Biomedical subjects

J M Mountz

Publications and source records attributed to J M Mountz.

64 records · Page 4Linked to original sources

PubMed1988

Blood flow imaging of a posterior circulation stroke. Use of technetium Tc 99m hexamethylpropyleneamine oxime and single photon emission computed tomography.

Regional cerebellar perfusion was imaged using technetium Tc 99m hexamethylpropylene amine oxime and single photon emission computed tomography (HM-PAO-SPECT) in a patient with chronic left lateral medullary syndrome with contralateral weakness due to traumatically induced thrombosis of the left vertebral artery. Despite continued neurologic deficits, x-ray transmission computed tomography was normal. However, HM-PAO-SPECT demonstrated that blood flow to the left cerebellar hemisphere was significantly impaired. This abnormality was still apparent after correction for atrophy as estimated by magnetic resonance imaging. Technetium Tc 99m hexamethyl-propyleneamine oxime and single photon emission computed tomography effectively imaged regional blood flow in the vertebrobasilar circulation and appears to more clearly reflect the nature and extent of the neurologic deficit than either x-ray transmission computed tomography or magnetic resonance scanning.

Cerebrovascular Circulation↗

PubMed1988

SPECT imaging of moyamoya disease using 99mTc-HM-PAO. Comparison with computed tomography findings.

99mTc-HM-PAO was used to evaluate regional cerebral blood flow in a 26-year-old woman with Moyamoya disease. This patient had an 18-month history of recurrent neurologic deficits and had angiographic evidence of Moyamoya disease. She had used oral contraceptives and cigarettes, but had no other risk factors for stroke. Single photon emission computed tomographic images showed bilateral and asymmetric reductions in blood flow to anterior and lateral brain regions. These findings correlated better with clinical symptomatology and suggested more extensive brain involvement than did computed tomography.

Adult↗

PubMed1988

Silent infarction of the brain. Incidental finding demonstrated by SPECT.

Bone imaging of the body is often requested to rule out metastatic disease. A patient with suspected breast carcinoma underwent bone imaging which revealed a focal area of uptake that appeared to be localized in the right posterior calvarium. The initial interpretation was possible solitary metastatic breast carcinoma to the skull. Skull radiographs and head computed tomography (CT) were suggested for follow-up evaluation. The skull series was performed immediately after bone imaging and was negative. Further clinical information revealed that the patient recently had undergone total right internal carotid artery ligation for treatment of a large, surgically inaccessible right cavernous aneurysm. SPECT imaging of the head localized the region of abnormal uptake adjacent to the calvarium, which suggested the uptake was due to a recent brain infarction or metastatic disease to the brain. A CT scan performed 4 days later demonstrated generalized cerebral atrophy, but was otherwise normal, ruling out metastatic breast carcinoma. This case emphasizes the importance of SPECT imaging when a solitary skull lesion is found on bone imaging. SPECT can localize the lesion to be within the brain and/or skull and can aid in further investigative management. A lesion located at the periphery of the brain may be due to an occult stroke. This finding is of particular consideration in the elderly in whom there is a relatively high incidence of coexisting cancer and silent brain infarction.

Aged↗

PubMed1988

Thallium-201 tumor/cardiac ratio estimation of residual astrocytoma.

Treatment of high-grade astrocytoma includes surgery, chemotherapy, and various methods of irradiation. Radiation therapy usually results in necrosis and edema around the primary tumor site. Contrast-enhanced computerized tomography (CT) and standard radionuclide imaging techniques are unable to reliably distinguish recurrent tumor from necrosis or edema since these images depict localization of contrast material or tracer, which primarily depends on blood-brain barrier breakdown. Thallium-201 (201Tl) appears to incorporate into viable tumor cells more rapidly than into normal brain cells. This report describes a new method to quantify the uptake of 201T1 in the tumor: the tumor-to-cardiac uptake ratio (T/C). Twenty-three 201T1 brain scans were performed on eight patients to differentiate recurrent viable high-grade astrocytoma from posttherapy changes. Planar images of the head and heart were obtained in order to calculate the ratio of tumor counts to cardiac counts. This ratio represents a numerical estimation of 201T1 uptake in the brain tumor relative to cardiac counts and is expressed as the T/C index. The T/C index correlated well with the clinical course in all eight patients. In general, however, CT suggested more extensive regrowth of tumor than the actual clinical status suggested. In one patient's course of radiological monitoring, tumor recurrence was detected by means of 201T1 imaging four months prior to its appearance on CT. In conclusion, when performed serially, the T/C index can provide an accurate estimate of residual tumor burden or recurrence, and detect and quantify viable tumor during therapy.

Adult↗

PubMed1988

Scintigraphic localization of ovarian dysfunction.

To assess the potential role of scintigraphy in the evaluation of clinically and biochemically suspect ovarian hyperandrogenism (HA), dexamethasone suppression 131I-6 beta-iodomethyl-19-norcholesterol (NP-59) scans were performed to characterize ovarian function in nine patients. Pelvic ultrasound and/or computed tomography (CT) identified anatomic abnormalities in the adnexal region in six women in whom there was discernible pelvic accumulation(s) of NP-59. In the remaining three patients testosterone levels were normal or only slightly elevated and the NP-59 scan did not demonstrate abnormal adrenal or pelvic uptake. CT and/or ultrasound studies failed to demonstrate an abnormality in the pelvis suggesting excessive peripheral conversion or abnormal end organ sensitivity of androgen precursors as potential etiologies of their HA. In three women with androgen secreting lipoid tumors of the ovary, unilateral, pelvic NP-59 activity was noted; these tumors were subsequently resected. Two women with bilateral pelvic NP-59 uptake were later shown to have hyperthecosis with markedly asymmetric and enlarged ovaries. In one woman the extent of asymmetric NP-59 uptake was anticipated by the asymmetry of ovarian vein androgen levels at selective venous catheterization. In another woman with markedly asymmetric polycystic ovary disease, intense focal uptake of NP-59 localized to the side of the anatomically abnormal, enlarged ovary. Thus, our preliminary study reviews our experience to date and suggests that NP-59 scintigraphy may be used to localize both tumorous and nontumorous ovarian dysfunction in states of HA and virilization.

Adosterol↗

PubMed1986

The appearance of a large mesenteric varix on a technetium-99m red blood cell gastrointestinal bleeding study.

Detection of gastrointestinal bleeding using Tc-99m labeled RBCs has proven to be clinically useful although false-positive images associated with abnormal vascularity remain problematic. The scintigraphic appearance of a large mesenteric varix is presented, and its potential confusion with gastrointestinal bleeding is discussed. Correlative CT and angiographic images are presented.

Angiography↗

PubMedDate not supplied

Brain structure localization in positron emission tomography: comparison of magnetic resonance imaging and a stereotactic method.

A method commonly used for localization of brain regions on positron emission tomographic (PET) images is direct visualization and designation of structure on the image itself. This technique, however, is limited to portions of the brain having sufficient differential radionuclide uptake to permit the recognition of structure by observers familiar with brain anatomy. Two other methods commonly used instead of direct visualization are magnetic resonance imaging (MRI) and stereotactic methods of localization. This report compares the accuracy of a MRI method versus a stereotactic method of brain structure localization of PET. The three localization methods were analyzed for sixteen different brain regions in 5 different subjects by two independent observers. The results were converted to PET pixel size (1 pixel = .127 cm) for comparison. MRI localization differed from direct visualization by a mean and standard deviation of approximately 2 +/- 1 pixels in both the X and Y dimensions. Stereotactic localization differed from direct visualization by approximately 2 +/- 1 pixels in the X dimension and by approximately 6 +/- 2 pixels in the Y dimension. This larger variation seen with the stereotactic method may be attributed to the questionable assumption of linearity of structure location with respect to size of the inner table of the calvarium.

Adult↗

PubMedDate not supplied

Validation of a reference method for correlation of anatomic and functional brain images.

We describe a reference device that provides accurate correlations between anatomic and functional brain images. The reference device, which generates fiduciary reference points on sequential scan planes, is positioned adjacent to the orbitomeatal line of the subject, and held in place by a framework anchored to the external auditory meatus. The reference system was tested on 17 subjects undergoing Tc-99m-hexamethylpropyleneamine oxime (Tc-99m-HM-PAO) brain single photon emission computed tomography (SPECT) and cranial computed tomography (CT) scans. The centers of the caudate nuclei, thalami, brain stem, and cerebellar vermis were identified independently on CT and SPECT. The average difference +/- 1 sd between structure locations (x, y, and z) on SPECT and CT were calculated as 1.86 +/- 1.5, 2.16 +/- 1.4, and 1.83 +/- 1.9 mm, respectively. The relevance of the method to clinical applications is illustrated by the localization of a recurrent viable glioma and an epileptogenic focus. This reference system provides an accurate, rapid, and noninvasive patient-specific method for the correlation of brain structure with brain function.

Brain↗

PubMedDate not supplied

A reference system for neuroanatomical localization on functional reconstructed cerebral images.

The correlation of anatomical with functional brain images is of critical importance for data analysis. We have designed and tested a reference system method that provides accurate localization of neuroanatomy on functional brain images. The method differs from prior techniques using headholding devices in that it does not require head fixation and is noninvasive. The reference system can be quickly, accurately, and reproducibly applied to the patient's head with respect to the surface anatomy of the head. The reference system is easily adaptable to multiple imaging modalities. The reference system is implemented with the aid of a computer algorithm that reconstructs the anatomic images into a new image matching a selected functional image. Accuracy and reproducibility of placement of the reference system was demonstrated by the application of the system on multiple subjects by two independent observers. The use of this method provides accurate correlation between functional and anatomical brain images.

Brain Mapping↗

PubMedDate not supplied

MR imaging of the thyroid: comparison with scintigraphy in the normal and diseased gland.

Spin-echo magnetic resonance (MR) imaging of the thyroid gland was performed in patients using a superconducting magnet operating at 0.35 T. There were 17 women and two men with an age range of 21-77 years. All of the patients with disease were also evaluated with scintigraphy and three of the four subjects with normal thyroid glands also had scintigraphy. Final diagnoses in the patients were normal gland in four, Graves disease in two, thyroid cyst in one, benign follicular adenoma in two, papillary cell carcinoma in one, Hürthle cell carcinoma in one, Hashimoto thyroiditis in one, and multinodular goiter in seven. The normal thyroid and surrounding anatomy were clearly demonstrated by intrinsic signal intensity differences of the tissues. The thyroid gland in Graves disease was enlarged and had homogeneously increased signal intensity at all pulse sequences compared with skeletal muscle and normal thyroid. The thyroid cyst and benign adenoma were well defined; however, the cyst displayed the greater signal intensity on more T2-weighted pulse sequences. The MR signal intensity features of multinodular goiter and Hashimoto thyroiditis appear similar to those of the normal gland. In cases of focal masses, MR could not reliably distinguish benign from malignant tumor. However, using intensity ratio data there was a statistically significant difference between solid and hemorrhagic cystic disease.

Adenoma↗