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Biomedical subjects

M McBiles

Publications and source records attributed to M McBiles.

11 recordsLinked to original sources
PubMed2000

Coping with PACS downtime in digital radiology.

As radiology departments become increasingly reliant on picture archiving and communication systems, they become more vulnerable to computer downtime that can paralyze a smoothly running department. The experiences and strategies developed during various types of picture archiving and communication system (PACS) downtime in a large radiology department that has completely converted to soft copy interpretation in all modalities except mammography are presented. Because these failures can be minimized but not eliminated, careful planning is necessary to minimize their impact.

Equipment Failure↗
PubMed1999

Acute effect of nicotine patch on gastric emptying of liquid and solid contents in healthy subjects.

The effect of nicotine on gastric emptying remains controversial. Gastric emptying is delayed in chronic smokers after smoking high-dose nicotine cigarettes, but it is unchanged after chewing nicotine gums. No information is available on the effect of transdermal nicotine patches on the gastric emptying of solid and liquid contents in healthy nonsmokers. Our objective was to prospectively evaluate the effect of the nicotine patch on gastric emptying of liquid and solid contents in healthy nonsmokers. Ten healthy nonsmoking volunteers underwent a baseline dual-isotope gastric scintigraphy with [111In]-diethylenetriaminepantaacetic acid (DTPA) and [99mTc]sulfur colloid isotopes to evaluate prospectively the gastric emptying of liquid and solid contents, respectively. The gastric scintigraphy was repeated after placing a transdermal nicotine patch (Habitrol) for 12 hr designed to deliver 14 mg of nicotine per day. Plasma nicotine level was measured prior to baseline gastric scintigraphy and after 12 hr placing the nicotine patch. Plasma nicotine was absent in all subjects at baseline and but was significantly elevated after 12 hr of nicotine patch (P < 0.009). The mean half-emptying times (T1/2) for the gastric emptying of liquids before and after nicotine patch placement were 31.2+/-23.3 and 25.6+/-8.4 min, respectively (P = 0.498). The mean T1/2s for the gastric emptying of solids before and after nicotine patch placement were 70.1+/-34.0 and 59.7+/-31.4 min, respectively (P = 0.202). There was no correlation between the plasma nicotine level and gastric emptying of liquid and solid contents (correlation coefficient = -0.23 and -0.01, respectively). In conclusion, acute transdermal delivery of nicotine does not affect the gastric emptying of solid and liquid contents in healthy nonsmoking subjects.

Administration, Cutaneous↗
PubMed1997

The impact of a picture archiving and communication system on nuclear medicine examination interpretation.

Radiographic correlation is essential for many of the examinations performed in nuclear medicine. The purpose of this study was to evaluate the impact of a picture archiving and communications system (PACS) on the function and efficiency of a nuclear medicine department at a tertiary care institution. We evaluated 250 consecutive noncardiac nuclear medicine imaging examinations and asked the interpreting physician the following questions: (1) Was PACS used in the interpretation of the study? (2) Did the use of PACS expedite examination completion or aid in study interpretation? And (3) Did the use of PACS permit a definitive diagnosis to be made? PACS was accessed for correlative radiographic images in 155 of the 250 (62%) nuclear medicine examinations. Images available on PACS for review aided in study interpretation in 74% (115 of 155) of cases. The use of PACS was thought to expedite examination completion in 55% (86 of 155) of cases. The system was accessed but not operational in only 1% of cases (2 of 155). PACS provides reliable, rapid access to multimodality correlative radiographic images that aid in the interpretation of nuclear medicine examinations. Such systems also increase the efficiency of a nuclear medicine service by allowing timely and conclusive interpretations to be made.

Evaluation Studies as Topic↗
PubMed1997

Indium In-111 pentetreotide scintigraphy: application to carotid body tumors.

PURPOSE: This study was conducted to investigate and illustrate the use of Indium In-111 pentetreotide scintigraphy as it applies to carotid body tumors (CBT). Localization has relied primarily on ultrasonography, computed tomography, and magnetic resonance imaging with angiographic confirmation. These methods only assess the cervical bifurcation without providing an evaluation of metastasis in patients without symptoms or recurrence in patients after surgery. METHODS: Indium In-111 pentetreotide scintigraphy was used in five patients with a diagnosis of CBT. Four patients were evaluated after surgical excision for evidence of tumor recurrence. One patient was evaluated before excision for diagnostic confirmation. RESULTS: No evidence of tumor recurrence was demonstrated in the four patients who had undergone previous CBT excision. One of these patients had increased activity in the pituitary, later confirmed as an enlarged pituitary without evidence of an adenoma with computed tomography. The diagnosis of CBT was confirmed in the patient evaluated before surgery. This patient also had increased activity in the occipital region, confirmed as the site of previous ischemia on computed tomography. CONCLUSION: Indium In-111 pentetreotide scintigraphy is a new innovative method for viewing neuroendocrine tumors. Its potential lies not only in tumor localization but also in identification of recurrent tumor at the operative site and metastatic disease.

Carotid Body↗
PubMed1995

Sestamibi parathyroid imaging.

Since the introduction of technetium-99m (99mTc) sestamibi (hexakis-2-methoxyisobutyl isonitrile) as a parathyroid imaging agent in 1989, many investigators using several different imaging protocols have reported uniformly excellent results for localization of parathyroid adenomas. Exact localization of hyperplastic parathyroid glands has not met with as much success. However, the results of multiple comparative studies suggest that the diagnostic utility of sestamibi protocols equals or exceeds other noninvasive, nonscintigraphic imaging strategies, including high-resolution ultrasound, computed tomography, and magnetic resonance imaging. Two different, but not necessarily mutually exclusive imaging strategies have been used: subtraction imaging using iodine-123 (123I) or 99mTc sodium pertechnetate as the thyroid agent, and sestamibi dual-phase imaging, which takes advantage of differential washout of sestamibi from thyroid and parathyroid tissue. Sestamibi subtraction imaging has been shown to have greater sensitivity for abnormal parathyroid glands compared with thallium-201 subtraction imaging using pooled data, 87% versus 71%, respectively. Dual-phase sestamibi imaging protocols are much more variable in their conduct and have a much greater variability in sensitivity, 43% to 91%, but with a pooled sensitivity of 73%. Data suggest that dual phase techniques are at least as sensitive, and in optimized protocols, superior to, thallium-201 subtraction techniques. This superiority is attributed to the favorable washout kinetics of sestamibi and the superior imaging characteristics of the 99mTc label. Specificity and positive predictive value for both sestamibi techniques are very high, typically greater than 90% and at least equal to thallium-subtraction protocols, although specificity may be slightly lower for sestamibi subtraction techniques. Therefore, sestamibi protocols are the scintigraphic procedure of choice for parathyroid imaging. Dual-phase sestamibi protocols are more robust and lend themselves to single photon emission computer tomography (SPECT) imaging, and may be followed sequentially by subtraction techniques if results are inconclusive. Despite the excellent results of sestamibi parathyroid imaging, it is unclear whether this accuracy can compete with the even better success of an experienced surgeon in initial surgeries for hyperparathyroidism, and routine preoperative imaging before initial surgery is still controversial. However, sestamibi parathyroid imaging is an excellent addition to a correlative imaging approach in reoperations for persistent and recurrent hyperparathyroidism.

Adenoma↗
PubMed1994

Correlative imaging of the kidney.

The proliferation of imaging methods for the kidney and urinary tract, combined with advances in technology and the introduction of new techniques, has created uncertainty in selecting the most efficient method for evaluating many problems encountered in clinical medicine. The main advantage of nuclear medicine lies in demonstrating the pathophysiology involved. Recent developments in Doppler ultrasound and magnetic resonance imaging with different pulse sequences and paramagnetic contrast agents also have shown promise for imaging physiological processes. However, there is little literature to support their advantage over nuclear medicine procedures in many common clinical situations. The complementary nature of nuclear medicine studies in the imaging evaluation of hydronephrosis, renal artery stenosis, flank pain, renal mass, pyelonephritis, and the transplant kidney is reviewed.

Adult↗
PubMed1992

Measurement of glomerular filtration rate in ICU patients using 99mTc-DTPA and inulin.

Improved and reliable methods for assessing glomerular filtration rate (GFR) in intensive care patients are needed in light of known deficiencies using creatinine clearance. We compared simultaneous two-hour clearances of inulin (CIn), creatinine (CCr), and 99mTc-diethylenetriaminepentaacetic acid (CDTPA) in 18 medical or surgical intensive care patients (range, 49 to 92 years old) with blood urea nitrogen (BUN) levels greater than 17.9 mmol/liter (0.5 mg/ml), serum creatinine levels greater than 150 mumol/liter (0.02 mg/ml), or estimated Cockcroft clearance less than 60 ml/min. Patients had severe renal dysfunction with average GFR of 35 ml/min (range, 2 to 69 ml/min). CDTPA and CCr correlated significantly with CIn, although CDTPA tended to provide a closer approximation. Cockcroft clearance (32 +/- 4 ml/min) was grossly similar to CDTPA and CIn and correlated significantly, especially when weight was calculated using actual as opposed to ideal body weight. In a subset of 13 patients with CIn less than 30 ml/min, only CDTPA was significantly correlated with CIn. In patients in the intensive care unit, CDTPA provides a rapid, accurate, and inexpensive clinical assessment of GFR, even at very low GFRs.

Aged↗
PubMed1990

An easy method for diagnosis of lymphedema.

Lymphoscintigraphy has been very useful in determination of lymphatic abnormalities. However, the radioactive isotopes used have been investigational and difficult obtain. The purpose of this study was to examine patients with extremity edema by lymphoscintigraphy using a radioactive colloid readily available in our nuclear pharmacy, Technetium 99m sulfur minicolloid. Forty limbs in 20 patients were evaluated using Technetium 99m sulfur minicolloid lymphoscintigraphy. All patients had lower extremity edema initially attributed to a venous or lymphatic etiology. There were 12 patients with normal bilateral studies. Seven patients exhibited unilateral obstruction to lymphatic flow, and one had unilateral enhanced flow of lymph. Those with normal studies included five patients with nonspecific edema, four with varicosities, and one patient each with acute deep vein thrombosis, chylous ascites, and excision of the greater saphenous vein for arterial bypass grafting. Five patients with obstructed patterns had previous arterial bypass procedures, one had trauma to the extremity, and one had lymphedema tarda. The one enhanced lymphoscintigraphic pattern was seen in a patient with acute cellulitis. All patients had Doppler venous examinations and other studies included strain gauge phlethysmography, venograms, computed tomography, magnetic resonance imaging, and ultrasound. As with other scintigraphic imaging agents used to study lymphatic flow, Technetium 99m provides clinically useful information in evaluating the swollen extremity noninvasively.

Adult↗