Alterations in the supraspinatus tendon at MR imaging: correlation with histopathologic findings in cadavers

To determine the histopathologic correlates of alterations in the rotator cuff at magnetic resonance (MR) imaging, 13 cadaveric shoulders (in subjects aged 26-83 years at the time of death) underwent MR imaging in the coronal oblique plane at 1.5 T with proton-density- and T2-weighted spin-echo sequences. Areas corresponding to sites of MR imaging alterations were then examined histologically. Increased signal intensity on proton-density-weighted images (without further increased signal intensity on T2-weighted images) and an indistinct margin at the articular side of the supraspinatus tendon corresponded to eosinophilic, fibrillar, and mucoid degeneration and scarring. Areas of increased signal intensity on T2-weighted images were associated with severe degeneration and disruption of the supraspinatus tendon. Although other authors have suggested that certain MR findings are indicative of tendinitis, the histologic data in this study were not those of active inflammation but rather tendon degeneration.     

MR imaging of tuberculous arthritis: Clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.     

Rathke cleft cysts: correlation of enhanced MR and surgical findings.

PURPOSETo describe the gadolinium-enhanced MR findings of Rathke cleft cyst correlate them with the surgical findings, and define those preoperative findings that differentiate this lesion from other sellar and juxtasellar tumors.METHODSWe studied 18 patients who were diagnosed as having Rathke cleft cyst pathologically. These patients were imaged with T1- and T2-weighted coronal and sagittal spin-echo sequences. Fifteen of these patients received gadopentetate dimeglumine.RESULTSIn eight patients, the cyst showed low intensity on T1-weighted images and high intensity on T2-weighted images. At surgery, the cyst fluid was cerebrospinal fluid-like or light brown in five patients, motor oil-like in one patient, and milky in two patients. In 10 patients, cysts showed isointensity to high intensity on T1-weighted images and had various intensity on T2-weighted images. All 10 contained milky fluid. In three patients the intensity of fluid was heterogeneous. A waxy nodule was found in two patients. The position of the normal pituitary gland confirmed by surgery in all cases coincided with enhancement on MR imaging. The variable position of the normal pituitary gland was clearly identified in the sagittal images. The cyst walls showed no enhancement by gadopentetate dimeglumine.CONCLUSIONSBecause Rathke cleft cysts show variable intensities on MR, the diagnosis is often difficult when based on MR signal intensity values alone. MR imaging with gadopentetate dimeglumine does assist in the diagnosis of Rathke cleft cysts. Diagnostic clues include the lack of cyst wall enhancement and displacement of the normal pituitary gland.     

Impingement syndrome of the ankle following supination external rotation trauma: MR imaging findings with arthroscopic correlation

Our objective was to identify MR imaging findings in patients with syndesmotic soft tissue impingement of the ankle and to investigate the reliability of these imaging characteristics to predict syndesmotic soft tissue impingement syndromes of the ankle. Twenty-one ankles with chronic pain ultimately proven to have anterior soft tissue impingement syndrome were examined by MR imaging during January 1996 to June 2001. The MR imaging protocol included sagittal and coronal short tau inversion recovery (STIR), sagittal T1-weighted spin echo, axial and coronal proton-density, and T2-weighted spin-echo sequences. Nineteen ankles that underwent MR imaging during the same period of time and that had arthroscopically proven diagnosis different than impingement syndrome served as a control group. Fibrovascular scar formations distinct from the syndesmotic ligaments possibly related to syndesmotic soft tissue impingement were recorded. Arthroscopy was performed subsequently in all patients and was considered the gold standard. The statistical analysis revealed an overall frequency of scarred syndesmotic ligaments of 70% in the group with ankle impingement. Fibrovascular scar formations distinct from the syndesmotic ligaments presented with low signal intensity on T1-weighted images and remained low to intermediate in signal intensity on T2-weighted MR imaging. Compared with arthroscopy, MR imaging revealed a sensitivity of 89%, a specificity of 100%, and a diagnostic accuracy of 93% for scarred syndesmotic ligaments. The frequency of scar formation distinct from the syndesmotic ligaments in patients with impingement syndrome of the ankle was not statistically significantly higher than in the control group. In contrast to that, anterior tibial osteophytes and talar osteophytes were statistically significantly higher in the group with anterior impingement than in the control group. Conventional MR imaging was found to be insensitive for the diagnosis of syndesmotic soft tissue impingement of the ankle. Fibrovascular scar tissue distinct from syndesmotic ligaments is suggestive for the diagnosis of soft tissue impingement, but the reliability of these findings is still questionable. Electronic Publication     

MR imaging of malignant pleural mesothelioma

The magnetic resonance (MR) findings in three patients with malignant pleural mesothelioma are described. All patients had a circumferential pleural mass surrounding the lung on the affected side. These tumors had a signal of intermediate intensity on T1-weighted images. The T2-weighted images showed a slight increase in signal intensity of the mass, with focal areas of very high signal intensity due to pleural fluid. Adenopathy was demonstrated by CT and MR in two patients. The extent of the tumor and its effects on adjacent structures were well appreciated on the coronal MR images.     

腕关节的MR成像研究

目的探讨不同ＭＲ成像序列与方法在腕关节检查中的应用价值。材料与方法选取１６位健康志愿受试者的腕关节为研究对象,年龄２４～３５岁,对五种不同ＭＲ成像序列包括Ｔ。Ｗ１、ＰＤＷＩ、Ｔ２ＷＩ、ＳＴＩＲ和３Ｄ—ＧＥ及横断面、冠状面与矢状面三种成像平面进行研究。结果Ｔ１ＷＩ可以提供最佳解剖结构的细节,而Ｔ２ＷＩ可以很好地区分肿块、液体及软组织结构。ＳＴＩＲ成像有利于观察腕骨间韧带及三角纤维软骨（ＴＦＣ）结构。３Ｄ－ＧＥ成像可作连续薄层扫描,具有高信噪比、高分辨率、良好的组织对比及成像时间短等优点。横断面图像很好地显示腕管的结构;冠状面图像显示腕骨及腕骨间的相互关系、腕骨间韧带、ＴＦＣ及尺桡骨下端结构;矢状面图像可显示月骨、桡骨及头状骨间的相互关系及掌侧和背侧桡腕韧带。扫描时使用表面线圈,小ＦＯＶ,薄层可获得理想的ＭＲ图像。结论不同的ＭＲ序列及检查平面对腕关节不同组织的显示各具特异性。     

Stress fractures: MR imaging

Five cases of stress fracture were studied with high-field-strength magnetic resonance (MR) imaging. In all cases, MR images showed bandlike areas of very low signal intensity in the intramedullary space, which were continuous with the cortex. These findings corresponded in location to the sites of fracture or new bone formation noted on radiographs. Surrounding areas of decreased signal intensity in the marrow space were also consistently seen on T1-weighted images. In three cases, prominent intramedullary areas of high signal intensity were noted on T2-weighted images obtained within 3 weeks of the onset of symptoms. Juxtacortical and/or subperiosteal areas of high signal intensity were also seen on T2-weighted images in two cases. Characteristic MR findings may distinguish stress fracture from occult intraosseous fracture.     

Age-associated changes of the triangular fibrocartilage of the wrist: evaluation of the diagnostic performance of MR imaging.

To define the appearance of degenerative changes of the triangular fibrocartilage (TFC) of the wrist on magnetic resonance (MR) images, the TFCs in one wrist of each of 30 healthy subjects in three age groups (20-35, 36-50, and greater than 50 years) and six TFCs from fresh cadavers were examined by means of coronal T1-weighted spin-echo sequences. Histologic findings were compared with findings on MR images in the cadaveric TFCs. It was proved that patches or lines of signal hyperintensity within the cadaveric TFCs were caused by degenerative changes and tears. Similar changes of the TFCs on MR images of the healthy subjects may have been caused by degeneration. In the healthy subjects, degenerative changes of the TFC, usually well defined on MR images, occurred at a very early age. The TFC appears to undergo stages of degeneration comparable to those of the menisci of the knee, but differentiation between traumatic and degenerative tears may be difficult.     

MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules

BACKGROUND AND PURPOSE: Rathke's cleft cysts often may be difficult to differentiate from other intrasellar or suprasellar masses on radiologic studies. The purpose of this study was to describe the significance of intracystic nodules, a diagnostic characteristic found in Rathke's cleft cysts, on MR images. METHODS: A retrospective review of MR studies was conducted for 13 patients who, after pathologic analysis, were diagnosed as having Rathke's cleft cyst. These patients underwent unenhanced and contrast-enhanced T1- and T2-weighted axial and coronal spin-echo sequential imaging. The signal intensity and incidence of the intracystic nodules on T1- and T2-weighted images were analyzed. The signal intensity of the nodule was compared with that of white matter and surrounding cyst fluid. The signal intensity of cyst fluid was compared with the intraoperative appearance of the cyst fluid. Biochemical and pathologic analyses of the intracystic nodules were conducted in two cases. RESULTS: An intracystic nodule having high signal intensity on T1-weighted images and low signal intensity on T2-weighted images was observed in 10 (77%) of the cases. At surgery, intracystic nodules were yellow, waxy, solid masses. Pathologic analysis showed this nodule to be a mucin clump. Biochemical analysis of the intracystic nodules showed cholesterol and proteins as the main constituents. In the Rathke's cleft cyst with intracystic nodules, cyst fluid revealed low signal intensity to isointensity relative to the intensity of the nodules on T1-weighted images, and isointensity to high signal intensity on T2-weighted images. Intracystic nodules were clearly visible on T2-weighted images. CONCLUSION: Because cyst fluid of Rathke's cleft cysts shows variable intensities on MR images, the specific diagnosis is often difficult when based on MR signal intensity values alone. The presence of an intracystic nodule with characteristic signal intensities on MR images may be indicative of the diagnosis of Rathke's cleft cyst.     

Bone bruises: MR characteristics and histological correlation in the young pig

PURPOSE: To correlate magnetic resonance (MR) signal characteristics of bone bruises with histological findings. MATERIALS AND METHODS: In 14 tibiae of young pigs, bone bruises were created in the proximal tibial metaphysis. The signal intensity seen on the MR images were correlated with histological findings. The following findings were evaluated: (a) changes of signal intensity on the tibiae; (b) changes of histology on the tibiae; and (c) changes of (a) and (b) on follow-up examinations. RESULTS: We observed three types of injuries on T1-weighted images: focal or diffuse low signal, normal signal and linear low signal intensities. Severe hemorrhagic areas showed low signal intensities on all sequences of MR imaging. Fast spin-echo (FSE) T2-weighted images showed a more distinct low signal intensity than T1-weighted images. FSE short tau inversion recovery (STIR) and FSE fat saturated (FSE-FS) T2-weighted images showed similar signal intensities with FSE T2-weighted images. FS T1-weighted enhanced images showed low signal intensities with variable enhancements. Upon histological examination, hemorrhages and edemas were prominent at the subcortical areas of the contusion sites. The areas of dense, low signal intensities in all imaging sequences showed signs of severe hemorrhage. The areas of diffuse low signal and enhanced areas showed mixed areas of hemorrhages and edemas. Follow-up MR imaging showed evolution of the processes of hemorrhages and edemas with fatty marrow changes. CONCLUSIONS: MR imaging can depict changes in the bone marrow resulting from direct injury to the bone. MR imaging is a useful tool for evaluating the evolution of bone bruises.     

Knees of trained long-distance runners: MR imaging before and after competition

A previous report indicated that recreational runners had increased meniscal signal intensity and visible joint effusions on magnetic resonance (MR) images after jogging. Therefore, the knees of trained long-distance runners were evaluated by means of MR imaging before and after competition to determine the presence of any structural alterations, particularly changes in intrameniscal signal intensity and/or joint effusions. T1-weighted coronal, proton-density and T2-weighted sagittal, and short T1 inversion recovery sagittal images were obtained in five trained runners 24 hours before and within 24 hours after completion of a long-distance race (distance range, 17-50 miles). Pre- and postrace images were filmed and windowed with standardized techniques. All ligaments were normal before and after the race. No alteration in meniscal signal intensity was noted for any menisci, and there was no increase in joint fluid after running. These data indicate that the knees of trained long-distance runners do not demonstrate changes similar to those found in recreational runners, suggesting that these athletes may have adapted to the stresses of their activity.     

Magnetic resonance imaging of lateral epicondylitis of the elbow with a 0.2-T dedicated system

The purpose of this study was to evaluate MR imaging findings of the common extensor tendon in patients with lateral epicondylitis and asymptomatic volunteers studied on a 0.2-T dedicated system. In 23 patients (age range 29–58 years, mean age 47 years) with clinical symptoms of lateral epicondylitis MR imaging was performed using T1-, T2- and contrast-enhanced T1-weighted spin-echo sequences. In addition, the elbows of seven healthy volunteers (age range 22–29 years, mean age 25 years) and the symptom-free contralateral elbow of 11 of the 23 patients (age range 29–58 years, mean age 47 years) were studied as controls. Five patients were surgically treated after the MR examination and the results of histopathology were correlated with MR findings. Of the patients, 95.6 % showed intratendinous signal intensity changes on T1-weighted images on the symptomatic side. In 69.6 % signal alterations were observed on T2-weighted sequences and in 56.5 % an intratendinous contrast enhancement was present. Histopathology showed fibrovascular proliferation and fatty degeneration in patients with distinct signal intensity changes and contrast enhancement. Patients with only minor signal intensity changes on T1- and T2-weighted sequences and no contrast enhancement demonstrated fibrosclerotic degeneration and intratendinous cartilage formation in histopathology. The contralateral elbow showed signal intensity changes in 6 of 11 (54.5 %) cases on T1-weighted images and in 3 of 11 (27.3 %) on T2-weighted images. In the group of healthy volunteers minor signal intensity changes of the common extensor tendon could be seen in only 1 case. In patients with lateral epicondylitis of the elbow the type and extent of pathologic changes within the common extensor tendon can be evaluated using a dedicated low-field MR system. On the basis of MR imaging findings a more specified therapy planning among the variety of treatment modalities can be achieved. Received: 10 April 1998; Revision received: 13 October 1998; Accepted: 25 November 1998     

Peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images: correlation with macroscopic and microscopic findings in elderly cadavers

Objective. To correlate the peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images with the macroscopic and microscopic findings in cadavers derived from elderly subjects. Design. Twenty-eight intervertebral disks (16 lumbar and 12 cervical) derived from four nonembalmed cadavers were examined with T1-weighted spin echo and proton density-weighted and T2-weighted fast spin echo MR imaging. The signal intensities of the annulus fibrosus were evaluated on sagittal MR images and correlated with the findings on corresponding sagittal anatomic sections. The MR imaging-histologic correlation was then studied. Results. Peripheral focal low signal intensity areas and adjacent regions of high signal intensity were found in five lumbar intervertebral disks. Peripheral focal low signal intensity regions consisted of disorganized compact annular fibers, tiny fissures, and dense fibrosis. The high signal intensity regions, adjacent to the areas of low signal intensity, consisted of mucoid degeneration, tiny fissures, and chondroid metaplasia. Conclusions. Awareness of the histologic findings in regions that reveal peripheral focal low signal intensity with adjacent regions of high signal intensity in the degenerated annulus fibrosus on T2-weighted images may facilitate effective interpretation of clinical MR images of the spine. Received: 11 November 1998 Accepted: 20 January 1999     

MR imaging of subchondral osteonecrosis of the vertebral body after percutaneous laser diskectomy.

OBJECTIVE: We describe four cases of subchondral osteonecrosis of the vertebral body that occurred after percutaneous laser diskectomy. Follow-up MR imaging after laser intervention showed abnormal findings in the vertebral body immediately adjacent to the site of diskectomy that are consistent with subchondral osteonecrosis. CONCLUSION: MR imaging features of this complication include a wedge-shaped low signal intensity on T1-weighted images, high and low signal intensities on T2-weighted images, and a contrast-enhanced area corresponding to high signal intensity on T2-weighted images. Possible causative mechanisms include thermal injury and photoacoustic shock.     

MR and CT in cytoplasmically inherited striatal degeneration

A rare, cytoplasmically inherited striatal degeneration associated with Leber's optic atrophy exhibited selective symmetric low-density lesions in the putamen on the CT scan in five patients. The CT findings, however, were asymmetric (one patient) and subtle in the early phases of the disease. Occasionally, caudate lesions were demonstrable. On MR imaging, the lesions had high signal intensity on T2-weighted images and low signal intensity on T1-weighted images. This group of patients was distinguished from patients with other causes of striatal degeneration by a lack of hemispheric, brainstem, or cerebellar atrophy.     

Usual and unusual MRI findings of ovarian fibroma: correlation with pathologic findings.

Ovarian fibromas typically exhibit low signal intensity on T(2)-weighted images, which reflects their abundant fibrocollagenous stroma. However, the mass of larger tumors often demonstrates high signal intensity on T(2)-weighted images, which reflects varied degenerative changes, such as cystic degeneration, edematous change, hemorrhagic infarction, or necrosis caused by torsion and myxomatous change. We illustrate typical and atypical magnetic resonance (MR) imaging findings of ovarian fibromas and correlate them with histopathologic findings.     

MR imaging for evaluation of severe facial nerve damage in patients with facial nerve palsy

PURPOSE: To evaluate the usefulness of MR imaging for the detection of severe facial nerve damage in patients with facial nerve palsy. MATERIALS AND METHODS: We retrospectively reviewed 26 consecutive patients with facial nerve palsy (13 non-responders and 13 responders). T1-weighted, T2-weighted, and postcontrast T1-weighted images were obtained in all patients. FLAIR images were also obtained in 3 non-responders. RESULTS: The geniculate ganglion, labyrinthine segment, and tympanic segment or mastoid segment showed high signal intensity on T2-weighted images in 9 of 13 non-responders, whereas high signal intensity of the nerve was only seen in 1 of 13 responders. FLAIR imaging revealed high signal intensity lesions of the distal intrameatal segment in 2 non-responders. Contrast enhancement of the facial nerve showed a similar pattern in non-responders and responders. High signal intensity lesions on T2-weighted or FLAIR images showed enhancement on postcontrast T1-weighted images. CONCLUSION: These results suggest that a high signal intensity area on T2-weighted images is a marker of severe facial nerve damage. FLAIR imaging is useful for identification of T2-prolongation in the distal intrameatal segment.     

Relationship between MR imaging and histopathologic findings of the brain in extremely sick preterm infants.

BACKGROUND AND PURPOSE: MR imaging can now be used safely in extremely preterm infants. The aim of this study was to compare the MR imaging appearance of the immature brain with neuropathologic findings at postmortem examination. METHODS: Seven extremely sick preterm infants, born at a median of 24 weeks' gestation, were studied using T1- and T2-weighted MR sequences. Infants died at a median of 3 days after initial MR imaging, and postmortem examinations were carried out. RESULTS: The cortex and germinal matrix were seen as areas of low signal intensity on T2-weighted images, which corresponded to their highly cellular histologic appearance. The periventricular and subcortical layers of white matter had a high signal intensity, corresponding to high fiber and relatively low cellular density; the intermediate layer of low signal intensity corresponded to a dense band of migrating cells. Regions of acute hemorrhage were seen as low signal intensity and regions of infarction as high signal intensity on T2-weighted images. One infant with mild periventricular leukomalacia had some low signal intensity on T1-weighted images, but no focal changes on T2-weighted images. Regions of neuronal mineralization, seen in association with infarction and capillary proliferation, within the basal ganglia and thalami were characterized by very low signal intensity on T2-weighted images and by very high signal intensity on T1-weighted images. There were no imaging abnormalities detected in regions with more subtle histologic abnormalities, such as increased glial or apoptotic cells. CONCLUSION: MR imaging can be used to observe normal developing brain anatomy in extremely premature infants; it can detect areas of hemorrhage and infarction within the developing brain, but conventional MR imaging may not detect more subtle histologic abnormalities.     

Magnetic resonance imaging findings in patients with medial epicondylitis

Objective To compare the MR imaging findings of 13 patients with clinically diagnosed medial epicondylitis with the MR imaging findings of 26 patients of similar age with no clinical evidence of medial epicondylitis.Design and patients The study group consisted of 13 patients with clinically diagnosed medial epicondylitis. The control group consisted of 26 patients of similar age with no clinical evidence of medial epicondylitis. The medical records and MR imaging findings of these patients were retrospectively reviewed by two fellowship-trained musculoskeletal radiologists.Results Eleven of the 13 patients in the study group had thickening and increased signal intensity of the common flexor tendon on both T1-weighted and T2-weighted images. The remaining two patients in the study group had soft tissue edema around a normal-appearing common flexor tendon. Twenty-one of the 26 patients in the control group had a normal-appearing common flexor tendon on MR imaging. Three patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on T1-weighted images but of uniform low signal intensity on T2-weighted images. Two patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on both T1-weighted and T2-weighted images. None of the patients in the control group had soft tissue edema around the common flexor tendon.Conclusion MR imaging findings of patients with clinically diagnosed medial epicondylitis included thickening and increased T1 and T2 signal intensity of the common flexor tendon and soft tissue edema around the common flexor tendon. The presence of intermediate to high T2 signal intensity or high T2 signal intensity within the common flexor tendon and the presence of paratendinous soft tissue edema were the most specific findings of medial epicondylitis on MR imaging.     

Spring ligament complex: MR imaging-anatomic correlation and findings in asymptomatic subjects

PURPOSE: To use magnetic resonance (MR) imaging to assess the anatomy of the spring ligament complex (SLC) in cadaveric feet and to prospectively evaluate the MR imaging depiction of this complex in asymptomatic subjects. MATERIALS AND METHODS: Cadaveric feet were obtained and used according to institutional guidelines and with institutional approval and consent from the donors (before death) or the appropriate family members. Healthy volunteers were examined, with institutional review board approval and informed consent from each volunteer. MR imaging findings of the SLC in five cadaveric feet were analyzed and correlated with the findings in dissected foot specimens. Then, the MR imaging findings in the feet of 78 asymptomatic subjects were analyzed. For all three parts of the SLC, visibility, optimal imaging plane, and signal intensity characteristics were analyzed. The thicknesses of all SLC parts were measured. The measurements obtained in men and women were compared by using the Mann-Whitney U test, and Pearson correlation coefficients for associations between ligament thickness and subject age and sex were calculated. RESULTS: In the cadaveric feet, MR imaging enabled differentiation of all three parts of the SLC. The superomedial calcaneonavicular ligament (CNL) was visible in all; the medioplantar oblique CNL, in 60; and the inferoplantar longitudinal CNL, in 71 volunteers. The superomedial CNL had a mean thickness of 3.2 mm, was best seen on transverse oblique or coronal MR images, and had mainly intermediate signal intensity on T1-weighted images and low signal intensity on T2-weighted images. The medioplantar oblique CNL had a mean thickness of 2.8 mm, was best seen on transverse oblique MR images, and had mainly a typical striated appearance on T1- and T2-weighted images. The inferoplantar longitudinal CNL was the thickest (mean thickness, 4.0 mm), was best seen on coronal MR images, and had mainly intermediate signal intensity on T1-weighted images and variable signal intensity on T2-weighted images. Women had significantly thinner superomedial (mean thickness, 3.3 vs 3.5 mm; P = .015, Mann-Whitney U test) and inferoplantar longitudinal (mean thickness, 3.8 vs 4.2 mm; P = .02) CNLs than men. There was no significant correlation between ligament thickness and subject age. CONCLUSION: The superomedial and inferoplantar longitudinal CNLs are consistently visible portions of the SLC. The medioplantar oblique ligament is thinner, is seen less consistently, and has mainly a characteristic striated MR imaging appearance.