The purpose of the study was to describe typical MRI findings in various types of idiopathic inflammatory myopathies in adulthood and to correlate the MRI with histopathological and electromyographic findings, and the serum creatine kinase (CK) activity. A third goal was to assess the diagnostic value of the use of gadolinium-DTPA (Gd-DTPA). Fifty-eight patients (35 women, 23 men), aged 21-83 years (median age 59 years), suffering from idiopathic myositides (13 with acute and 45 chronic diseases; 25 with polymyositis, 14 with dermatomyositis, 8 with granulomatous and 11 with inclusion body myositides) were examined with MRI. Seventeen of them received an intravenous infusion of Gd-DTPA. Histopathological and MRI findings of 21 muscles of 18 patients were compared. MRI of skeletal muscles showed abnormal signal intensities in 56 (96.6%) of the 58 patients. MRI abnormalities were found more often than elevated CK activity (P < 0.001). The hyperintensity of T2-weighted images was more conspicuous than on T1-weighted images in 26 (44.8%) patients, indicating oedema-like abnormalities. MRI of 50 (86.2%) patients showed fat replacement. In acute myositides, oedema-like abnormalities were more often visible and in muscle lipomatosis less often visible than in chronic diseases (P < 0.05 each). In dermatomyositis oedema-like abnormalities were more and lipomatosis less frequent than in the other types of myositis (P < 0.005) and correlated with the acuteness of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

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This study compares sonographical, histopathological, magnetic resonance imaging (MRI), and electromyographical (EMG) findings following acute muscle denervation. We performed an experimental denervation of the supraspinatus and infraspinatus muscles on 35 New Zealand white rabbits by segment resection of the suprascapular nerve. The sonographical appearance of the supraspinatus muscle was followed and documented at short time intervals within a 2-month follow-up period. The sonographical, histopathological, and MRI changes due to denervation suggest a regular pattern. Apart from the reduction of the muscle diameter, there were considerable sonographical signs of denervation with an increase of echointensity and inhomogenicity of echotexture that appeared on day 14 after injury, and progressed continuously with time. MRI revealed a remarkable increase in signal intensity 3 weeks after denervation and reproducible T2 times. Pathological spontaneous activity on EMG could also be detected from day 14 after injury. Conventional histopathological staining methods (H&E, NADH, ATPase, basic and acid phosphatase) confirmed denervation and absence of reinnervation. The first nonspecific histopathological changes were seen 11 days after denervation in the form of moderately atrophic fibers. Typical histopathological signs of denervation appeared 3 weeks after nerve dissection. In summary, EMG, ultrasound, MRI, and histopathology each showed first abnormalities after about 2 weeks. In addition to EMG, sonography and MRI can document the course of muscle atrophy and mesenchymal abnormalities in neurogenic muscle lesions.

Wave mixing is an archetypical phenomenon in bosonic systems. In optomechanics, the bidirectional conversion between electromagnetic waves or photons at optical frequencies and elastic waves or phonons at radio frequencies is building on precisely this fundamental principle. Surface acoustic waves (SAWs) provide a versatile interconnect on a chip and thus enable the optomechanical control of remote systems. Here we report on the coherent nonlinear three-wave mixing between the coherent fields of two radio frequency SAWs and optical laser photons via the dipole transition of a single quantum dot exciton. In the resolved sideband regime, we demonstrate fundamental acoustic analogues of sum and difference frequency generation between the two SAWs and employ phase matching to deterministically enhance or suppress individual sidebands. This transfer between the acoustic and optical domains is described by theory that fully takes into account direct and virtual multiphonon processes. Finally, we show that the precision of the wave mixing is limited by the frequency accuracy of modern radio frequency electronics.

After sonographical examination with a 7.5-MHz linear array scanner, we created an experimental muscle injury of known site and location on 28 New Zealand white rabbits by stabbing them with a scalpel in the supraspinatus muscle. The changes in the healing process were followed and documented by sonography and magnetic resonance imaging (MRI) before and 2, 5, 11, 14, 36 and 64 days after injury. The changes in sonography and MRI followed a regular course. Ultrasound revealed an echo-poor area after injury with ever increasing echogenicity from the 14th day. Strong reflexes were found after 2 months. MRI showed few changes, only a slight increase of signal intensity, but a characteristic curve of calculated T2-times (a program of the MRI software). The interpretation of the sonographical picture in histopathological terms remained limited. The development of a hematoma and of fibrous scars can be followed up by sonography, but it is not possible to determine the point of time after injury very accurately. Nevertheless, sonography is a method of great value in the diagnosis of muscle injuries and, given certain limits, in the follow-up of the healing process, too. The significance of MRI can be increased by calculations with the implemented software, as in our study calculated T2-times produced a characteristic curve reflecting the shift of fluids after muscle injury.