recurrent well-differentiated thyroid cancer is based on the detection of active disease. While a measured increase of thyroglobulin level in an ablated patient is highly suggestive of recurrence, localization of the tumour is necessary for adequate treatment planning. A whole body scan with 131I yields false negative results in the presence of non-iodophyllic foci of disease. Hypermetabolic foci of differentiated thyroid carcinoma can be detected by gamma PET with 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG). This study retrospectively evaluated the therapeutic impact of the 18F-FDG scan in patients with suspected recurrent thyroid carcinoma in whom the iodine scan was negative. Twenty patients (five male, 15 female) aged 19-77 years, were suspected of having recurrent thyroid carcinoma due to elevated thyroglobulin levels and/or palpable neck findings. All whole body iodine scans obtained with diagnostic doses (74-148 MBq (2-4 mCi) of 131I), were reported normal, i.e., no iodophyllic foci were detected. Whole body gamma positron emission tomography (PET) imaging was performed in fasting patients following i.v. administration of 370 MBq (10 mCi) 18F-FDG, with a strict 1 h immobilization post-injection. Gamma PET results were validated either by anatomical imaging, repeat iodine scanning after administration of a therapeutic dose (at least 3,700 MBq (100 mCi) of 131I) or surgery. The impact of the FDG scan on patient management was evaluated by the referring physicians. Positive gamma PET results confirmed the presence of active disease in 14/15 patients. One false positive finding (fibrosis) and one false negative (carcinoid) were reported. Localization of hypermetabolic foci supported treatment decisions in 10 patients, and significantly altered therapeutic management in six others. Treatment was withheld in four patients with negative findings. The clinical impact of the scan in this patient group is similar to that reported in the literature and justifies its future implementation.

Adult↗
PubMed2003

Focused, minimally invasive radio-guided parathyroidectomy: a feasible and safe option for elderly patients with primary hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism in elderly patients is usually associated with additional co-morbidity that increases operative risk, and thus many geriatric patients are denied the benefit of surgery for a single parathyroid adenoma. OBJECTIVES: To evaluate the safety and efficacy of accurate single photon emission computed tomography sestamibi scintigraphy, enabling precise localization of a single adenoma, in the geriatric population. METHODS: Twenty-two patients aged 70 years and over with biochemically proven PHPT and with a single parathyroid adenoma identified by localization studies (sestamibi SPECT scan and ultrasonography) underwent 23 operations over 29 months (out of a total of 140 patients operated upon during the same period). Immediate preoperative sestamibi scintigraphy and marking of focal adenoma uptake followed by intraoperative hand-held gamma probe were used for the removal of the parathyroid adenoma by unilateral minimal access surgery. Associated major co-morbid conditions and pre- and postoperative calcium, phosphorus and parathormone levels were recorded. Indications for surgery were listed and operative and postoperative complications were noted. The patients were followed for a mean period of 17.7 months using the same parameters. RESULTS: The 22 patients with PHPT had a mean age of 76.3 +/- 5.9 years (range 70-88 years) and a female to male ratio of 13:9. Associated co-morbidity included ischemic heart disease (n = 15), hypertension (n = 22), non-insulin-dependent diabetes mellitus (n = 9), chronic obstructive pulmonary disease (n = 3), and previous neck surgery (n = 3). Mean preoperative serum calcium, phosphorous and PTH were 11.7 +/- 1.3 mg/dl, 2.5 +/- 0.5 mg/dl and 160.9 +/- 75.4 pg/ml respectively. In 20 of the 22 patients, surgery was successful in curing PHPT (91%). One patient had persistent hypercalcemia due to a missed adenoma, and repeat operation (by focused minimal accesss surgery) was successfully performed 2 weeks later. There were no complications and no morbidity postoperatively. Mean postoperative serum calcium, phosphorous and PTH were 9.6 +/- 1.2 mg/dl, 3.0 +/- 0.5 mg/dl and 35.2 +/- 24 pg/ml respectively. In all patients, serum calcium levels remained normal (9.7 +/- 1.3 mg/ml) after long-term follow-up (mean 17.7 +/- 9.6 months). CONCLUSIONS: Minimally invasive, radio-guided focused parathyroidectomy for a single adenoma is a safe and effective method to cure hyperparathyroidism in the elderly. Success of surgery is directly related to the surgeon's experience and to the precise localization marking provided by sestamibi scintigraphic SPECT localization and concurrent sonographic findings.

Adenoma↗
PubMed2000

Bilateral accessory iliac horns: pathognomonic findings in Nail-patella syndrome. Scintigraphic evidence on bone scan.

Nail-patella syndrome is a rare hereditary (autosomal dominant) disorder, also called hereditary osteo-onychodysplasia and Fong's syndrome. Its incidence is 4.5 per million population in the United States. Patients have a characteristic tetrad of pathologic symptoms including fingernail dysplasia, hypoplastic or absent patellas, radial head dislocation, and iliac horns. Soft-tissue changes and renal dysplasia have also been associated with the syndrome. Iliac horns are bilateral accessory outgrowths consisting of cortex and medulla continuous with the iliac bone. They are located at the site of attachment of the gluteus medius muscles and project posterolaterally. These smooth bony outgrowths are asymptomatic, frequently palpable, and, because they have no effect on gait, they need not be treated. Iliac horns are the pathognomonic feature of Nail-patella syndrome; that is, they occur in approximately 80% of cases and are observed only in this condition. Four patients (two female, two male) with Nail-patella syndrome have been examined in the authors' department: three family members, including a 37-year-old woman, her 18-year-old son, and her 15-year-old daughter, and an unrelated 26-year-old man. All patients, regardless of age or sex, had similar pelvic findings on their bone scans. Although whole-body scans were obtained in all patients, significant scintigraphic findings were observed only in the pelvis in all the patients examined. This is most likely the result of the mild nature of the related deformities, which do not yield scintigraphically detectable osteoblastic changes. A representative image showing these independent ossification on a Tc-99m MDP bone scan is presented. A conventional pelvic radiographic image of the same patient's pelvis is presented for comparison.

Adolescent↗
PubMed1999

Evidence for striatal modulation in the presence of fixed cortical injury in obsessive-compulsive disorder (OCD).

A patient with obsessive-compulsive disorder (OCD) onset resulting from a traumatic head injury underwent longitudinal brain imaging evaluation. Structural and functional brain imaging studies were repeatedly performed before and after treatment. Computerized tomography (CT) demonstrated bilateral prefrontal contusions immediately following the trauma and prior to the onset of OCD. Magnetic resonance imaging (MRI) demonstrated bilateral cortical abnormalities in the prefrontal and anterior-temporal regions a few months following the onset of OCD. Almost concurrently, single photon emission computerised tomography (SPECT) demonstrated bilateral perfusion deficits in fronto-temporal regions, and asymmetric increased perfusion in the anterior striatum. Six months later, after clinical improvement, a second SPECT study demonstrated improvement of brain perfusion, mostly in the striatum. The reflection of these results on a possible model of brain pathogenesis in OCD, and the role of brain imaging in neuropsychiatric evaluation, are demonstrated.

Adult↗
PubMed1998

Renal depth estimates to improve the accuracy of glomerular filtration rate.

UNLABELLED: This study was performed to validate a computer implementation of the Gates' method for radionuclide glomerular filtration rate (RGFR) calculation. The accuracy of the original method was improved by replacing the Tonnesen formula that estimated renal depth with direct measurement from lateral views to calculate tissue attenuation correction. METHODS: Both the creatinine clearance test (CCT) and dynamic 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal scintigraphy (DRS) were performed on 38 patients on the same day. RGFR was quantified from the attenuation corrected absolute DTPA uptake of the kidneys on DRS from 120-180 sec after injection. Attenuation correction was estimated using the lateral views of the kidneys taking in account the distance from the computed geometric center of the kidneys to the posterior body surface along a line vertical to the collimator surface. CCT and glomerular filtration rate estimates from DRS were compared by linear regression. RESULTS: RGFR estimates agreed well with CCT, yielding a correlation coefficient of 0.92 in 38 patients and 0.90 in a subgroup of 11 patients suffering from chronic renal failure. CONCLUSION: Present modifications improve RGFR accuracy to the precision range of blood sample based methods. This modified method requires little additional work and no extra cost in patients undergoing DRS. RGFR calculation may be advantageous in cases when 24-hr urine collection for CCT cannot be obtained, and it should improve the accuracy of the captopril test.

Adult↗
PubMed1997

Benign osteonecrosis of the external ear canal.

Benign osteonecrosis (BON) of the external ear canal (EEC), also termed as focal or circumscribed necrotizing lesion, is an infrequent phenomenon with distinctive features and of an obscure origin. Five patients with BON of the EEC presented with aggressiveness and extension of varying degree including involvement of the middle ear. It seems that the disease might have a self limited course (two patients) though, at times, extensive measures including hyperbarric oxygen therapy (one patient) should be applied.

Adult↗
PubMed1997

Silicone suspension of external prostheses. A new era in artificial limb usage.

The use of silicone inner sockets, with or without the incorporation of shuttle locks, has greatly improved the function of artificial limbs. They cushion and protect the stump and provide a means for prosthetic suspension, allowing more comfortable use, especially in patients with ischaemic stumps. They also allow greater movement at the proximal joint.

Adult↗
PubMed1996

The role of 99Tcm-HMPAO brain SPET in paediatric traumatic brain injury.

Twenty-eight paediatric patients suffering from chronic sequelae of traumatic brain injury (TBI) were examined by EEG, radionuclide imaging with 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO), computed tomography (CT) and, when available, magnetic resonance imaging (MRI), the results of which were evaluated retrospectively. Our findings indicate that neuro-SPET (single photon emission tomography) with 99Tcm-HMPAO is more sensitive than morphological or electrophysiological tests in detecting functional lesions. In our group, 15 of 32 CT scans were normal, compared with 3 of 35 SPET studies. SPET identified approximately 2.5 times more lesions than CT (86 vs 34). SPET was found to be particularly sensitive in detecting organic abnormalities in the basal ganglia and cerebellar regions, with a 3.6:1 detection rate in the basal ganglia and a 5:1 detection rate in the cerebellum compared with CT. In conclusion, neuro-SPET appears to be very useful when evaluating paediatric post-TBI patients in whom other modalities are not successful.

Adolescent↗