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Kathryn A Morton

Publications and source records attributed to Kathryn A Morton.

8 recordsLinked to original sources
PubMed2006

Reversal of hypermetabolic brown adipose tissue in F-18 FDG PET imaging.

OBJECTIVES: With the increasing application of F-18-fluorodeoxyglucose (FDG) positron emission imaging, there has been an evolving appreciation for the range of normal variants and the realization that false-positives can lead to serious consequences. RESULTS: One of the most common causes of a false-positive study is the uptake of FDG in areas of hypermetabolic brown adipose tissue (HBAT). Areas of involvement are often spatially closely related to important lymph node groups in the neck, axilla, and upper mediastinum, making critical differentiation difficult, even with PET-CT. CONCLUSIONS: FDG uptake in HBAT has been noted to occur more frequently in cold months and benzodiazepines have been proposed for its prevention. The use of these drugs is, in our experience, of limited value and may complicate patient care in both inpatient and outpatient populations. In this report, we describe considerable success by completely reversing HBAT in 9 of 10 sequential patients with simple core warming maneuvers, which obviate the use of benzodiazepines.

Adipose Tissue, Brown↗
PubMed2005

The scintigraphic appearance of subcapsular parathyroid adenomas.

PURPOSE: Approximately 5 to 10% of parathyroid adenomas are located within the thin, fibrous capsule of the thyroid gland. These subcapsular adenomas can complicate minimally invasive parathyroidectomy. The small incision used in this procedure limits the view of the surgical bed. Palpation is less sensitive when the adenoma is covered by the thyroid capsule. If a subcapsular parathyroid adenoma can be identified on preoperative parathyroid scintigraphy, nuclear medicine physicians can recommend exploration of the thyroid capsule early, leading to an easier, more efficient operation. The objective of this observational study was to identify the scintigraphic appearance of subcapsular parathyroid adenomas. MATERIALS AND METHODS: A total of 109 patients with primary hyperparathyroidism underwent preoperative dual-phase Tc-99m sestamibi parathyroid scintigraphy at our tertiary care center from October 2002 to March 2004. Tc-99m pertechnetate was used as a supplemental technique when deemed necessary for optimal interpretation. Retrospective chart review identified 16 surgically proved subcapsular parathyroid adenomas. Parathyroid scintigraphy was reviewed. RESULTS: Subcapsular parathyroid adenomas tend to conform to the expected shape of the thyroid gland. In this small series, subcapsular parathyroid adenomas followed 1 of 3 patterns on lateral images: (1) focal convex distortion of the posterior wall of the thyroid, (2) polar lentiform configuration, and (3) compression of the posterior thyroid parenchyma. CONCLUSION: Subcapsular parathyroid adenomas often have a distinct appearance on scintigraphy. Preoperative identification of this type of parathyroid adenoma can direct a subcapsular surgical approach, optimizing the efficiency of the minimally invasive parathyroidectomy.

Adenoma↗
PubMed2005

Evaluation of liver metastases after radiofrequency ablation: utility of 18F-FDG PET and PET/CT.

OBJECTIVE: Our objective was to review the CT appearance of liver metastases after radiofrequency ablation and to describe the imaging findings of and utility of (18)F-FDG PET and PET/CT in assessing tumor recurrence after ablation. CONCLUSION: (18)F-FDG PET and PET/CT can provide added diagnostic information compared with conventional imaging in patients after radiofrequency ablation of liver metastases and can be useful in guiding repeat ablation procedures.

Catheter Ablation↗
PubMed2005

Development of a finite element-based injury metric for pulmonary contusion part I: model development and validation.

Pulmonary contusion is the most commonly identified thoracic soft tissue injury in an automobile crash and after blunt chest trauma and affects 10-17% of all trauma admissions. The mortality associated with pulmonary contusions is significant and is estimated to be 10-25%. Thus, there is a need to develop a finite element model based injury metric for pulmonary contusion for the purpose of predicting outcome. This will enable current and future finite element models of the lung to incorporate an understanding of how stress and strain may be related to contusion injuries. This study utilizes 14 impacts onto male Sprague-Dawley rats. In 5 of these tests, a calibrated weight (46 g) is dropped from a height of 44 cm directly onto the lungs of intubated, anesthetized rats in situ. Contused volume is estimated from MicroPET scans of the lung and normalized on the basis of liver uptake of 18F-FDG. The lungs are scanned at 24 hours, 7 days, and 28 days (15 scans), and the contused volume is measured. In addition, 9 controlled mechanical tests on in situ rat lung are used for model development and validation. Identical impacts are performed on a finite element model of the rat lung. The finite element model is developed from CT scans of normal rat and scaled to represent average rat lung volume. First principal strain is chosen as a candidate injury metric for pulmonary contusion. The volume of contused tissue at the three time points measured using PET is compared to the strain level achieved by a corresponding volume in the finite element model. For PET scans (n=5 scans per time point), the average contusion volume was 4.2 cm3 at 24 hours, 2.8 cm3 at 7 days, and 0.39 cm3 at 28 days. These volumes were used to identify threshold peak first principal strain levels measured by the finite element model. Maximum first principal strain from the finite element model for the three volume levels (4.2, 2.8, and 0.39 cm3) was 3.5%, 8.8%, and 35% strain, respectively. Furthermore, the lung model exhibited exponential decay in principal strain threshold as more of the lung volume was considered, correlating to the precise and well defined volume of the contusion as it healed. The results of this study may be used to establish an injury metric to predict pulmonary contusion due to an impact to the lungs. The results may be used to improve finite element models of the human body, which may then be used to tune stiffnesses of interior components of automobiles and tune safety systems for maximum mitigation of this serious injury.

Journal Article↗
PubMed2003

Enhanced scintigraphic protocol required for optimal preoperative localization before targeted minimally invasive parathyroidectomy.

At our tertiary care institution, a targeted minimally invasive parathyroidectomy (MIP) is the preferred surgical procedure for primary hyperparathyroidism. Similar to unilateral neck exploration (UNE), preoperative scintigraphic localization of the adenoma in relation to the midline is required. However, in contrast to the abbreviated standard incision for UNE, 2 distinct incision sites, 1 medial and 1 lateral, are available on each side with MIP. The incision site is ultimately chosen based on scintigraphic determination of the adenoma's vascular origin to facilitate ligation and removal. Unfortunately, the scintigraphic location of a parathyroid adenoma does not necessarily reflect the site of its vascular origin. We reviewed our database to identify factors that accurately predict the site of vascular origin of parathyroid adenomas. A retrospective chart review was performed on 125 patients who underwent Tc-99m sestamibi scintigraphy and parathyroidectomy. Scintigraphic localization, surgical findings, and histopathology were recorded. Preoperative image interpretations that were discordant with operative findings were independently reviewed. Scintigraphy identified the presence of an adenoma in 105 of 118 patients (89%) with primary hyperparathyroidism. In 17 of the 105 cases (16%), the scintigraphic interpretation did not accurately reflect the site of superior or inferior vascular origin seen at surgery. In many discordant cases, anterior images were insufficient for determining the vascular origin. The posterior displacement of an adenoma in relation to the thyroid on early lateral images was often critical in determining the superior or inferior vascular origin. Scintigraphic determination of the superior or inferior vascular origin of a parathyroid adenoma directs incision placement for MIP. Imaging protocols should include early lateral images when localizing parathyroid adenomas before minimally invasive parathyroidectomy.

Adenoma↗
PubMed2003

Experienced scintigraphers contribute to success of minimally invasive parathyroidectomy by skilled endocrine surgeons.

Minimally invasive parathyroidectomy (MIP) has become the preferred surgical treatment for selected patients diagnosed with primary hyperparathyroidism (PHPT) at our tertiary-care center. Preoperative scintigraphy establishes the position of a parathyroid adenoma, dictates the incision site, and can minimize incision size and consequent tissue dissection. We reviewed our database and sought to identify factors that led to discordant preoperative imaging and operative findings and to assess the effect of experience on these findings. A retrospective review was performed on all patients with biochemically proven PHPT who underwent Tc-99m sestamibi scintigraphy and surgical intervention. Patient demographics, date of surgical intervention, scintigraphic localization, surgical findings, pre- and postoperative biochemical markers, histopathology, coexisting thyroid pathology, and 6-month follow up were recorded. Preoperative images that were discordant with operative findings were independently reviewed. Parathyroid scintigraphy was performed on 125 consecutive patients for PHPT between November 1999 and January 2002. Seventy-six patients had MIPs, 35 had standard cervical explorations, 11 had MIPs that were converted to standard cervical explorations, and three had surgery directed to an ectopic location. At 6-month follow-up 98.4 per cent were cured. Preoperative imaging and surgical findings were ipsilateral and concordant in 105 of 118 (89%) patients with parathyroid adenoma. The anatomic origin of an adenoma was predicted in only 83 of 118 (68%) patients. Most of the inaccurate scintigraphy readings occurred during the first 13 of the 26 months that MIPs were performed at our institution. Only two discordant cases occurred during the last 9 months of this period. Biochemical markers, prior neck operation, and concomitant thyroid pathology had no correlation with imaging sensitivity. Scintigraphic interpretation of smaller adenomas was less reliable; discordant cases were more common in small adenomas. Communication between endocrine surgeons and nuclear medicine physicians about the MIP technique and anatomic orientation of adenomas led to better scintigraphic localization as experience increased. Now that MIP by skilled endocrine surgeons is becoming the favored treatment for PHPT experienced nuclear medicine physicians may be the most important factor to achieve maximum success.

Adenoma↗
PubMedDate not supplied

Evaluation of the quantitative capability of a high-resolution positron emission tomography scanner for small animal imaging.

OBJECTIVE: The quantitative capability of a positron emission tomography scanner for small animal imaging was evaluated in this study. METHODS: The microPET P4 (Concorde Microsystems, Knoxville, TN) scanner's capability for dynamic imaging and corrections for radioactive decay, dead time, and attenuation were evaluated. Rat brain and heart studies with and without attenuation correction were compared. A calibration approach to convert the data to nanocuries per milliliter was implemented. Calibration factors were determined using calibration phantoms of 2 sizes with and without attenuation correction. Quantitation was validated using the MiniPhantom (Data Spectrum, Chapel Hill, NC) with hot features (5:1 ratio) of different sizes (4, 6.4, 8, 13, and 16 mm). RESULTS: The microPET P4 scanner's ability to acquire dynamic studies and to correct for decay, dead time, and attenuation was demonstrated. The microPET P4 scanner provided accurate quantitation to within 6% for features larger than 10 mm. Sixty percent of object contrast was retained for features as small as 4 mm. CONCLUSIONS: The microPET P4 scanner can provide accurate quantitation.

Animals↗