Diagnosis of osteoid osteoma using computed tomography

Osteoid osteoma is a benign lesion of bone generally diagnosed using conventional radiography or conventional tomography. Computed tomography can be used in difficult cases to localize a clinically suspected lesion. In this report we present two patients in whom an osteoid osteoma was detected using computed tomographic scanning; in an additional patient computed tomography failed to localize a lesion, probably because the slice thickness was too great. Because the nidus of the lesion is small--generally several millimeters in diameter--accurate CT localization requires that narrowly collimated, closely spaced sections be obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24977/1/0000404.pd

Monoclonal antibodies labeled with polymeric paramagnetic ion chelates

Polymeric paramagnetic ion chelate molecules were synthesized and covalently linked to monoclonal antibodies. The labeled antibodies retained their antigen binding capacity in vitro while carrying up to an average of 50 paramagnetic ion chelates, enabling specifically bound antibody concentrations less than 2.0 Μ M to significantly reduce proton longitudinal relaxation times. © 1986 Academic Press, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38480/1/1910030220_ftp.pd

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No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50314/1/410190427_ftp.pd

Identification of brain lesions in neuropsychiatric systemic lupus erythematosus by magnetic resonance scanning

Cranial magnetic resonance imaging in 28 systemic lupus erythematosus patients who had experienced 30 acute neuropsychiatric events showed focal brain lesions in 16 of 30 events (53%) and low brain volume (atrophy) in 20 of 30 events (67%). Definite focal lesions were significantly more frequent in patients with clinically localized neurologic deficits (8 of 8, 100%), or seizures (5 of 6, 83%) than in patients without such localizing signs (3 of 16, 19%). Many of these lesions were occult on intravenous contrast-enhanced x-ray computed tomography. In 2 patients, lesions in gray matter resolved within 2 or 3 weeks, in association with clinical improvement. Magnetic resonance imaging is an important technique for detecting the extent of brain injury in cerebral lupus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37779/1/1780310202_ftp.pd

Comparison of Dynamic Phase Enhancement of Hepatocellular Carcinoma using Gadoxetate Disodium versus Gadobenate Dimeglumine

Objective: To determine the differences in enhancement of hepatocellular carcinoma during the first 5 minutes of postcontrast phases with gadoxetic acid (Gd-EOB-DTPA) vs gadobenate dimeglumine. Methods: Ninety-five cirrhotic patients with hepatocellular carcinoma were examined on a 1.5-T scanner: 74 patients with Gd-BOPTA and 21 patients with Gd-EOB-DTPA. Same magnetic resonance imaging parameters were used for both groups. Gadoxetate isodium was administered at a dose of 0.025 mmol/kg; and Gd-BOPTA, at a dose of 0.1 mmol/kg. Results: Mean contrast-to-noise ratios (CNR) were similar in arterial (P = 0.3), portal venous (P = 0.1), and 5-minute delayed phases (P = 0.73). The CNRs of lesions in the Gd-EOB-DTPA group were lower in arterial phase, although this did not reach statistical significance. The CNRs of Gd-EOB-DTPA during the equilibrium phase was higher (P = 0.006). Conclusions: Gadoxetate isodium resulted in lower CNR during the arterial phase and higher CNR during the portal venous, equilibrium, and 5-minute delayed phases compared with gadobenate dimeglumine using the Food and Drug Administration–approved doses; however, overall, there was no statistical significance (P = 0.077)

Visualization of myocardial infarction and subsequent coronary reperfusion with MRI using a dog model

Twelve anesthetized mongrel dogs underwent left thoracotomy with placement of a removable ligature around the left circumflex coronary artery. Following a 3 to 6 hour delay, ECG-gated spin-echo MRI was performed. The ligature was then removed reperfusing the heart, and after a 10-15 min period, MRI repeated. Finally, post-sacrifice images were obtained, and the hearts chemically stained for infarct evaluation. The MR images were subjectively and quantitatively evaluated for visibility of the endocardial border and of the injured myocardium, and for changes after reperfusion. The injured tissue was variably visible in vivo, the major limitation a result of motion blurring and artifact. The abnormal tissue was easily visible on MRI in 11 animals, and not clearly visible in one. The endocardial border was easily seen in 10 animals. The variation of calculated relaxation times was high for both normal and ischemic/infarcted myocardium in the beating hearts (normal: T1 = 566 +/- 288, T2 = 38 +/- 6; injured myocardium: T1 = 637 +/- 250, T2 = 41 +/- 12) in contrast, relatively stationary skeletal muscle measured in the same images had narrower ranges (T1 = 532 +/- 199, T2 = 28 +/- 2). Changes with reperfusion were seen, but not reliably. The infarcted or ischemic zones were easily visible on post-sacrifice images in all animals imaged. Post-sacrifice relaxation times were T1 = 564 +/- 69 msec, T2 = 39 +/- 3 msec for normal heart muscle, and 725 +/- 114, T2 = 47 +/- 5 for ischemic/infarcted tissue. We conclude that acute myocardial infarction can usually be detected by MRI, given a prior knowledge of its location. However, the technique is at present likely to be of only limited value clinically in the prospective diagnosis of acute myocardial infarction, though this may improve as technology advances. Finally, signal changes following reperfusion may be visible in some cases, but not reliably so.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26951/1/0000517.pd

MR of an adrenal pseudocyst

We describe the appearance of an adrenal pseudocyst on MRI and CT. The MR characteristics of the lesion were noteworthy in that the lesion had two components with different imaging characteristics. The larger component was of low signal intensity on both T1- and T2-weighted images and might have been confused with an adrenal adenoma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30365/1/0000767.pd

Serial nuclear magnetic resonance imaging in acute myocardial infarction

Recent studies show that proton nuclear magnetic resonance (NMR) imaging can detect myocardial ischemia and acute myocardial infarction (AMI) in animal models1-3 and in humans.4-6 The area of AMI appears as increased signal intensity on the spin-echo NMR images and most likely reflects the regional edema associated with tissue necrosis.1 Thus, the time course of regional edema and the evolution of infarct healing may be revealed by serial NMR studies. In a recent canine study, Pflugfelder et al7 examined the time course of the increased NMR signal intensity associated with AMI. They found that the relative signal intensity increased between the day of AMI and 2 weeks after AMI and subsequently decreased by the 20th day. We examined the early time course of NMR changes in humans.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26729/1/0000279.pd

Metabolic effects of adenosine on regional myocardial ischemia by phosphorus 31 nuclear magnetic resonance spectroscopy

The metabolic effects of adenosine on regionally ischemic myocardium were investigated in an open-chest rabbit model by means of phosphorus 31 nuclear magnetic resonance (NMR) spectroscopy. Sixteen anesthetized New Zealand white rabbits were subjected to thoracotomy; a reversible snare occluder was placed around a large branch of the left circumflex coronary artery, and an NMR surface coil was positioned adjacent to the myocardium perfused by this vessel. The animals were placed in a 2.0 T CSI spectrometer (GE Medical Systems, Fremont, Calif.), and baseline spectra were acquired. Eight animals were treated with intravenous adenosine (25 mg/kg), and eight rabbits served as control subjects. All animals were subjected to a 10-minute period of ischemia followed by a period of reperfusion. NMR spectra were acquired during both intervals. During the occlusion period, expected increases in inorganic phosphate levels and decreases in phosphocreatine levels were observed in both groups; however, inorganic phosphate increased less in adenosine-treated animals (adenosine: 33 +/- 2.8% total spectral area during occlusion vs control: 41+/-3.1%) and phosphocreatine diminished less with adenosine (adenosine: 26+/-3% vs control: 13+/-1.2%; p<0.002). No significant differences were seen in [beta]-adenosine triphosphate levels. In both groups the metabolite levels during reperfusion recovered to near baseline values, although phosphocreatine remained slightly higher in the treated group during early reperfusion. An apparent cardioprotective effect of adenosine on relative phosphocreatine and inorganic phosphate levels can be observed in intact rabbits by means of phosphorus 31 NMR spectroscopy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29773/1/0000112.pd

Detection and sizing of myocardial ischemia and infarction by nuclear magnetic resonance imaging in the canine heart

The usefulness of NMR imaging to size infarcted and hypoperfused, ischemic myocardium was assessed in 16 dogs which underwent coronary artery occlusion and reperfusion. During occlusion, technetium-99 microspheres were injected into the left atrium. Following death, the hearts were excised and underwent NMR imaging with a 0.35 tesla magnet, using multiple spin-echo pulse sequences. The epicardium of the heart was marked to indicate the level of the NMR cross-sectional tomographic image. The heart was subsequently breadloafed into 5 mm sections and the corresponding NMR cross-section was flagged for analysis. Autoradiography was performed to measure the hypoperfused, at-risk zone, and triphenyltetrazolium chloride staining was used to measure infarct size. For the flagged tomographic slice, the size of the NMR abnormality correlated well (r = 0.95), and was comparable to the actual hypoperfused, at-risk zone of the left ventricle. However, NMR estimates of infarct size correlated less well (r = 0.75) with the pathologic measure, and significantly overestimated actual infarct size (p 1 and T2 values were consistently increased (p < 0.0005) in both the hypoperfused and infarct zones, compared to normal myocardium. We conclude that NMR imaging can detect acute myocardial ischemia and infarction, but overestimates infarct size and corresponds better to the area of hypoperfused, ischemic myocardium. In this excised canine heart occlusion-reperfusion model, the NMR abnormality corresponded best to the area including both infarction and the surrounding ischemic region.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25932/1/0000495.pd