Spiral spin-echo magnetic resonance imaging of the pelvis with spectrally and spatially selective radiofrequency excitation: comparison with fat-saturated fast spin-echo imaging.

OBJECTIVE: The authors describe their initial clinical experience in comparing a spiral spin-echo technique with a fat-saturated fast spin-echo technique for imaging the pelvis. METHODS: A total of 18 patients were imaged with both spiral spin-echo and fat-saturated fast spin-echo magnetic resonance imaging. The spiral spin-echo technique combines a spectrally and spatially selective radiofrequency excitation with a spiral k-space trajectory. This technique permits rapid acquisition of T2-weighted water-only images. RESULTS: The spiral spin-echo images were judged superior to the fat-saturated fast spin-echo images in terms of uniformity of fat suppression and absence of flow-related artifacts. However, the overall image quality of the spiral spin-echo images was inferior to that of the fat-saturated fast spin-echo images, as a result of blurring caused by off resonance effects. The two techniques were judged equivalent in terms of conspicuity of the abnormality and diagnostic information. CONCLUSION: The authors conclude that the spiral spin-echo technique holds promise, particularly if combined with a deblurring algorithm.

Degenerated uterine leiomyoma mimicking acute appendicitis: sonographic diagnosis.

The present study reviews four cases in which degenerated uterine leiomyomas mimicked appendicitis clinically. The correct diagnosis was made prospectively by sonography in each case. Appendicitis was excluded by graded compression sonography and an exophytic uterine leiomyoma was identified at the point of maximal symptoms. The leiomyomas demonstrated central hypoechoic foci, but no detectable Doppler flow indicating necrosis. Although the phenomenon of a degenerated uterine leiomyoma mimicking appendicitis clinically is known, sonographic diagnosis has not been reported previously. The importance of making this diagnosis sonographically is that management of a degenerated leiomyoma is conservative and unnecessary surgery could be avoided.

Sonography of appendicitis and diverticulitis.

Graded compression sonography has gained widespread acceptance as a useful technique to evaluate patients with atypical signs and symptoms of appendicitis. When positive, early surgery can be performed prior to perforation. When there is no sonographic evidence of appendicitis, other alternative diagnoses may be established. CT scans and the contrast enema remain the primary imaging modalities to evaluate suspected diverticulitis; however, sonography may be useful in selected patients with an atypical clinical presentation.

Dupuytren's contracture: MR imaging findings and correlation between MR signal intensity and cellularity of lesions.

OBJECTIVE: Dupuytren's contracture is a common fibrosing disorder of the hand which often results in progressive and debilitating flexion contractures of the fingers. Recurrence after surgical release is common and may be related, in part, to the cellularity of the lesion. We describe the MR appearance of Dupuytren's contracture and correlate signal characteristics with the degree of cellularity of the lesion. SUBJECTS AND METHODS: A total of 11 hands in 10 patients were studied. All patients had surgical resection after MR imaging (median interval, 3 days). The surgical and pathologic findings were correlated with the MR findings. The signal characteristics of the lesions were correlated with the histologic findings. RESULTS: We found that MR imaging was accurate for detecting Dupuytren's contracture and depicting its extent. The lesions include subcutaneous nodules, usually at the level of the distal palmar crease, and cords that lie parallel and superficial to the flexor tendons. The cords had a uniformly low signal intensity (similar to the signal intensity of tendon) on both T1- and T2-weighted images in 18 of 22 cases, whereas the remaining four cases had a low to intermediate signal intensity on T1-weighted images (a slightly higher signal intensity than that of tendon) and a low signal intensity on T2-weighted images. Histologically, the cords were hypocellular and composed of dense collagen. Most nodules had an intermediate signal intensity (similar to that of muscle) on both T1- and T2-weighted images (10 of 13 cases), usually stippled with focal areas of lower signal intensity. Histologically, these nodules were mostly cellular. Three of the nodules had a low signal intensity on both T1- and T2-weighted images and were hypocellular histologically. CONCLUSION: We conclude that MR imaging can be used to define palmar involvement in Dupuytren's contracture. The signal characteristics of the lesions correlate with the degree of cellularity of the lesions as seen histologically. The ability to assess preoperatively the cellularity of lesions of Dupuytren's contractures may be of prognostic significance, because highly cellular lesions tend to have higher rates of recurrence after surgery than do hypocellular lesions.

In vitro proton spectroscopy of normal and abnormal prostate.

Previous biochemical and 13C NMR spectroscopic data have suggested that the metabolism of citrate, a secretory product of normal prostate, may be interrupted in prostate cancer. In the present study in vitro 1H NMR spectroscopy was used to see if cell strains derived from prostate cancers could be reliably distinguished from those of normal prostate epithelium. High-resolution one-dimensional and two-dimensional J-resolved 1H NMR spectra as well as gas chromatography coupled with mass spectroscopy were used to study extracts of highly defined cell strains from normal peripheral zone, normal central zone, adenocarcinoma, and benign prostatic hyperplasia. Resonances assigned to citric acid and related metabolites were identified. Cell strains derived from prostate cancers tended to have smaller amounts of citrate than those from normal prostate epithelium. However, the differences were small and not statistically significant. The lack of statistically significant differences may reflect the variability present in both normal and abnormal cell strains and thus underscore the well-known difficulty in differentiating normal and cancerous tissues.

Metabolic adjustments of small passerine birds for migration and cold.

Passerines (members of the order Passeriformes such as finches, chickadees, jays, and warblers) are predominantly small birds characterized by relatively intense metabolic rates. Members of this group breeding at middle or high latitudes may either evade winter cold by migration or enhance their resistance to it by acclimatization. We review the energetic consequences associated with these two modes of response. Despite their apparent dissimilarity, migration and winter acclimatization both depend on substantial aerobic endurance, and both involve extensive power outputs by the flight muscles in locomotion or shivering. Such power outputs entail extensive deposition and catabolism of fat. Information available on these processes and their control in passerine birds is discussed. Knowledge of them is still in a formative stage, but it is already clear that aerobic capacity of passerines is stable at a high level throughout the year. However, changes are observed in the activity of certain enzymes involved in the catabolism of fats and carbohydrates. Full interpretation of these findings must await additional research. Nevertheless it is evident that the complex processes of migration and winter acclimatization are intimately linked with the metabolic properties of the highly aerobic skeletal muscle contained within the flight apparatus of passerines.

Seasonal acclimatization in American goldfinches: the role of the pectoralis muscle.

The present study attempts to assess whether the marked seasonal changes in the capacity for shivering thermogenesis in American goldfinches (Carduelis tristis) involve adjustments of metabolic pathways of the pectoralis muscles similar to those observed in mammalian muscle in response to endurance training, i.e., changes favoring increased reliance on fatty acid oxidation and decreased utilization of carbohydrate reserves. Analysis of seasonal changes in enzyme profile of the pectoralis muscle revealed that winter-acclimatized birds have significantly greater (P less than 0.05) activities of phosphorylase, phosphofructokinase, and beta-hydroxy-acyl-CoA dehydrogenase than do birds in other seasons. The activities of citrate synthase and hexokinase do not vary seasonally. These results differ fundamentally from the pattern of changes in enzyme activities associated with endurance adaptation in mammals. Furthermore no seasonal changes were observed in capacities for the oxidation of fatty acids (palmitate and linoleate) or pyruvate in either crude homogenates or isolated mitochondria of goldfinch pectoralis muscles. The oxidation of pyruvate by isolated pectoralis muscle mitochondria was inhibited (greater than 90%) by the oxidation of palmitoyl carnitine at palmitoyl carnitine concentrations as low as 50 microM. These data agree with physiological observations indicating little use of glucose by this tissue during steady-state shivering. However, the extent of this inhibition does not vary seasonally. Therefore the present study fails to document any significant seasonal change in the catabolic pathways of the pectoralis muscle that would link observed seasonal changes in capacity for shivering thermogenesis with a shift in the balance of substrate use by this tissue.

Muscle enzyme profile, diet, and flight in South American bats.

Activities of four catabolic enzymes (citrate synthase, hexokinase, 3-hydroxyacyl-CoA dehydrogenase, and phosphorylase) were measured in the pectoralis muscles of 10 species of South American bats, representing four families. The pattern of enzyme activities in these tissues suggests that these muscles differ qualitatively with other mammalian and avian muscles in two respects. First, the muscles of all 10 bat species were much more highly oriented toward fat metabolism and away from glucose metabolism than in any previously measured skeletal muscle. Second, the species were divided into two major groups with respect to hexokinase activity. Primarily frugivorous species had hexokinase activities about 2-3 times as high as insectivorous species. It is suggested that the weight restrictions of flight limit glycogen storage and thus bias muscle metabolism toward fat. However, the extent to which pectoralis muscles have the capacity for glucose oxidation appears to be dependent on the intake of dietary glucose.

Changes in mitochondrial components of hamster brown adipose tissue in response to cold acclimation.

Cold acclimation of hamsters was found to result in an increase in cytochrome concentration relative to ATPase activity in brown adipose tissue mitochondria, but not in liver mitochondria. These data lend support to the hypothesis that the uncoupled respiration characteristic of non-shivering thermogenesis is the result of an adaptive change in the composition of brown adipose tissue mitochondria in response to cold acclimation.