Serial follow-up MR imaging after gamma knife radiosurgery for vestibular schwannoma

BACKGROUND AND PURPOSE: Gamma knife radiosurgery has become an important treatment option for vestibular schwannoma. The effect of treatment can be assessed only by neuroimaging. We analyzed the evolution of follow-up MR imaging findings after gamma knife radiosurgery to provide information for the clinical management of these tumors. METHODS: Changes in tumor volume and enhancement were assessed visually on 341 follow-up MR studies obtained in 78 of 86 consecutive patients with unilateral vestibular schwannoma who underwent gamma knife radiosurgery. RESULTS: Follow-up MR studies were obtained between 10 and 63 months (mean, 34 months) after treatment. Tumor control rate was 81%. Changes in tumor volume were classified as temporary enlargement (41%), no change or sustained regression (34%), alternating enlargement and regression (13%), or continuous enlargement (12%). Temporary enlargement occurred within 2 years after radiosurgery. Changes in tumor enhancement were classified as transient loss of enhancement (84%), continuous increase in enhancement (5%), or no change in enhancement (11%). There was no significant correlation between changes in tumor volume and tumor enhancement. Areas of T2 hyperintensity in adjacent brain tissue appeared in 31% of patients. CONCLUSION: Dynamic changes in vestibular schwannoma are seen on serial follow-up MR studies obtained after gamma knife radiosurgery. An increase in tumor size up to 2 years after radiosurgery is likely to be followed by regression. Changes in contrast enhancement are not predictive of clinical outcome. Neuroimaging follow-up is recommended.     

MR imaging of uterine carcinoma: correlation with clinical and pathologic findings

Thirteen patients with clinical stages I and II endometrial carcinoma were examined with magnetic resonance (MR) imaging before surgery. Depth of invasion and stage of disease were assessed, and the results were compared with those from MR images of the surgical specimens and pathologic findings. Staging with MR imaging was accurate in 11 of 13 patients (85%). Our results agree with previous reports that MR imaging is an accurate, noninvasive method of assessing depth of myometrial invasion and cervical involvement. We anticipate that MR imaging will have an increasing role in treatment of patients with endometrial carcinoma.     

MR imaging findings in autoimmune hepatitis: correlation with clinical staging

PURPOSE: To retrospectively evaluate the morphologic and enhancement features of the liver on magnetic resonance (MR) images obtained in patients with autoimmune hepatitis (AIH) and to determine if there is a correlation between MR imaging findings and severity of clinical disease as measured with the Mayo end-stage liver disease (MELD) score. MATERIALS AND METHODS: This study was compliant with the Health Insurance Portability and Accountability Act and approved by the institutional review board. The need for informed consent was waived. Thirty-two patients (29 female and three male patients; mean age, 44 years; age range, 14-69 years) undergoing treatment for AIH underwent unenhanced and gadolinium-enhanced MR imaging. Two radiologists reviewed all cases independently to determine the presence of patchy or heterogeneous liver enhancement, biliary duct changes, lymphadenopathy, and findings of portal hypertension. Fibrosis was graded as mild, moderate, or severe reticular (corresponding to a grading scale of 1-3) or as confluent. Agreement between radiologists was assessed by using kappa coefficients. Mean MELD scores were compared across fibrosis categories by using the Kruskal-Wallis analysis of variance. RESULTS: Of the 32 patients, two (6%) had no imaging findings of cirrhosis. Thirty patients (94%) had reticular fibrosis with a mean grade of 1.8. Six patients had confluent fibrosis, and all six had associated reticular fibrosis. Mild intrahepatic biliary duct dilatation involving the right and left lobes was observed in four patients (12%). Lymphadenopathy was observed in 12% of patients. None of the patients had hepatocellular carcinoma. There was no significant overall association between fibrosis grade and MELD score (P = .36). CONCLUSION: Although fibrosis is a common feature in AIH and is often moderate to severe, no significant correlation between fibrosis grade and MELD score was found.     

Osteoarthritis: MR imaging findings in different stages of disease and correlation with clinical findings

PURPOSE: To determine whether knee pain, stiffness, and limited function in patients with different stages of osteoarthritis correlate with the degree of disease assessed on magnetic resonance (MR) images and radiographs. MATERIALS AND METHODS: Radiographs in 50 patients with varying degrees of osteoarthritis of the knee were assessed by using the the Western Ontario and McMaster University (WOMAC) osteoarthritis index and the Kellgren-Lawrence (KL) scale. MR images were obtained and analyzed by two readers for cartilage lesions, bone marrow edema pattern, and ligamentous and meniscal lesions. RESULTS: Thirteen of 16 knees with a KL score of 4 showed full-thickness cartilage lesions and bone marrow edema pattern. Cruciate ligament tears were found in five of 12 knees with a KL score of 3 and in nine of 16 knees with a KL score of 4. While the KL score correlated significantly (P <.05) with the grade of cartilage lesions, and a substantially higher percentage of lesions with higher KL scores were found on MR images, the correlations between MR imaging findings and KL score versus clinical findings were not significant (P >.05). Significant differences between WOMAC scores were found only for the grades of cartilage lesions (P <.05). CONCLUSION: Cartilage lesions, bone marrow edema pattern, and meniscal and ligamentous lesions were frequently demonstrated on MR images in patients with advanced osteoarthritis. Clinical findings showed no significant correlations with KL score and extent of findings at MR imaging.     

Epithelioid sarcoma: clinical,MR imaging and pathologic findings

OBJECTIVE: To report and describe the MR imaging features of eight new cases of this rare soft tissue sarcoma and correlate them with the clinical and histologic findings.DESIGN AND PATIENTS. Retrospective analysis was carried out for the MR imaging characteristics and histologic findings of eight patients with pathologically proven epithelioid sarcoma and the literature was reviewed. Findings were correlated in each case with the patient's clinical presentation and eventual outcome.RESULTS: The patients, whose primary tumors ranged from 2.5 cm to 19 cm in maximum dimension, were 1 to 90 years of age. Tumors involved the extremities ( n=5), the scalp ( n=2) and the paraspinal muscles ( n=1). Five tumors presented as well-defined, frequently painful, deeply situated masses and three as subcutaneous nodules or cutaneous ulcers with no palpable mass. Four patients had associated regional lymphadenopathy and one had distant metastases at diagnosis. MR imaging showed tumor infiltration of adjacent tissues in seven patients. Signal characteristics reflected varying degrees of cellularity, and the presence of necrosis, hemorrhage, fibrosis, hyalinization and inflammation. Bone marrow involvement was demonstrated in one patient. Clinical outcomes were generally poor.CONCLUSIONS: Epithelioid sarcoma is an aggressive soft tissue sarcoma with a varied clinical presentation, growth pattern, MR signal characteristics and histologic picture. The tumor favors the distal extremities and is commonly infiltrative and accompanied by enlarged regional lymph nodes. This neoplasm may present as an intramuscular mass but should also be suspected in patients with ulcerating cutaneous nodules with or without regional lymphadenopathy.     

Prostate cancer: correlation of MR imaging and MR spectroscopy with pathologic findings after radiation therapy-initial experience

PURPOSE: To prospectively evaluate magnetic resonance (MR) imaging and MR spectroscopy for depiction of local prostate cancer recurrence after external-beam radiation therapy, with step-section pathologic findings as the standard of reference. MATERIALS AND METHODS: Study received institutional approval, and written informed consent was obtained. Study was compliant with Health Insurance Portability and Accountability Act. Sextant biopsy, digital rectal examination, MR imaging, MR spectroscopy, and salvage radical prostatectomy with step-section pathologic examination were performed in nine patients with increasing prostate-specific antigen levels after external-beam radiation therapy. MR imaging criterion for tumor was a focal nodular region of reduced signal intensity at T2-weighted imaging. MR spectroscopic criteria for tumor were voxels with choline (Cho) plus creatine (Cr) to citrate (Cit) ratio ([Cho + Cr]/Cit) of at least 0.5 or voxels with detectable Cho and no Cit in the peripheral zone. Sensitivity and specificity of sextant biopsy, digital rectal examination, MR imaging, and MR spectroscopy were determined by using a prostate sextant as the unit of analysis. For feature analysis, MR imaging and MR spectroscopic findings were correlated with step-section pathologic findings. RESULTS: MR imaging and MR spectroscopy showed estimated sensitivities of 68% and 77%, respectively, while sensitivities of biopsy and digital rectal examination were 48% and 16%, respectively. MR spectroscopy appears to be less specific (78%) than the other three tests, each of which had a specificity higher than 90%. MR spectroscopic feature analysis showed that a metabolically altered benign gland could be falsely identified as tumor by using MR spectroscopic criteria; further analysis of MR spectroscopic features did not lead to improved MR spectroscopic criteria for recurrent tumor. CONCLUSION: In summary, MR imaging and MR spectroscopy may be more sensitive than sextant biopsy and digital rectal examination for sextant localization of cancer recurrence after external-beam radiation therapy.     

Painful heel: MR imaging findings.

Heel pain is a common and frequently disabling clinical complaint that may be caused by a broad spectrum of osseous or soft-tissue disorders. These disorders are classified on the basis of anatomic origin and predominant location of heel pain to foster a better understanding of this complaint. The disorders include plantar fascial lesions (fasciitis, rupture, fibromatosis, xanthoma), tendinous lesions (tendinitis, tenosynovitis), osseous lesions (fractures, bone bruises, osteomyelitis, tumors), bursal lesions (retrocalcaneal bursitis, retroachilleal bursitis), tarsal tunnel syndrome, and heel plantar fat pad abnormalities. With its superior soft-tissue contrast resolution and multiplanar capability, magnetic resonance (MR) imaging can help determine the cause of heel pain and help assess the extent and severity of the disease in ambiguous or clinically equivocal cases. Careful analysis of MR imaging findings and correlation of these findings with patient history and findings at physical examination can suggest a specific diagnosis in most cases. The majority of patients with heel pain can be successfully treated conservatively, but in cases requiring surgery (eg, plantar fascia rupture in competitive athletes, deeply infiltrating plantar fibromatosis, masses causing tarsal tunnel syndrome), MR imaging is especially useful in planning surgical treatment by showing the exact location and extent of the lesion.     

Serial proton MR spectroscopic imaging of recurrent malignant gliomas after gamma knife radiosurgery

BACKGROUND AND PURPOSE: The diagnosis of brain tumors after high-dose radiation therapy is frequently limited by the lack of metabolic discrimination available with conventional imaging methods. The purpose of this study was to use proton MR spectroscopy to investigate serial changes in recurrent malignant gliomas after gamma knife radiosurgery to characterize tissue response to high-dose radiation. METHODS: Eighteen patients with recurrent gliomas were studied with MR imaging and 3D proton MR spectroscopic imaging at the time of radiosurgery and at regular time points thereafter. Choline (Cho) and N-acetyl aspartate levels were calculated on a voxel-by-voxel basis and compared with levels found in normal tissue and with levels observed at previous time points. The results of the spectral analysis were then compared with the radiologic findings. Statistical comparisons were precluded by the small sample sizes involved. RESULTS: Response within the gamma knife target was observed as a reduction of Cho levels and an increase in lactate/lipid levels, typically within 6 months of treatment. Increases in Cho correlated with poor radiologic response and suggested tumor recurrence, confirmed histologically in six cases. The development of a spectral abnormality preceded a coincident increase in contrast enhancement by 1 to 2 months in nine cases. CONCLUSION: Proton MR spectroscopic imaging provided diagnostic and monitoring information before and after radiosurgery. Evaluation of metabolic changes with proton MR spectroscopy and structural changes with MR imaging improved tissue discrimination and provided correlation with histologic findings.     

Ganglia of the tarsal sinus: MR imaging features and clinical findings

Purpose

To analyze MR imaging and clinical findings associated with ganglia of the tarsal sinus.

Materials and methods

In a record search, ganglia of the tarsal sinus were retrospectively identified in 26 patients (mean age 48 ± 16 years), who underwent MR imaging for chronic ankle pain. Images were reviewed by two radiologists in consensus for size and location of ganglia, lesions of ligaments of the ankle and the tarsal sinus, tendon abnormalities, osteoarthritis, osseous erosions and bone marrow abnormalities. Medical records were reviewed for patient history and clinical findings.

Results

Ganglia were associated with the interosseus ligament in 81%, the cervical ligament in 31% and the retinacula in 46% of cases. Signal alterations suggesting degeneration were found in 85%, 50% and 63% in case of the interosseus ligament, the cervical ligament and the retinacula, respectively. Scarring of the anterior talofibular ligament and the fibulocalcaneal ligament was found in 68% and 72% of the patients, respectively, while only 27% of the patients recalled ankle sprains. Ganglia at the retinacula were highly associated with synovitis and tendinosis of the posterior tibial tendon (p < 0.05).

Conclusion

All patients with ganglia in the tarsal sinus presented with another pathology at the ankle, suggesting that degeneration of the tarsal sinus may be a secondary phenomenon, due to pathologic biomechanics at another site of the hind foot. Thus, in patients with degenerative changes of the tarsal sinus, one should be alerted and search for underlying pathology, which may be injury of the lateral collateral ligaments in up to 70%.     

Stereotactic third ventriculostomy: assessment of patency with MR imaging

Ventricular CSF signal-intensity characteristics indicative of flowing CSF on MR images (CSF flow void) were analyzed in 20 patients who underwent a CT-based stereotactic third ventriculostomy for presumed internal obstructive hydrocephalus between October 1985 and June 1988. The status of all ventriculostomies was assessed postoperatively by radionuclide ventriculography. Postoperative MR and ventriculographic findings were correlated with the patients' subsequent clinical course. A CSF flow void in the anterior and inferior third ventricle, which seems to indicate vigorous pulsatile CSF flow through a functioning ventriculostomy, was present in all 19 patients who were clinically improved after ventriculostomy. In all 19 of these patients the radionuclide ventriculogram demonstrated normal CSF dynamics. One of the 20 patients did not improve postoperatively. The ventriculogram in this patient revealed delayed ventricular clearing and impaired CSF resorption, and the postoperative MR image did not demonstrate an anterior/inferior third ventricular CSF flow void. Eight of these patients were evaluated preoperatively by MR; one of these eight was the single nonimproved individual. None of the eight preoperative MR studies demonstrated a CSF flow void in the anterior/inferior third ventricle; however, this finding was present in seven of seven postoperative MR studies in clinically improved patients. We conclude that the presence of a CSF flow void in the anterior/inferior third ventricle on a postoperative MR examination is sufficient to document patency of a third ventriculostomy. The absence of this finding may be due to a nonpatent ventriculostomy or perhaps an extraventricular CSF obstruction. The more invasive ventriculogram may be reserved for this situation to distinguish between these latter two possibilities.     

脑转移瘤手运动区MR功能成像在伽玛刀治疗中的初步应用

目的探讨应用功能MR成像（fMRI）指导脑转移瘤伽玛刀剂量计划时保护手运动区的价值。方法10例毗邻手运动区的脑转移瘤患者行fMRI检查。剂量计划时，参考功能图像使手运动区所覆盖的等剂量曲线值低于30％。结果所有病例均有中央沟变形、伸长和移位，手运动区变形。9例病灶同侧活动指数（IAI）〈1，1例IAI〉1，中位数为0．51，9例患侧信号强度上升百分率（SIRP）为2．70，较健侧4．32低（Z=-2．248，P=0．025）。治疗后随访，9例患侧手肌力逐渐恢复，治疗后3个月IAI1．27（Z=-2．197，P=0．028）、SIRP5．22（Z=-2．807，P=0．005）以及治疗后6个月IAI1．39（Z=-2．366，P=0．018）、SIRP5．69（Z=-2．701，P=0．007）均大于伽玛刀治疗前，两者间变化差异有统计学意义。结论初步研究表明rMRI指导放射外科剂量计划，保护脑运动区。     

MR imaging findings of elastofibroma dorsi in correlation with pathological features: our experience

Purpose

This paper describes the role of magnetic resonance (MR) imaging for characterising elastofibroma dorsi in correlation with pathological findings.

Materials and methods

Over a period of 9 years, 1,233 MR examinations of the periscapular region assessed for the presence of elastofibroma dorsi with superconductive 1.5-T MR scanners at three different radiology institutes were retrospectively reviewed.

Results

Our study population included 15 patients (12 women, three men; mean age 58 years, range 28–82 years) presenting with 17 lesions. Two patients had bilateral elastofibroma dorsi. Thirteen of 15 patients underwent MR examination for clinical suspicion of a lesion located in the periscapular region, whereas in 2/15 cases it was an incidental finding during MR examination performed for other diseases. Diagnosis of elastofibroma dorsi was confirmed by histopathology in 11/17 cases. The remaining lesions were considered benign, as their size and morphology did not change over a mean follow-up period of 1.5 years.

Conclusions

MR imaging with its multiplanar capabilities and high-contrast resolution has a high level of accuracy in characterising elastofibroma dorsi and may avoid the need for biopsy or surgical operation.     

Gallbladder carcinoma: findings at MR imaging with MR cholangiopancreatography

PURPOSE: To describe magnetic resonance (MR) imaging and MR cholangiopancreatography (MRCP) findings in gallbladder carcinoma, and to correlate these findings with available surgical and biopsy information. METHODS: Preoperative MR images (T1-weighted spin-echo, T2-weighted fast spin-echo, single shot fast spin-echo, and dynamic gadolinium-enhanced gradient echo) in 34 patients with gallbladder carcinoma were retrospectively reviewed for appearance of the primary neoplasm and for demonstration of hepatic, peritoneal, duodenal, and nodal involvement. Imaging findings were then compared with surgical findings (n = 19 patients) and histologic findings (n = 15 patients). RESULTS: Gallbladder carcinoma manifested at MR imaging as focal gallbladder wall thickening with an eccentric mass in 76% (26/34) of cases. The most common types of regional spread demonstrated were direct liver invasion in 91% (31/34), lymphadenopathy in 76% (26/34), and biliary tract invasion in 62% (21/34). Sensitivity for direct hepatic invasion was 100%, and was 92% for lymph node metastasis. CONCLUSION: MRI and MRCP can provide information relevant to preoperative staging of gallbladder carcinoma.     

Sacroiliitis: MR imaging findings

Magnetic resonance (MR) imaging was performed in seven asymptomatic volunteers and 17 patients with clinical and radiologic evidence of sacroiliitis. MR imaging findings were compared with those at computed tomography (CT) to determine the MR imaging appearance of the sacroiliac joint when normal and in sacroiliitis. The normal articulation was well depicted with MR imaging. Findings of sacroiliitis were identified in 20 sacroiliac joints (12 patients). MR imaging findings characteristic of sacroiliitis included abnormal cartilage signal intensity (95% of joints) and erosions (75% of joints) on T1-weighted images. Areas of increased intensity in the articulation (80% of joints) or in erosions (60% of joints) were seen on T2-weighted images. MR imaging was superior to CT for evaluation of cartilage and detection of erosions. Four sacroiliac joints (20%) and two patients (17%) with MR imaging findings of sacroiliitis were negative at CT. The authors conclude that MR imaging is a valuable method for detecting sacroiliitis, particularly when results of other imaging techniques are inconclusive.     

Three-dimensional MR imaging of the coronary arteries: Preliminary clinical experience

A three-dimensional (3D) magnetization-prepared (MP) rapid gradient-echo (RAGE) and 3D RAGE technique was used to image the coronary arteries in healthy volunteers and patients with known disease. Each sequence produced images of volumes partitioned into 16 thin sections with differing blood-fat-myocardium contrast. The two types of images were subtracted to null fat signal, thus producing a third image set that showed flowing blood. Total imaging time was about 17 minutes. In the volunteers, the 3D MP-RAGE and subtraction images consistently showed the morphology of the right coronary artery. The left main and left anterior descending arteries were also well seen. The circumflex artery was less consistently identified. Of the 17 diseased coronary artery segments identified at catheterization, 16 had altered signal intensity (narrowing, occlusion, reduced contrast-to-noise ratio, irregularity) on the subtraction images, while 13 had altered signal intensity on the 3D MP-RAGE images. The results indicate that this 3D MP-RAGE and 3D RAGE technique has potential utility as a screening method for coronary heart disease.