Glomus tympanicum chemodectomas: radiographic and clinical characteristics

Glomus tympanicum chemodectomas are benign neoplasms that develop from normal glomus bodies located along the Jacobson (tympanic) nerve in the middle ear. The medical charts and radiographic studies of 55 patients with these tumors were reviewed. Women outnumbered men in a ratio of 3.5:1, and the patients' average age when they initially reported symptoms was 52 years. Tinnitus, ear pulsations, and diminished hearing were the most frequent symptoms. No patient had a second chemodectoma, and none of seven patients who were tested had elevated neuroendocrine compounds. Review of the radiographic examinations showed that direct coronal, thin-section computed tomography (CT) was the most sensitive means of demonstrating glomus tympanicum chemodectomas. Magnification angiography was also a sensitive diagnostic study, typically depicting a trapezoidal, hypervascular, middle-ear mass that appeared initially in the middle-to-late arterial phase and quickly disappeared in the venous phase. Differentiation from an aberrant internal carotid artery is critical to prevent arterial biopsy.     

Decreased energy demanding processes in the frontal lobes of schizophrenics due to neuroleptics? A P-magneto-resonance spectroscopic study

In the present investigation on ³¹P-magneto-resonance spectroscopic parameters in the frontal lobe, we found phosphocreatine levels and the ratio phosphocreatine/adenosine triphosphate to be increased (12.62±1.98% resp. 0.31±0.06) in 50 neuroleptic-treated schizophrenics, whereas no differences were detected in 10 neuroleptic-free patients (11.66±2.57% resp. 0.29±0.08) compared to 36 controls (11.37±1.45 resp. 0.29±0.04). This result points to a major role of neuroleptics in the metabolism of high-energy phosphates.     

Pheochromocytoma and the normal adrenal medulla: improved visualization with I-123 MIBG scintigraphy

The radiopharmaceutical iodine 131 metaiodobenzylguanidine (I-131 MIBG) has been shown to locate pheochromocytomas scintigraphically with a false-negative rate of approximately 13%. To improve image quality and reduce the false-negative rate, I-123 was examined as a radioactive label for MIBG, as it has many advantages over I-131, including superior dosimetry and better detection efficiency. Diagnostic doses of 0.5 mCi (18.5 MBq) I-131 MIBG and 10.0 mCi (370.0 MBq) I-123 MIBG with nearly equivalent radiation dosimetries were compared in 18 patients with known or suspected pheochromocytomas. Images of superior quality were obtained with I-123 MIBG in 18 of 18 patients, and in eight cases lesions not visualized on I-131 MIBG scintigraphy were portrayed. A further advantage of I-123 MIBG is that it permits single photon emission computed tomography (SPECT). This was performed in six cases and provided additional information in three cases. The adrenal medullae were definitely visualized using I-123 scintigraphy in eight of 14 patients still possessing adrenal glands, whereas I-131 MIBG images portrayed the adrenal medulla in only one of 14 cases. Five remaining patients had multiple abdominal tumor deposits that were difficult to differentiate from normal adrenal medullae.     

Application of image-guided surface coil P-31 MR spectroscopy to human liver, heart, and kidney

Localized phosphorus-31 magnetic resonance (MR) spectroscopy in humans has previously been accomplished with surface coils by means of depth-resolved surface coil spectroscopy or rotating frame experiments, in which the extent of tissue sampled critically depends on surface coil placement. The authors' goal was to modify the surface coil image-selected in vivo spectroscopy (ISIS) experiment to accomplish three-dimensional volume selection through application of selective pulses in the presence of B0 gradients. Advantages of ISIS include the ability to use proton images to define the volume of interest (VOI) and reduced dependence on exact positioning of the surface coil. However, rapid replication of the surface coil ISIS experiment can cause spectral contamination from signals originating outside the VOI. A modified version of the ISIS experiment was developed to alleviate contamination under conditions of rapid replication. Applications of localized P-31 MR spectroscopy for observation of high-energy phosphorus metabolites are presented in human liver, heart, and transplanted and normal kidney.     

Clinical experiences with a new total wrist prosthesis

Summary For many individuals the preservation of wrist motion is essential for augmentation of fine motor control of the hand and fingers. When significant functional disability exists at the wrist, currently available surgical treatment includes soft tissue arthroplasty, carpectomy, or arthrodesis. A total wrist joint has recently been developed which offers the patient the potential of a pain-free, stable, and mobile wrist. Based upon the principles of total joint replacement as applied to the hip and knee, the prosthesis is secured to the carpus and radius with methylmethacrylate cement following removal of the navicular, lunate, and head of the capitate. The configuration of the prosthesis interface provides for the two planes of motion normally seen at the wrist; 90° of flexion and extension and 50° of radial ulnar deviation are permitted by the design. Candidates for total wrist replacement are patients who exhibit far advanced disease at the wrist and who might be considered for arthrodesis, but in whom the permanent loss of motion would represent a significant handicap. To date, 20 prostheses have been inserted in 17 patients. The longest follow-up is 14 months. All but 2 patients have gained a useful range of motion. All patients have noted dramatic relief of pain and deformity, permitting them to perform tasks which were preoperatively impossible.

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Zusammenfassung Für viele Betroffenen ist die Erhaltung der Handgelenksbeweglichkeit wichtig für die Verstärkung der feinen Muskelkontrolle von Hand und Fingern. Beim Bestehen von erheblichen funktionellen Einschränkungen des Handgelenkes besteht die chirurgische Behandlung gegenwärtig in Fascieninterpositionsplastiken, Carpektomie oder Arthrodese. Eine Handgelenksendoprothese wurde kürzlich entwickelt, die dem Patienten die Möglichkeit eines schmerzfreien, stabilen und beweglichen Handgelenkes bietet. Entsprechend den Prinzipien des totalen Gelenkersatzes für Knie und Hüfte wird diese Prothese am Carpus und Radius mit Methylmethacrylatzement fixiert, nach Entfernung des Os naviculare, Os lunatum und Kopf des Os capitatum. Die Form der artikulierenden Gelenksflächen ermöglicht die Beweglichkeit in zwei Ebenen, die auch normalerweise am Handgelenk besteht. 90° Beugung und Streckung sowie 50° radiale und ulnare Abweichung erlaubt die Konstruktion. Geeignet für Totalersatz des Handgelenkes sind Patienten mit fortgeschrittener Erkrankung des Handgelenkes, die normalerweise für eine Arthrodese vorgesehen sind, jedoch bei denen ein dauerhafter Bewegungsverlust des Handgelenkes eine erhebliche Behinderung bedeutet. Bis heute sind 20 Prothesen in 17 Patienten eingesetzt worden. Der längste Nachuntersuchungszeitraum beträgt 14 Monate. Bis auf 2 Patienten haben alle einen brauchbaren Bewegungsumfang erreicht. Alle Patienten haben eine deutliche Erleichterung der Schmerzen und Deformität festgestellt, die ihnen ermöglicht, Arbeiten auszuführen, die präoperativ nicht möglich waren.

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The prosthesis is being manufactured by How-medica, International.     

Pulse sequence optimization for MR imaging using a paramagnetic hepatobiliary contrast agent

Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.