Use of goniometry to predict inadequate flexion-extension roentgenograms: a preliminary study.

Background: Flexion-extension roentgenograms (FER) of the cervical spine are often inadequate because of limited range of motion (ROM). The purpose of this study was to determine the utility of goniometry to predict a patient's ability to achieve sufficient ROM to obtain adequate FER.

Methods: We evaluated 65 consecutive blunt trauma patients undergoing evaluation by FER in the emergency department.

Contrast-enhanced MR angiography for evaluation of vascular complications of the pancreatic transplant.

Vascular complications are a common cause of postoperative dysfunction in a pancreatic transplant. Coronal three-dimensional (3D) contrast material-enhanced magnetic resonance (MR) angiography performed with high spatial and temporal resolution is a safe and effective method of assessing these vascular complications. A study was performed of selected patients who had undergone MR imaging and MR angiography during the past 6 years for evaluation of graft dysfunction following pancreatic transplantation.

Use of CT angiography to classify endoleaks after endovascular repair of abdominal aortic aneurysms.

Purpose: Accurate endoleak detection and classification is critical for the follow-up of patients who have undergone endovascular aneurysm repair (EVAR). This determination is often made with computed tomography angiography (CTA). This investigation was performed to determine the accuracy of CTA in the classification of endoleaks in patients who have undergone EVAR.

Indirect detection of lung perfusion using susceptibility-based hyperpolarized gas imaging.

Purpose: To address the problem of inadequate signal-to-noise ratio (SNR) encountered in lung perfusion magnetic resonance imaging (MRI) by developing an indirect detection based on the strong hyperpolarized (HP) gas signal.

Materials And Methods: Our model is based on detecting the effects of gadolinium (Gd) flowing through lung capillaries by recording the phase of the nearby alveolar HP gas. In a HP gas 3He phantom we imaged gas phases before and after removing tubes containing paramagnetic solution away from the phantom.

Magnetic resonance angiography.

MRA and MRI have become increasingly important diagnostic modalities in vascular surgery. The ability to obtain cross-sectional and angiographic images by these noninvasive and non-nephrotoxic modalities represents one of the most significant advances in vascular surgery over the past decade. We review the current status of MRI and MRA in vascular surgical practice.

Benign and malignant lesions of the stomach: evaluation of CT criteria for differentiation.

Purpose: To determine the sensitivity and specificity of computed tomographic (CT) criteria for differentiating benign from malignant stomach lesions in patients with a thickened gastric wall at CT.

Materials And Methods: A radiology department file search revealed 36 patients with a thickened gastric wall at CT who underwent double-contrast barium suspension upper gastrointestinal tract examinations within 6 weeks before or after CT. The authors reviewed the CT images without knowledge of the final radiologic, endoscopic, or pathologic findings to determine the degree of gastric wall thickening and the symmetry, distribution, and enhancement of the thickened wall.

MR imaging for the detection of endoleaks in recipients of abdominal aortic stent-grafts with low magnetic susceptibility.

Rationale And Objectives: This study was performed to assess the efficacy of magnetic resonance (MR) imaging for the detection of endoleaks in recipients of abdominal aortic stent-grafts with low magnetic susceptibility.

Materials And Methods: A retrospective search was conducted in radiology department records for cases of patients with low-susceptibility stent-grafts who had been evaluated with MR imaging and either computed tomography (CT) or conventional angiography within a 1-month time frame. Any endoleaks previously confirmed and classified with the use of CT and/or conventional angiography were compared with findings from MR imaging.

Utility of flexion and extension radiographs of the cervical spine in the acute evaluation of blunt trauma.

Background: The purpose of this study is to investigate the usefulness of flexion and extension radiographs of the cervical spine for the acute evaluation of ligamentous injury in cases of awake blunt trauma.

Methods: A review of 106 consecutive cases of blunt trauma evaluated with flexion and extension radiographs of the cervical spine obtained in the acute setting at a Level I trauma center was performed. The data compiled included the age, sex, mechanism of injury, type of radiographic evaluations, interpretation of all radiographic studies, and clinical outcome on follow-up.

In vivo sodium MR imaging of the intervertebral disk at 4 T.

Rationale And Objectives: The authors performed this study to evaluate whether a semiquantitative method of in vivo sodium imaging of the human intervertebral disk could provide diagnostic quality images in a reasonable time.

Materials And Methods: In vivo sodium imaging of the human spine was performed with a 4-T whole-body magnetic resonance (MR) unit by using custom-built hardware and software. Short-echo-time images were obtained with a modified three-dimensional gradient-echo sequence, a custom-built surface coil, and receiver modifications to allow for nonproton data acquisition.

Subacute clot mimicking flow in a thrombosed arterial bypass graft on two-dimensional time-of-flight and three-dimensional contrast-enhanced MRA.

Subacute intravascular thrombus can contain methemoglobin, which results in very short spin-lattice (T1) relaxation times. We describe a case of a 78-year-old man with increasing right lower extremity claudication. The patient had a thrombosed arterial bypass graft showing high signal intensity that mimicked flow on both two-dimensional time-of-flight and three-dimensional contrast-enhanced MR angiography.

Congenital esophageal stenosis in adults.

Objective: Congenital esophageal stenosis is thought to be a rare disease confined to infancy and childhood with only a few case reports in adults described.

Methods: We report five patients between the ages of 19 and 46 yr who presented with this disorder over a 2-yr period.

Results: Patients had been labeled with reflux strictures, webs, or as idiopathic in the past.

Quantitative magnetic resonance imaging demonstrates alterations of the lingual musculature in obstructive sleep apnea.

Upper airway musculature is important in the pathogenesis of obstructive sleep apnea. Electromyographic studies of patients with obstructive sleep apnea demonstrate increased activity of upper airway dilator muscles. Biopsy studies of these muscles show both adaptation and muscle injury.

Sodium NMR evaluation of articular cartilage degradation.

One of the first effects of degenerative osteoarthritis is the loss of proteoglycans from the matrix of articular cartilage. Using a model of osteoarthritic change where the cartilage has been enzymatically degraded with trypsin, the sodium NMR characteristics of the cartilage were determined as a function of changes in the proteoglycan content. The results demonstrate that the single quantum sodium signal decreases as the proteoglycan content of the cartilage matrix decreases.

Generalized reciprocity.

The remarkable theorem of reciprocity as described by D. I. Hoult and R.

Sodium MRI of human articular cartilage in vivo.

Preliminary results from in vivo sodium MRI of human patellar articular cartilage are presented. Sodium images generated of an in vitro bovine patella clearly distinguish the region of proteoglycan depletion from the region of healthy cartilage. This provides the first evidence that sodium imaging may be used to detect changes due to osteoarthritis in vivo.

Improved resolution and signal-to-noise ratio in MRI via enhanced signal digitization.

The high frequency k-space data in magnetic resonance imaging is often poorly reproduced due to the finite dynamic range of an analog-to-digital converter. The magnitude of this digitization error can equal and even exceed the magnitude of the thermal noise. Under such conditions, attempts to increase image signal-to-noise ratio via signal averaging meet with diminishing success.

Quantification of cerebral ventricular volume in English bulldogs.

Quantitative measurement of cerebral ventricle volume of eight English bulldogs was performed using magnetic resonance (MR) imaging. The mean ventricular volume was 14.8 ml.

High resolution, short echo time sodium imaging of articular cartilage.

The sodium present in articular cartilage interacts with the negatively charged proteoglycan aggregates in the matrix of the cartilage. Sodium images of short echo time may be useful for detecting changes that occur in the proteoglycan content of the cartilage. Such changes are indicative of early osteoarthritic damage, for example.

Triple quantum sodium imaging of articular cartilage.

Triple quantum (TQ) sodium imaging of bovine articular cartilage is presented. True triple quantum imaging sequence was modified to incorporate asymmetric echo acquisition. Triple quantum signal expression in the presence of residual quadrupolar interaction is presented.

Volumetric measurement of human calf muscle from magnetic resonance imaging.

Muscle mass is a determining factor in skeletal muscle function and is affected by inactivity, immobilization, disease, and aging. The aim of this study was to develop an objective and time-efficient method to quantify the volume and cross-sectional area of human calf muscles using three-dimensional magnetic resonance images. We have estimated the errors incurred in muscle volume measurements arising from artifacts known to occur in magnetic resonance imaging (MRI).

Multicoil array for high resolution imaging of the breast.

An RF multicoil array for high resolution imaging of the breast is presented. The RF multicoil is incorporated into a dedicated breast imaging apparatus that holds either breast in gentle compression during imaging. Simulations and imaging experiments demonstrate the high sensitivity and RF homogeneity of the multicoil array.

Antiphospholipid syndrome: patterns of life-threatening and severe recurrent vascular complications.

Purpose: To demonstrate the variety and recurrence patterns of severe arterial and venous thromboembolic events that occur in patients with the antiphospholipid syndrome.

Materials And Methods: Radiology records were reviewed in 800 of 1,633 patients with positive test results of antiphospholipid syndrome. Patients with radiologic evidence of antiphospholipid syndrome and no other hypercoagulable state were included if the observed thromboembolic event met one or more of four criteria for severity: extreme complications or mortality, three or more recurrent events, unusually young age, and/or unusual sites affected.

Quantitative magnetic resonance imaging of upper airways musculature in an animal model of sleep apnea.

Electromyographic studies of patients with sleep apnea and of the English bulldog, an animal model of sleep apnea, indicate that there is increase activity of the airways dilator muscles. The muscles, when biopsied, show both adaptation and muscle injury. In this study we have utilized quantitative magnetic resonance imaging to characterize changes in the upper airway musculature of the bulldog in vivo.

17O-decoupled 1H detection using a double-tuned coil.

17O-decoupled proton MR spectroscopy imaging with a double-tuned radiofrequency (RF) coil at 2 T was used to detect and quantify H2 17O in tissue containing various concentrations of 17O-enriched water in 5% gelatin. The pulse sequence used in these experiments consisted of a conventional proton spin-echo sequence with RF irradiation at the 17O resonance frequency applied between the proton 90 degrees pulse and the signal acquisition window. The double-tuned coil provided several advantages over systems using separate RF coils for 17O decoupling and proton excitation/detection, including ensuring that the same (or similar) sample volumes are excited and decoupled and permitting accurate calibration of the 17O decoupling pulse amplitude.

Renal perfusion in humans: MR imaging with spin tagging of arterial water.

The authors tested a noninvasive technique for magnetic resonance imaging of perfusion in human kidneys. Magnetic labeling (spin tagging) of aortic arterial water was performed to generate an endogenous tracer. Breath-hold renal perfusion images obtained in seven volunteers yielded average perfusion rates in cortex and medulla of 278 mL.