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Biomedical subjects

J Huston

Publications and source records attributed to J Huston.

At least 55 records · Page 3Linked to original sources
PubMed1995

Intracranial cysts in autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder well known for its association with intracranial aneurysms. A series of patients with ADPKD who were screened for the presence of an intracranial aneurysm were reviewed and found to include an unexpectedly high number with intracranial arachnoid cysts. Among 247 patients with ADPKD who underwent magnetic resonance imaging (180 cases) or high-resolution contrast-enhanced computerized tomography (67 cases), there were 151 women and 96 men with a mean age of 44 years. Intracranial arachnoid cysts were found in 20 patients (8.1%) with ADPKD compared to two (0.8%) in a control group without ADPKD matched for age, sex, and method of imaging (p < 0.0001). Multiple intracranial arachnoid cysts were found in two patients. Polycystic liver disease was present in 17 (85.0%) of the 20 patients with intracranial arachnoid cysts compared to 119 (52.4%) of the 227 patients without (p < 0.004). Pineal cysts were found in two patients (0.8%) and choroid plexus cysts were found in three patients (1.2%) but this was not different from the control population. None of the intracranial cysts was symptomatic and none was treated surgically. Intracranial arachnoid cysts are a relatively frequent incidental finding in patients with ADPKD, providing further support for the systemic nature of this disease. In the authors' experience with approximately 1500 patients with ADPKD, no complication has been encountered from an intracranial arachnoid cyst, suggesting that asymptomatic intracranial arachnoid cysts in patients with ADPKD require no treatment.

Adolescent↗
PubMed1995

False-positive inferior petrosal sinus sampling in the diagnosis of Cushing's disease. Report of two cases.

Inferior petrosal sinus sampling (IPSS) for adrenocorticotropic hormone (ACTH) levels in patients with Cushing's syndrome has become a useful method to distinguish ACTH-secreting pituitary tumors (Cushing's disease) from other causes of the syndrome, principally ectopic adrenocorticotropin secretion by an occult tumor. Although the test is generally regarded as highly specific, the authors recently encountered two patients whose IPSS measurements were false-positive for Cushing's disease. The results of IPSS suggested a pituitary origin of ACTH secretion in both patients, but transsphenoidal surgery failed to disclose a pituitary adenoma or to improve postoperative plasma cortisol levels. Both patients subsequently were found to have an ACTH-secreting carcinoid tumor of the lung. The false-positive IPSS studies were due to periodic hormonogenesis. The patients must be hypercortisolemic at the time IPSS is performed for the study to be valid.

Adrenocorticotropic Hormone↗
PubMed1995

Pilocytic astrocytomas: well-demarcated magnetic resonance appearance despite frequent infiltration histologically.

OBJECTIVE: To determine the magnetic resonance imaging (MRI) characteristics of pilocytic astrocytomas and to correlate them with the histopathologic findings. MATERIAL AND METHODS: MRI examinations and histopathologic findings in 56 patients with pilocytic astrocytomas were retrospectively reviewed. In 38 patients, findings on MRI were compared with those on computed tomography. RESULTS: The tumors occurred at all levels of the central nervous system, including the spinal cord. The intracranial tumors were periventricular (73%) or periaqueductal (9%). All tumors were typical pilocytic astrocytomas and were grade 1 on the basis of the World Health Organization classification. At operation, they were often circumscribed and cystic. Radiologically, the tumors were well demarcated (96%), had benign morphologic features, and almost always showed enhancement (94%). CONCLUSION: MRI of pilocytic astrocytomas typically demonstrated a relatively large, sharply demarcated periventricular mass with pronounced contrast enhancement but minimal or no associated edema. Often, the tumors were cystic on MRI. Despite the well-demarcated appearance grossly and on MRI, pathologic review showed that many of these tumors (64%) infiltrated the surrounding parenchyma, particularly the white matter.

Adolescent↗
PubMed1994

Initial clinical experience in MR imaging of the brain with a fast fluid-attenuated inversion-recovery pulse sequence.

PURPOSE: To evaluate fast fluid-attenuated inversion-recovery (FLAIR) technique for imaging brain abnormalities. MATERIALS AND METHODS: A fast FLAIR sequence was developed that provided 36 5-mm contiguous sections in 5 minutes 8 seconds. Resulting images were compared with dual-echo T2-weighted spin-echo images of 41 consecutive patients with brain abnormalities. RESULTS: Contrast and contrast-to-noise ratios (C/Ns) (for contrast between the lesion and background and between the lesion and cerebrospinal fluid) for fast FLAIR exceeded the corresponding values for T2-weighted spin-echo images for all but the second-echo lesion-to-background C/N. Fast FLAIR provided equivalent or greater overall lesion conspicuity and enabled greater lesion detection in 98% and 100%, respectively, of the evaluations. Fast FLAIR images more often had image artifact, but this did not interfere with image interpretation in a significantly (P < or = .05) greater number of evaluations. CONCLUSION: Fast FLAIR provides images that are superior to proton-density- and T2-weighted images for many image quality criteria.

Artifacts↗
PubMed1994

Blinded prospective evaluation of sensitivity of MR angiography to known intracranial aneurysms: importance of aneurysm size.

PURPOSE: To determine the sensitivity of time-of-flight and phase-contrast MR angiography for the detection of intracranial aneurysms. METHODS: Sixteen patients with 27 intracranial aneurysms previously identified with conventional angiography and 19 control patients were examined with three-dimensional time-of-flight, three-dimensional phase-contrast MR angiography, and standard MR imaging. Subvolumes of the carotid and posterior circulations, source images, and standard MR images were blindly interpreted by three experienced neuroradiologists. RESULTS: Detection of an aneurysm by a given sequence was defined as at least two of the three blinded readers identifying the aneurysm. The sensitivities of the sequences based on all 27 aneurysms were: transaxial T1, 25.9%; T2, 48.1%; PC, 44.4%; and TF, 55.6%. Two of 3 aneurysms detected with T2 but not MR angiography had adjacent blood products. Five millimeters appeared to be a critical size; the sensitivities for aneurysms greater than or equal to 5 mm were: T1, 37.5%; T2, 62.5%; PC, 75%; and TF, 87.5%. CONCLUSIONS: Three-dimensional time-of-flight MR with 512 x 256 matrix is more sensitive than three-dimensional phase-contrast or standard MR imaging for detection of aneurysms. Retrospectively, aneurysms 3 mm or larger can be identified with MR angiography; however, prospectively, 5 mm is the critical size for detection.

Adult↗
PubMed1993

Comparison of time-of-flight and phase-contrast MR neuroangiographic techniques.

Magnetic resonance (MR) angiography constitutes a group of evolving MR imaging techniques that can be used to directly image flow in arteries, veins, and cerebrospinal fluid. By using multiple MR angiographic sequences in each of 18 patients with neurologic conditions such as aneurysms, arteriovenous malformations, and carotid atherostenotic disease, the advantages, disadvantages, and unique artifacts of each technique could be investigated. Time-of-flight imaging is susceptible to saturation effects, and short T1 substances may simulate flow. Two-dimensional time-of-flight imaging is useful in cranial venography in assessing the patency of the dural sinuses or venous drainage from an arteriovenous malformation. Three-dimensional time-of-flight images depict small and medium-sized aneurysms. Phase-contrast imaging has excellent background suppression, allows variable velocity encoding, and provides directional flow information. Two-dimensional phase-contrast imaging is useful in the assessment of the patency of major vascular structures. Three-dimensional phase-contrast imaging (with 30-cm/sec velocity encoding) is also useful in depicting small and medium-sized aneurysms. Although some applications of MR angiography are clear, further study and development of the techniques are necessary to determine which imaging sequence or combination of techniques is best suited for answering specific diagnostic questions.

Adolescent↗
PubMed1993

Carotid artery: prospective blinded comparison of two-dimensional time-of-flight MR angiography with conventional angiography and duplex US.

A prospective blinded comparison of two-dimensional (2D) time-of-flight (TF) magnetic resonance (MR) angiography and color duplex flow ultrasound (US) with conventional angiography as a standard of reference was performed in 50 patients with hemispheric ischemic symptoms. The guidelines of the North American Symptomatic Carotid Endarterectomy Trial for measuring stenosis of the internal carotid artery were utilized for maximum-intensity-projection (MIP) images and conventional angiograms. While the 2D TF MIP technique overrepresented the degree of stenosis in the internal carotid arteries, it matched the performance of color duplex flow US as measured by means of receiver operating characteristic curves. A signal void on the MIP images corresponded to a 70% or greater internal carotid artery stenosis in 17 of 20 arteries. At its current state of development, the accuracy of 2D TF MR angiography equals that of US in characterizing the degree of carotid stenosis but cannot be considered a replacement for conventional angiography.

Adult↗
PubMed1993

Value of magnetic resonance angiography for the detection of intracranial aneurysms in autosomal dominant polycystic kidney disease.

The association of intracranial aneurysms with autosomal dominant polycystic kidney disease (ADPKD), the 30-day mortality rate exceeding 50% for aneurysmal rupture, the effectiveness of surgical repair of unruptured aneurysms with a low surgical risk, and the development of noninvasive imaging techniques for their detection have led physicians to consider the value of screening patients with ADPKD for unruptured intracranial aneurysms. The sensitivity and specificity of high-resolution computed tomography and magnetic resonance imaging for the diagnosis of small intracranial aneurysms have been disappointing. To determine the value of magnetic resonance angiography (MRA), 85 patients with ADPKD without symptoms related to an intracranial aneurysm and 2 patients with ADPKD presenting with a subarachnoid hemorrhage or a suspected aneurysmal leak were studied. MRA was performed with the Multisequence Vascular Package (GE Medical Systems) with use of three-dimensional time-of-flight and three-dimensional phase-contrast techniques, and postprocessing maximum intensity projection images were generated to eliminate the problem of overlapping vessels. Asymptomatic intracranial aneurysms were detected in 6 (22%) of 27 patients with and 3 (5%) of 56 patients without a family history of intracranial aneurysm or subarachnoid hemorrhage (P = 0.02, information missing in 2 patients) and in the 2 patients who presented with a symptomatic aneurysm. A stepwise logistic regression analysis indicated that a family history of intracranial aneurysm or subarachnoid hemorrhage was independently associated with the presence of intracranial aneurysms. All of the aneurysms were < or = 6.5 mm in diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Pulsatile increases in aneurysm size determined by cine phase-contrast MR angiography.

The internal flow dynamics were assessed in 16 cerebral aneurysms by cine phase-contrast magnetic resonance (MR) angiography. Six of the aneurysms were associated with subarachnoid hemorrhage and 10 were unruptured. The ruptured aneurysms demonstrated a 51% +/- 10% increase in volume between systole and diastole, while the increase in volume of the unruptured aneurysms was 17.6% +/- 8.9% (p < 0.005). The ruptured aneurysms demonstrated an approximate 1.0- to 1.5-mm increase in diameter in at least one dimension during systole. There was no relationship between aneurysm size and volumetric increases. These findings suggest that cine phase-contrast MR angiography can detect structural weakness in the aneurysmal wall. Imaging techniques that can evaluate aneurysmal wall dynamics may be useful in therapeutic planning.

Adult↗
PubMed1992

Magnetic resonance imaging of facial vascular anomalies.

In 36 patients, facial vascular anomalies were studied with 46 magnetic resonance (MR) examinations, 9 angiograms, and 5 computed tomographic scans. All lesions were categorized into classic pathologic groups on the basis of radiologic and pathologic studies, clinical examination, and behavior. Overall, 2 juvenile hemangiomas, 3 capillary malformations (port-wine stains), 18 venous malformations, 9 lymphatic malformations, and 4 arteriovenous malformations were found. MR imaging was superior to computed tomography and angiography for demonstrating the precise anatomic extent of the facial vascular anomalies and their relationship to the adjacent soft tissues but was inferior to computed tomography for demonstrating radiopaque structures such as trophic bone changes and phleboliths. MR imaging was also inferior to angiography in determining the nidus and the exact nature of collateral vascular structures in arteriovenous malformations. MR studies confirmed the clinically suspected diagnosis of facial vascular anomalies and demonstrated typical characteristics for each type of lesion. MR imaging is an ideal initial technique to triage patients with facial vascular anomalies for appropriate management, including observation, endovascular therapy, or surgical excision.

Adolescent↗
PubMed1992

Blood flow imaging through detection of temporal variations in magnetization.

Two hypotheses were tested: (a) that view-to-view variations in bulk phase and modulus of magnetization in vascular volume elements can indicate the presence of disordered blood flow, and (b) that a substantial loss of signal intensity on magnetic resonance (MR) angiograms of poststenotic regions is due to view-to-view changes in magnetization. To test these hypotheses, a technique was developed in which view-to-view variations in transverse magnetization were used to create angiographic projection images, which showed only disordered flow (disordered flow maps) in vitro and in vivo. In phantom studies, this technique recovered signal intensity downstream from stenoses. A combination of disordered flow maps with morphologic images improved visualization of stenotic regions and provided information on characteristics of local flow. These results show that view-to-view variations in transverse magnetization occur in regions of disordered flow and are an important cause of loss of signal intensity. This technique can provide information about dynamic blood flow and improve depiction of anatomic structures on MR angiograms.

Blood Circulation↗