Comparison of the Long-Term Results of R3 and R4 Sympathicotomy for Palmar Hyperhidrosis

BACKGROUND: Video-assisted thoracoscopic sympathicotomy has been determined to be the best way to treat palmar hyperhidrosis. However, satisfaction with the surgical outcomes decreases with the onset of compensatory hyperhidrosis (CH) over time. The ideal level of sympathicotomy is controversial. Therefore, we compared the long-term results of R3 and R4 sympathicotomy. METHODS: We retrospectively reviewed 186 patients who underwent video-assisted thoracoscopic sympathicotomy between September 2001 and September 2015. We analyzed the long-term results with respect to hand sweating and CH, and the overall satisfaction in 186 patients. RESULTS: With respect to hand sweating, significantly more patients complained of overly dry hands in the R3 group (25% versus 3.7%, p<0.001) and of mildly wet hands in the R4 group (2.9% versus 13.4%, p=0.007). There was a significantly increased occurrence rate of CH in the R3 group (97.1% versus 65.9%, p< 0.001). The most frequent site of CH was the trunk area. The overall satisfaction was higher in the R4 group, but without significance (75% versus 85.4%, p=0.082). Significantly more patients reported being very satisfied in the R4 group (5.8% versus 22.0%, p=0.001). CONCLUSION: The R4 group had a higher rate of satisfaction than the R3 group with respect to hand sweating. CH and hand dryness were significantly less common in the R4 group than in the R3 group. The lower occurrence of hand dryness and CH resulted in a higher satisfaction rate in the R4 group.

Early Aggressive Surgical Treatment of Multiloculated Empyema

BACKGROUND: Empyema is the collection of purulent exudate within the pleural space. Overall, 36%–65% of patients with empyema cannot be treated by medical therapy alone and require surgery. Multiloculated empyema is particularly difficult to treat with percutaneous drainage. Therefore, we describe our experiences with early aggressive surgical treatment for rapid progressive multiloculated empyema. METHODS: From January 2001 to October 2015, we retrospectively reviewed 149 patients diagnosed with empyema who received surgery. The patients were divided into 2 groups according to whether they underwent emergency surgery or not. We then compared surgical outcomes between these groups. RESULTS: The patients in group A (emergency surgery, n=102) showed a more severe infectious state, but a lower complication rate and shorter length of hospital stay. The incidence of lung abscess was higher in group A, and abscesses were associated with diabetes and severe alcoholism. CONCLUSION: Early aggressive surgical treatment resulted in good surgical outcomes for patients with rapid progressive multiloculated empyema. Furthermore, we suspect that the most likely causes of multiloculated empyema are lung abscesses found in patients with diabetes mellitus as well as severe alcoholism.

Prolonged Air Leakage Caused by Mesenchymal Cystic Hamartoma of the Lung

A 16-year-old girl was transferred to the department of thoracic and cardiovascular surgery because of a spontaneous pneumothorax with prolonged air leakage. Chest computed tomography demonstrated a cystic lesion measuring 2×3 cm and involving the left upper lobe. Left upper lobectomy was performed via video-assisted thoracoscopic surgery. A pathologic examination of the specimen revealed a mesenchymal cystic hamartoma. Despite the rarity of pulmonary mesenchymal cystic hamartoma, it should be considered a potential cause of pneumothorax for patients with a large pulmonary cyst. Further, surgical resection must be considered because serious complications such as hemothorax, hemoptysis, and malignant transformation have been reported.

Electrocautery-Ignited Surgical Field Fire Caused by a High Oxygen Level during Tracheostomy

Tracheostomy is a relatively common surgical procedure that is performed easily in an operating room or intensive care unit. Open tracheostomy is needed in patients requiring prolonged ventilation when percutaneous tracheostomy is inappropriate. Sometimes, it is difficult to achieve bleeding control in the peritracheal soft tissue, and in such cases, we usually use diathermy. However, the possibility of an electrocautery-ignited surgical field fire can be overlooked during the procedure. This case report serves as a reminder that the risk of a surgical field fire during tracheostomy is real, particularly in patients requiring high-oxygen therapy.

Surgical treatment of airway obstruction in infants with Pierre Robin sequence

The deformities of micrognathia and glossoptosis in the newborn are frequently associated with a cleft palate, which is known as Pierre Robin sequence. Upper airway obstruction is the most serious problem in these patients. Treatment of Pierre Robin sequence includes either positional or surgical intervention. Mild cases are often managed in the prone position. However, when the patient fails to thrive due to chronic upper airway obstruction, or severe respiratory distress ensures despite positional treatment, surgical intervention is mandatory to relieve the obstruction. We experienced three infants with Pierre Robin sequence who showed a symptom triad of micrognathia, glossoptosis, and cleft palate. Intermittent cyanosis, depression of the chest, respiratory difficulty and feeding problems were also observed. To relieve severe upper airway obstruction caused by micrognathia and glossoptosis, we simultaneously performed modified tongue lip adhesion (TLA) and a subperiosteal release of the floor of the mouth (SRFM). Respiratory and feeding difficulties were relieved, the tongue positioned anteriorly, body weight increased, and mandibular growth improved. Simultaneous TLA and SRFM may constitute a simple and reliable method for surgical treatment of airway obstruction in patients with Pierre Robin sequence.

Absent Bow-Tie Sign in Knee MRI

PURPOSE: 'Absent bow-tie sign'is interpreted as positive when a bow-tie-shaped body segment is seen on only one or no slice of 4- or 5-mm thick sagittal images, and is a well known as a useful sign in diagnosing bucket-handle meniscal tears. In practice, however, we have found that this sign was also positive in certain cases other than bucket-handle tears. We have assumed that if the normal range of meniscal body width, as determined among Westerners, is transferred to the Korean population without verification and modification this might lead to misdiagnosis. The purpose of this study, therefore, is to examine the reliability of the 'absent bow-tie sign'. MATERIALS AND METHODS: Among 454 cases in which knee MRI had been performed, we retrospectively evaluated 862 menisci, the total remaining after cases of discoid meniscus or those involving previous meniscectomy had been excluded. Among the 862 menisci, 614 were normal, 97 showed degeneration, 43 showed buck-et-handle tearing, and 108 showed tears other than bucket-handle tear. In all cases, proton-denwity and T2-weighted images were obtained in both sagittal and coronal planes, with 3mm section thickness and 1mm gap. We recorded the number of sagittal images in which the body segment of each meniscus had a bow-tie appear-ance, and measured the width of each meniscal body, as seen on midcoronal images. RESULTS: In all cases but one of bucket-handle tears (97.7%), the bow-tie sign was absent, as it was in 73.2% ofnon-bucket-handle tears, 35.0% of degenerated menisci and 27.5% of normal menisci. Among the non-tear group, 56.4% of menisci in the female group and 27.1% in the male group had bodies less than 9mm wide. CONCLUSION: In the diagnosis of bucket-handle tears, the 'absent bow-tie sign'is a very sensitive indicator. It is nonspecific, however, and merely suggests some significant deficiency in the meniscus body or small menis-ci,so can be positive in other cases. Thus the interpreter should be aware of the characteristics of this sign especially when used to interpret MRI of the knee of a female Korean patient.

Papillary Tumors of the Breast: US Findings of the Benign and Malignant Lesions

PURPOSE: To determine which sonographic findings usefully differentiate between benign and malignant papillary tumors. MATERIALS AND METHODS: We retrospectively rev i ewed the ultrasonographic findings of 42 surgically proven cases of papillary breast lesions [11 malignant lesions (7 inva s i ve papillary carcinomas, 4 intraductal papillary carcinomas) and 31 benign intraductal pa-pillomas]. All 42 cases were classified sonographically as cystic or ductal, or solid type, and the shape, wall change, margin, internal echo-pattern, posterior echo change and other associated findings for the two types were then analysed. RESULTS: Among the 25 cases (5 malignant and 20 benign) of cystic or ductal type, tubular shaped lesions were more frequently benign (60%). In all 20 benign lesions the wall of cystic portion was well-defined, smooth and thin. The solid portion of the cystic type showed an illdefined irregular margin in four malignant lesions (80%) and a smooth margin in 19 which were benign (95%). The internal echo-pattern was heterogeneous mixed-echo in three cases of malignancy, and homogeneously hypoechoic in 19 benign lesions (95%). Posterior enhancement was seen in two malignant lesions (40%), while in 19 benign lesions (95%), there was no posterior echo change. There were 17 solid type lesions (6 malignant cases, 11 benign cases), and most of these, whether benign or malignant, were smooth, oval or lobulated, hypoechoic masses. Posterior enhancement, howeve r, was more frequently observed in malignant lesions (three cases, 50%) than in those which were benign (one case, 9%). CONCLUSION: In cystic or ductal type lesions, an ill-defined irregular thick cystic wall, an illdefined irregular margin, a heterogeneous mixed internal echo-pattern and posterior enhancement of the solid portion suggested malignancy. In solid type lesions, posterior enhancement was more frequently found in malignant than in benign lesions.

Interactive Atlas Using Web Bowser: CT and MRI of the Temporal Bone

PURPOSE: The purposes of this study were to construct an interactive atlas of the temporal bone using a web-browser and to provide a template for web-based teaching files, using free and shared applets and scripts on the internet. MATERIALS AND METHODS: HRCT and MR images of the temporal bone including its normal anatomy, tumors, trauma, inflammation, anomalies and vascular diseases were used in this study. Acquired radiologic images were transformed to GIF/JPG formats and to achieve appropriate image quality, were retouched. Text and image files of normal anatomy and diseases were written by HTML. JavaScript and applets were inserted in the HTML files for the interactive display of images and texts. In order to review anatomic features and diseases, a sarch index was also attached to the last part of the file. RESULTS: Using interactive images and texts, temporal bone anatomy and disorders were displayed. Scripts and applets were also useful for indicating specific points of interest when a mouse was placed over the anatomic sites. The atlas may be viewed in the form of a CD-ROM, or via the internet using any computer platform or web-browser. CONCLUSION: This web-based teaching file of the temporal bone offers dynamic and interactive education. It can be usefully employed as a template for the production of interactive educational materials, offering JavaScript and Providing suitable input for classes. It can replace texts and imaging contents.

MRI of Ganglion Cysts in Uncommon Sites or with Atypical Appearance

Ganglion cysts are common lesions which are most often found around the hands and feet. Magnetic resonance (MR) imaging is seldom performed; cysts are identified incidentally on MR images obtained for the purpose of evaluating other disorders. Clinically complicated ganglions are often confused with other more serious tumors, and MR examination is thus requested. Ganglions arising from uncommon sites or showing unusual MR findings can lead to wrong diagnosis. Thus, a thorough knowledge of potential sites and of the MR findings of unusual ganglion cysts can prevent mistake s. We therefore describe the MR findings of unusual ganglion cysts, including complicated ganglions, cruciate ligament ganglion cysts, meniscal cysts, labral cysts, ganglions in shoulder notches and tarsal tunnels, and intermuscular ganglion cysts.

MRI of Bucket-Handle Tears of the Meniscus of the Knee

PURPOSE: To determine the frequency of the MRI signs of meniscal bucket - handle tears already known as the double PCL sign, the flipped meniscus sign, the absent bow-tie sign, and the fragment-in-notch sign, and to compare the sagittal with the coronal images. MATERIALS AND METHODS: We retrospectively rev i ewed the MR findings of 37 patients in whom an initial interpretation of MR images had suggested meniscal bucke t - handle tears. All underwent subsequent arthroscopic evaluation and in 28, bucke t - handle tears were confirmed. Sagittal double-echo and coronal fat-suppressed double-echo T 2 - weighted images were obtained. Sagittal images were evaluated to determine whether or not signs of bucket-handle tear were evident, and coronal images we r e checked for a torn meniscus with displaced fragment. We also evaluated the MR findings of the nine false positive cases. RESULTS: The prevalence rate of absent bow-tie, double PCL, fragment-in-notch, and flipped meniscus signs was 96.4%, 53.6%, 17.9%, and 10.7%, respective l y. The detection rate for displaced fragment was higher with coronal images (92.9%) than with sagittal images (78.6%). Among the nine false positive cases, a longitudinal tear in the discoid meniscus was most common. A false-positive diagnosis was much more frequent on sagittal than on coronal images. CONCLUSION: The prevalence rate of absent bow-tie sign was very high, but was accompanied by a relatively high rate of misinterpretation. Coronal fat-suppressed T2- weighted images provided more reliable clues for the diagnosis of bucket-handle tears, with a high detection rate of displaced fragment.

MRI of Bucket-Handle Tears of the Meniscus of the Knee

PURPOSE: To determine the frequency of the MRI signs of meniscal bucket - handle tears already known as the double PCL sign, the flipped meniscus sign, the absent bow-tie sign, and the fragment-in-notch sign, and to compare the sagittal with the coronal images. MATERIALS AND METHODS: We retrospectively rev i ewed the MR findings of 37 patients in whom an initial interpretation of MR images had suggested meniscal bucke t - handle tears. All underwent subsequent arthroscopic evaluation and in 28, bucke t - handle tears were confirmed. Sagittal double-echo and coronal fat-suppressed double-echo T 2 - weighted images were obtained. Sagittal images were evaluated to determine whether or not signs of bucket-handle tear were evident, and coronal images we r e checked for a torn meniscus with displaced fragment. We also evaluated the MR findings of the nine false positive cases. RESULTS: The prevalence rate of absent bow-tie, double PCL, fragment-in-notch, and flipped meniscus signs was 96.4%, 53.6%, 17.9%, and 10.7%, respective l y. The detection rate for displaced fragment was higher with coronal images (92.9%) than with sagittal images (78.6%). Among the nine false positive cases, a longitudinal tear in the discoid meniscus was most common. A false-positive diagnosis was much more frequent on sagittal than on coronal images. CONCLUSION: The prevalence rate of absent bow-tie sign was very high, but was accompanied by a relatively high rate of misinterpretation. Coronal fat-suppressed T2- weighted images provided more reliable clues for the diagnosis of bucket-handle tears, with a high detection rate of displaced fragment.

MR Findings of Nasal Cavity Lesions Showing the Infundibular Widening on CT

PURPOSE: Several kinds of nasal cavity lesions located in the region of the infundibulum on CT. At such time,the visualization of these lesions is very sinilar. The purpose of this study was to differentially diagnose thesenasal cavity lesions through evaluation of the MR findings. MATERIALS AND METHODS: In 51 cases of pathologicallyproven nasal cavity masses which on CT showed infundibular widening, we retrospectively evaluated the MR findings.The cases involved prolapsed antral mucosa from sinusitis(n=15), inverted papilloma(n=10), antrochoanalpolyp(n=10), aspergillosis(n=9), and nasal polyp(n=7). All patients underwent both CT and MR. imaging. RESULTS: In all cases, CT findings were similar ; soft tissue masses filling the maxillary sinus and nasal cavity wereassociated with infundibular widening caused by pressure on the uncinate process, leading to erosion. Differentialdiagnosis by CT was very difficult ; MR T2 weighted imaging was most effective for differential diagnosis of thesenasal cavity masses. Prolapsed antral mucosa showed central inhomogeneous mixed signal intensity, with aperipheral rim of hyperintensity along the sinus wall and nasal component. Antrochoanal polyps showed homogeneousbright signal intensity of the antral and nasal component. Aspergillosis showed central dark signal foci. Invertedpapillomas showed mixed intermediate and high intensity mixed with high signal intensity. Nasal polyps showedstriation mixed of intermediate and high signal intensity, while nasal polyp showed striation of intermediate andhigh intensity. On Gd-enhanced T1 weighted images, prolapsed antral mucosa and antrochoanal polyp showedperipheral rim enhancement of the antral and nasal component. In contrast, inverted papilloma and nasal polypshowed intense enhancement of the mass and can be separate from the sinus inflammatory disease. CONCLUSION: Various nasal cavity masses showing infundibular widening on CT can be differentiated on MR images, especially ofthese are T2 weighted or contrast enhanced T1 weighted.

Cholesteatoma of the Temporal Bone: MR Findings

PURPOSE: The purpose of this study is to evaluate the diagnostic capability of MR imaging for distinguishingcholesteatoma from other causes of inflammation. MATERIALS AND METHODS: We prospectively evaluated the MR imagesof 17 patients with a fully opacified middle ear in whom CT of the temporal bone suggested cholesteatoma. Allpatients underwent middle ear surgery and cholesteatoma was verified in 15 cases, granulation tissue in 15,cholesterol granuloma in four and hemotympanium in one. For each lesion, MR and pathologic findings werecorrelated. RESULTS: All cases of cholesteatoma showed low to intermediate signal intensity on T1-weightedimages. On T2-weighted images, 11 cases showed high signal intensity, while seven were less than CSF and four werethe same. Four cases revealed central low signal intensity with peripheral rim of high signal intensity. On GdDTPA-enhanced images, peripheral or marginal enhancement due to surrounding granulation tissue was noted in 12cases. Two appeared to be totally enhanced. One case of congenital cholesteatoma showed no enhancement. OnT2-weighted images, all cases of granulation tissue showed high signal intensity, and on neither T1- norT2-weighted images could these be distinguished from cholesteatoma. On Gd DTPA-enhanced study, all cases ofgranulation tissue were enhanced, and on T1WI, all cases of cholesterol granuloma showed homogeneous bright signalintensity on T1WI. One case of cholesterol granuloma in the mastoid showed bright signal intensity mixed withirregular areas of dark signal intensity. A further comparison of MR imaging with CT is that two case oflabyrinthitis and one of meningitis were diagnosed on Gd- enhanced T1-weighted images. CONCLUSION: Todifferentiate cholesteatoma from granulation tissue and cholesterol granuloma by the evaluation of their signalintensities and enhancement patterns, MR imaging is superior to CT. When there are cholesteatoma-associatedcomplications such as labyrinthitis or meningitis, postcontrast MR imaging can provide better information.

CT and MR evaluation of Choanal Polyps

PURPOSE: To evaluate the various types and CT and MR imaging findings of choanal polyps. MATERIALS AND METHODS: We classified 42 cases of surgically proven choanal polyps into three types according to site of origin,and retrospectively analyzed imaging findings; in the case of antrochoanal polyps, particulr attention was givento extension of the lesion into the nasal cavity. We also determined whether MR imaging can provide moreinformation than CT. RESULTS: The antrochoanal polyp was the most common type( 33/42 : 78.6% ). Three cases ofchoanal polyps(7.1%) originated in the sphenoid sinus (sphenochoanal polyps), and while six( 14.3% ) did notinvolve the sinus( pure choanal polyps ). Thirty-six of 42 choanal polyps(85.7%) extended into either the choanaor nasopharynx. Three cases of antrochoanal polyps protruded through the middle meatus, and two into theoropharynx. The maxillary sinus component of an antrochoanal polyps extended more frequently through the accessoryostium( 29/33 ) than through the natural ostium. For delineating the stalk of an antrochoanal polyp, MR imagingwas not superior to CT. CONCLUSION: The most common type of choanal polyp is the antrochoanal, followed by purechoanal and sphenochoanal. CT and MR imaging can help identify lesion continuity between a choanal polyp and theparanasal sinus.

Solid Breast Lesions: Evaluation with Power versus Conventional Color Doppler Sonography

PURPOSE: To compare power and conventional color Doppler sonography for depiction of the vasculature of solidbreast lesions, and to evaluate the usefulness of power Doppler sonography for differential diagnosis of malignantbreast lesions. MATERIALS AND METHODS: In order to detect vascularity, 82 cases of solid breast lesions wereevaluated by power and color Doppler sonography. Fifty-eight pathologically proven cases (37 benign and 21malignant lesions) were analyzed for the amount and patterns of Doppler signals, morphology of vessels, and thediagnostic accuracy. RESULTS: In 45 of 82 cases, power Doppler sonography depicted flow better than did colorDoppler sonography, while in 37 cases, depiction was equal. On power Doppler sonography, the incidence of markedblood flow in malignant lesions was three times higher than in benign lesions. The pattern of vasculature was morepredominantly central (85.5 %) and penetrating (61.9 %) in malignant lesions than in benign lesions. Branching(57.1 %) and disordered vessels (33.3 %) were more frequent in malignant lesions than in benign. For the diagnosisof malignancy, sensitivity for power Doppler sonography was 65 %, specificity was 79 % and diagnostic accuracy was74.1 % ; for color Doppler sonography, the corresponding figures were 76.9 %, 75.6 % and 75.9 %. CONCLUSION: Power Doppler sonography was more sensitive than color Doppler sonography for the detection of flow in solidbreast lesions. For the differentiation of benign from malignant lesions, however, there was no difference indiagnostic accuracy between the two modalities. findings of central and penetrating distribution patterns ofDoppler signals, and branching and disordered shapes of vessels, along with other sonographic criteria, arehelpful for predicting malignancy.

MRI of Breast Implant-related Complications

PURPOSE: To assess the usefulness of MRI in the preoperative diagnosis of breast implant-relatedcomplications. MATERIALS AND METHODS: Thirty four breast implants in 17 patients were examined. Eight breasts hada history of repeated surgery due to rupture and in eight others, simultaneous interstitial silicone injection hadbeen performed. MR images of the 34 implants were prospectively analyzed for implant-related complications,without prior clinical information, and the findings were compared with the results of surgery. RESULTS: Theimplant-related complications seen on MRI were infections in three cases, seromas in two, and implant malpositionin two. The linguine sign was seen in eight cases and intraparenchymal silicone in 17. Among the 32 removedimplants, rupture was genuine in ten cases (nine, extracapsular; one, intracapsular). In evaluating the MRfindings of implant rupture, the linguine sign showed 80% sensitivity, 100% specificity and 93.8% accuracy.Intraparenchymal silicon also revealed high sensitivity (90%), but relatively low specificity and accuracy (63.7%and 71.9%, respectively); this was due to the difficulty of differentiating granulomas still present after aprevious rupture from injected silicone material. MRI was useful for visualization of implant migration, thedirect relationship of extended or extruded silicone in extracapsular rupture and the localization of siliconegranulomas, as seen on multiplanar images. The extent of infection was clearly demonstrated on contrast enhancedscan. There was relatively good correlation between the degree of contracture seen on physical examination andthat seen on MRI. CONCLUSION: MRI was an effective and useful method for the preoperative evaluation ofimplant-related complications; degree of contracture was successfully predicted.

Verification of the Reliability of Sagittal MR Images in Assessment of Segmental Instability of the Wrist

PURPOSE: To determine the reliability of carpal angle measurement using sagittal wrist MR images for thediagnosis of dorsal intercalated segmental instability (DISI) or ventral intercalated segmental instability(VISI). MATERIALS AND METHODS: In ten asymptomatic adult volunteers, capitolunate, scapholunate, and radiolunate angleswere measured on lateral radiographs and five different series of sagittal MR images, and compared andstatistically analysed. The four MR series, obained in a prone position, with the wrists over the head, were asfollows : A, sagittal images parallel to the third metacarpal bone axis, in a neutral position ; B, obliquesagittal images parallel to the fourthe metacarpal axis, in a neutral position, ; C and D, sagittal imagesparallel to the third metacarpal bone axis, with the wrist at 15degree radially and ulnarly deviated positions,respectively. The fifth true sagittal MR image (E) was obtained in a supine position with the wrists locatedbeside the trunk, in a neutral position. RESULTS: In the MR series performed in the prone position, thecapitolunate and radiolunate angles measured in the series A, B and D were significantly larger than those seen onlateral radiographs. The scapholunate angle showed a statistically significant difference(p=.014) in series D,where one case showed DISI configuration at a scapholunate angle of 81degree. In other series, the angles were notsignificantly different from those seen on lateral radiographs. CONCLUSION: The lunate appears more dorsallytilted on sagittal MR images obtained in the prone position with the wrists above the head than on lateralradiographs, and a DISI configuration can be minicked. IF diagnosing wrist segmental instability by interpretingsagittal MR images without lateral radiographs, there is potential risk of misdiagnosis. It is believed that wristpositioning is crucial for the correct measurement of angles.

Comparison of MR Myelography with Conventional Myelography in Lumbar Disc Diseases

PURPOSE: To compare MR myelography(MRM) using heavily T2 weighted fast spin echo(FSE) with conventional myelography in the evaluation of lumbar degenerative disc diseases. MATERIALS AND METHODS: A total of 50 patientswith lumbar degenerative disc diseases underwent both MRM and conventional myelography. A 1.5 T Signa MR systemwas used. For MRM, heavily T2 weighted FSE pulse sequences were performed in sagittal, coronal and both obliqueplanes. The images of MRM and conventional myelography were analyzed retrospectively and compared, focusing on the pattern of compression of the thecal sac and nerve roots. RESULTS: MRM yielded comparable images to conventional myelography in 68% (34/50). MRM was superior to conventional myelography in 11 cases (22%), and the opposite resulted in 5 cases(10%). MRM could visualize the spinal canal below the level of complete block in 6 patients,provided better contrast in the cases of dural ectasia in 3 cases and better delineation of individual nerve roots with source images in 1 case. Additional informations such as incidental retroperitoneal vascular malformation and extravasation of the CSF could be obtained by MRM in 1 case each. Disadvantages of MRM were poor contrast in thecases of multiple spinal stenosis, obscuration of the nerve roots by engorged paraspinal vessels, and occassional difficulty in defining the levels due to vanishment of the bony background image. CONCLUSION: MRM is a safe, noninvasive, nonionizing modality which in very effective in evaluating the lumbosacral disc disease. Use ofFSE-MRM in addition to the routine MR imaging could be very helpful not only for better evaluation of nerve roots but also for the additional informations.

MR Imaging of the Knee: Three-Dimensional Fourier Transform GRASS Technique

PURPOSE: To evaluate the usefulness of three-dimensional(3D) Fourier transform(FT) gradient refocused acquisition in steady state(GRASS) technique for MR imaging of the knee. MATERIALS AND METHODS : Sixty-three kneesin 61 patients were imaged on the 1.5T MR system. We compared 3DFT GRASS technique with 2D spin echo(SE) techniquein terms of conspicuousness of the lesions of internal knee structures based on the results of arthroscopy or open surgery. As a SE technique, sagittal T1-and T2-weighted, and coronal fat-suppressed T2-weighted sequences were performed. Sixty contiguous axial scans with 0.7 or 1mm section thickness were performed using 3D GRASS technique, and we also evaluated arbitrarily reformatted images produced from the original axial voxel images. RESULTS: For the depiction of the tear, 3DFT GRASS was superior to 2D SE in three cases of medial meniscus, one of later almeniscus, and two of anterior cruciate ligament. Specificity of 3D GRASS was also higher than that af 2D SE inevaluation of lateral meniscus and anterior cruiciate ligament. There was no significant difference in MR diagnosis for tears of the posterior cruciate, medial collateral, and lateral collateral ligaments. 3D GRASS was superior in evaluating the extent and morphology of the torn menisci. CONCLUSION: The 3DFT GRASS technique was comparable or even superior to the 2D SE technique in the evaluation of the internal structure of the knee, andcan be expected to supplement standard MR knee techniques, especially in complicated cases of meniscal orligamentous tears.

Intravenous Magnetic Resonance Arthrography of the Knee

PURPOSE: Knee IVIR images were repeatedly obtained after intravenous administration of gadopentetate dimeglumine to evaluate the arthrographic effect and to determine the optimal scan timing and technique. MATERIALS AND METHODS: Sagittal Tl-weighted (650/15) sequences were repeated before and after intravenous gadolinium enhancement in 26 patients who were divided into exercise (14/26) and nonexercise (12/26) groups. Fourteen patients in exercise group were allowed to move the affected knee joint actively for 10 minutes immediately after the first post-enhancement scan and before repeating scans. The signal intensities in central and peripheral portions of the joint were measured and compared between these two groups. RESULTS: In all cases, enhancement of joint fluid began at peripheral portion and progressed toward central portion. The diffusion rate in exercise group was far faster than that in nonexercise group and homogeneous arthrographic image was revealed within 10 minutes after completion of joint movement. The arthrographic effect continued and the rate of signal decrease was quite slow. CONCLUSION: MR arthrographic image of knee joint can be obtained within 10 minutes after completion of a few minute exercise following intravenous injection of gadopentetate dimeglumine. Intravenous MR arthrography is expected to become an useful method as a convenient alternative to direct MR arthrography.