Initial institutional experience of uncooled single-antenna microwave ablation for large hepatocellular carcinoma.

AIM: To evaluate the safety, efficacy, and feasibility of a novel microwave generator, designed to deliver automatically adjusted energy by tissue permittivity feedback control into the tumour via an uncooled antenna, in patients with larger hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fourteen patients with HCC >5 cm in diameter received surgical or percutaneous microwave ablation with more than 12 months of follow-up. Microwave ablation was performed using a 902-928 MHz generator at 28 W; a single 14 G antenna without water-cooled system was used. The patients were followed up with contrast-enhanced CT and serum alpha-foetoprotein to monitor for tumour recurrence at 1 month and then every 3 months after tumour ablation. RESULTS: The follow-up duration for the 11 male and three female patients (mean tumour size 5.77 cm, range 5-7 cm; mean age 63.8 years) was 15.8 months. The mean ablation time was 2025 s (range 900-3600 s), and the mean ablation session was 2.5 (range 1-4). The complete ablation rate was 85% (17 of 20). Local recurrence rate was 5.8% (1 of 17). All patients survived and the morbidity and mortality rate was 21.4% and 0%, respectively. CONCLUSIONS: Microwave tissue ablation using this novel system with tissue permittivity feedback control and a single uncooled antenna has a high complete ablation rate and lower morbidity. It proved to be a fast, easy, and effective option for ablation of large (>5 cm) tumours.

Hepatic necro-inflammation and elevated liver enzymes: evaluation with MRI perfusion imaging with gadoxetic acid in chronic hepatitis patients.

AIM: To evaluate liver necro-inflammation and function by using gadoxetic acid-enhanced dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), with histological analysis as the reference standard. MATERIALS AND METHODS: Seventy-nine subjects (21 healthy subjects; 58 chronic hepatitis patients) who received gadoxetic acid-enhanced DCE-MRI were divided into three subgroups: no (A0, n = 31), mild (A1, n = 27), and moderate-severe (A2-A3, n = 21) activities. Two DCE-MRI models were measured: (1) a dual-input single-compartment model to obtain absolute arterial, portal venous, and total blood flow, arterial fraction (ART), distribution volume, and mean transit time; (2) a curve analysis method to obtain peak, slope, and AUC (area under curve). The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels also obtained. Statistical testing included Kruskal-Wallis tests for continuous data, Pearson's correlation tests, and multiple linear regression analyses. RESULTS: Hepatic necro-inflammatory activity grades were significantly correlated with fibrotic stages, serum ALT level, ART and AUC. ART was helpful to predict the mild activity (≤ A1 versus >A1; Az = 0.728), whereas AUC could differentiate no activity from any activity (A0 versus >A0; Az = 0.703). Peak, slope and AUC were all associated with AST and ALT (p < 0.05). CONCLUSION: Gadoxetic acid-enhanced DCE-MRI parameters may be used to evaluate the severity of hepatic necro-inflammation and function.

Effects of tendon viscoelasticity in Achilles tendinosis on explosive performance and clinical severity in athletes.

The aim was to compare viscoelastic properties of Achilles tendons between legs in elite athletes with unilateral tendinosis, and to investigate relationships between the properties and explosive performance and clinical severity. Seventeen male athletes (mean ± standard deviation age, 27.3 ± 2.0 years) who had unilateral, chronic middle-portion tendinopathy of the Achilles tendon were assessed by the Victorian Institute of Sport Assessment questionnaire, measurements of tendon viscoelastic properties, voluntary electromechanical delay (EMD), normalized rate of force development (RFD), and one-leg hopping distance. Compared with the non-injured leg, the tendinopathic leg showed reduced tendon stiffness (-19.2%. P < 0.001), greater mechanical hysteresis (+21.2%, P = 0.004), lower elastic energy storage and release (-14.2%, P = 0.002 and -19.1%, P < 0.001), lower normalized RFD at one-fourth (-16.3%, P = 0.02), 2/4 (-17.3%, P = 0.006), and three-fourths maximal voluntary contraction (-13.7%, P = 0.02), longer soleus and medial gastrocnemius voluntary EMD (+26.9%, P = 0.009 and +24.0%, P = 0.004), and shorter hopping distances (-34.1%, P < 0.001). Tendon stiffness was correlated with normalized RFD, voluntary EMD in the medial gastrocnemius, and hopping distances (r ranged from -0.35 to 0.64, P < 0.05). Hysteresis was correlated to the soleus voluntary EMD and hopping distances (r = 0.42 and -0.39, P < 0.05). We concluded that altered tendon viscoelastic properties in Achilles tendinosis affect explosive performance in athletes.

Relationships between three potentiation effects of plyometric training and performance.

UNLABELLED: This study measured the potentiation effects of plyometric training [normalized electromyography (EMG) in triceps surae, stiffness and elastic energy utilization of the Achilles tendon] and investigated the correlations between these effects and performances [voluntary electromechanical delay (EMD) and jump height]. Twenty-one subjects were randomly assigned either to the control group (10 subjects: age 22.3+/-1.6 years) or to a training group (11 subjects: age 22.1+/-1.6 years) that performed 8 weeks of plyometric training. RESULTS: As compared with the performances before training, normalized EMG in the soleus were significantly (P

Vertebral osteonecrosis: MR imaging findings and related changes on adjacent levels.

BACKGROUND AND PURPOSE: No prior report has comprehensively discussed the intravertebral vacuum cleft sign and the fluid sign on MR images of vertebral osteonecrosis. The purpose of this study was to investigate MR images of osteonecrotic vertebral bodies and adjacent intervertebral disks and vertebral bodies. METHODS: We retrospectively reviewed MR images of patients with vertebral osteonecrosis. Affected vertebral bodies with osteonecrosis were defined as an avascular area (nonenhanced area on enhanced T1-weighted images) with collections of intravertebral fluid (hyperintense signal on T2-weighted images), air (signal void on all images), or both. The degree of vertebral collapse was classified as mild (>50%) or severe (<50%) preserved vertebral height. Changes in adjacent intervertebral disks or vertebral bodies 2 above and 2 below the affected vertebrae were compared. RESULTS: We enrolled 112 patients (30 men, 82 women; 121 vertebral bodies) in our study. Intravertebral air alone was observed in 48 involved levels (39.7%), intravertebral fluid alone was found in 47 (38.8%), and both coexisted in 26 (21.5%). Degree of vertebral collapse in affected vertebral bodies significantly differed with presence of air or fluid (P < .05). Vertebral compression fractures adjacent to the affected vertebral bodies were more common in those with intravertebral air alone than in those with intravertebral fluid alone (P < .05). CONCLUSION: Vertebral collapse was more advanced and adjacent vertebral compression fractures were more frequent in patients with intravertebral air than in those with intravertebral fluid.

In vivo kinematic study of normal wrist motion: an ultrafast computed tomographic study.

OBJECTIVE: To quantify in vivo carpal kinematics of a normal wrist in a dynamic continuous model. DESIGN: The instantaneous changes in the radiocarpal and midcarpal joints during normal wrist motion were analyzed using ultrafast computed tomography (CT). BACKGROUND: Wrist injuries account for a considerable and growing proportion of work-related disorders and disability. However, little is known about normal wrist kinematics. METHODS: Ten uninjured subjects were studied using ultrafast CT to measure the continuous motion of the wrist from full flexion to full extension. Sagittal plane scanning was performed mediolaterally at six different locations as the wrists were moved slowly and repeatedly from full flexion to full extension. The data were printed to X-ray film and transferred to an independent work station with a video camera. The motion of the radiocarpal, midcarpal and wrist joints was determined by an image analyzing system. RESULTS: Wrist motion was expressed as a ratio of capitate-lunate (C-L) (midcarpal) motion and radio-lunate (R-L) (radiocarpal) motion. In the volar flexion of normal wrists, the contribution of the radiocarpal joint and midcarpal joint were approximately equal; while dorsal flexion of the normal wrist occurred mainly at the midcarpal joint. CONCLUSIONS: In normal wrists, the radiocarpal joint and midcarpal joint contribute equally to volar flexion, while the midcarpal joint is more important in dorsal flexion. RELEVANCE: In this study, we demonstrated the suitability of using two-dimensional computed tomographic images in a quantitative study of flexion/extension kinematics of the normal wrist.

The evaluation of false negative mammography from malignant and benign breast lesions.

Preoperative mammograms from 395 breast cancers and 132 benign breast lesions were enrolled for this study. The false-negative (FN) rate for breast cancers from preoperative reading was 9.6% with 38 breast cancers missed on mammograms. The statistically significant differences occurred between true-positive (TP) and FN cancers for younger age (P<.025), smaller lesion size (P<.001), denser breast (P<.05), deep retroglandular location (P<.001). None of the FN cancers exhibited calcifications. The FN rate for mammography for benign breast lesions from preoperative reading was 18.9% with 25 lesions misdiagnosed. The statistically significant difference between benign TP and FN lesions occurred for central and subareolar location (P<.025). Exploration of possible factors and imaging features in FN mammograms can help reduce the FN rate for mammography.

Early diagnosis of single segment vertebral osteomyelitis--MR pattern and its characteristics.

Nine cases of single segment vertebral osteomyelitis were included based on the single level of vertebral body involvement according to the MR findings. They were 3 cases with tuberculous infection and 6 cases with pyogenic infection. The vertebral body involvement was presented as abnormal signal changes (100%) and heterogenous enhancement (77.7%). They usually caused the cortical disruption in its anterior aspect (100%). It goes along the upward subligamentous spread (100%) most often, then the upper disc involvement (66.6%) and downward subligamentous spread (55.5%). The lower disc involvement is least common (11.1%). By using these criteria, the single segment vertebral osteomyelitis could be earlier diagnosed.

Bilateral elastofibroma dorsi. Two case reports.

Elastofibroma dorsi is a benign fibroproliferative lesion of unknown pathogenesis. It is most commonly found in the periscapular region in elderly women. The majority of patients are asymptomatic. The lesions have a characteristic location and a specific magnetic resonance imaging (MRI) appearance allowing accurate prospective diagnosis. The importance of recognizing the benign nature of this lesion to avoid an unnecessary operation is apparent. We describe two cases of bilateral elastofibroma dorsi with characteristic findings on MRI and typical histological appearances.

Correlation between MRI and operative findings of the rotator cuff tear.

Rotator cuff disease is one of the most common causes of shoulder pain. Various methods have been used to evaluate this problem. In this study, we determine the accuracy of magnetic resonance imaging (MRI) of the shoulder in diagnosing the rotator cuff tear based on operative findings. Ten patients with a painful shoulder requiring operation received an MRI of the shoulder before surgery. A GE 1.5 Tesla MR scanner with a five-inch planar surface coil was applied and the diagnosis was confirmed by an experienced radiologist in the field of musculoskeletal MRI. All patients underwent surgery within two weeks of MRI examination. Nine of the 10 patients were shown to have rotator cuff tear by MRI. Among the nine MRI positive patients, eight were proven to have such lesions on operation (two massive tears, four moderate complete tears, and two bursal side tears). One false-positive result was found to be an adhesive capsulitis and supraspinatus tendinitis at operation. The remaining case, diagnosed as tendinitis by MRI, turned out to be a small incomplete tear on operation. Therefore, the sensitivity of MRI for rotator cuff tear in this study was 0.89. The overall accuracy was 80%. We concluded that MRI has a high accuracy in detecting the rotator cuff tear. False-positive and false-negative diagnoses were attributed to a severe tendinitis and an incomplete tear, respectively.

Diagnosis of cardiac metastasis by computed tomography: report of 5 cases.

Five patients with underlying malignancy were detected antemortemly to have cardiac metastasis by post-enhanced CT scanning. The most common presentations were abnormal heart sounds, electrocardiographic changes and inexplicable heart failure; which lead us to suspect cardiac metastasis. One patient had an "engorged azygous knob" on his chest x-ray film, which provided a clue to possible cardiac metastasis. All of these patients had tumor thrombi in their large tributary veins in addition to the primary tumors. Thus, we advanced the CT scan to the cardiac region and cardiac metastases were, therefore, diagnosed. The tumor thrombi in the large tributary veins seemed to be the source for intracardiac spreading. Cardiac angiographies were performed in 3 patients and confirmed the diagnosis. We conclude that post-enhanced CT scanning is useful in the diagnosis of cardiac metastasis and the presence of tumor thrombi in the large tributary vein is an early sign of cardiac involvement.

Multiplanar gradient recalled images of the knee: comparison of different flip angles and echo times.

To determine the most appropriate combination of echo time (TE) and flip angle in gradient echo images of the knee, the authors used different TEs (10, 20 and 30 msec) and flip angles (10, 30, 50, 70, 90, 120 and 150 degrees) to perform a systematic study of MRI on 10 volunteer knees. Contrast-to-noise ratios of cartilage-fat, fluid-cartilage, fluid-fat and fluid-ligament were calculated and compared. Images with a 30-degree flip angle combined with 20 msec of TE were found to have the best contrast-to-noise ratios in both objective data analysis and subjective observation. Hyaline cartilage of the knee was hyperintense and was well delineated on this pulse sequence, appearing distinct in contrast to the intra-articular fluid. It is concluded that this T2-weighted gradient echo pulse sequence is an alternative to conventional spin echo T2-weighted imaging of the knee.

Magnetic resonance imaging of vertebral compression fractures.

In this study, magnetic resonance imaging (MRI) was used to analyze the signal intensity and vascularity of compression fractures of vertebrae in 74 patients. The possibility of nonunion was assessed according to the specific image findings and clinical presentation. All patients had chronic back pain for more than 3 months and compression fractures of the vertebrae initially demonstrated by plain radiography. Pre-enhanced T1 and T2*-weighted images (*multiplaner gradient recall sequence) and postenhanced MRI were obtained. Images were divided into three categories according to the signal intensity of the fractured vertebrae such as hyperintensity (n = 35), hypointensity (n = 24) on T1-weighted image and necrotic type compression fractures of the vertebrae (n = 15). Of the 15 necrotic-type cases, 13 disclosed "fluid"-containing space at the collapsed vertebrae and two showed "air"-containing space at the vertebral body. We believe that these findings are pathognomonic signs of nonunion of the collapsed vertebrae. Surgical specimens were obtained from the four patients whose vertebrae showed necrosis and granulation tissue. After posterior spinal instrumentation, the collapsed vertebral body regained the height and presence of the open end-plate of the vertebra on postoperative lateral radiography. The superior capabilities of MRI offers useful criteria that make the diagnosis of nonunion in compression fractures of the spine possible. Thus, a space with "fluid" or "air" collection at the anterior aspect of a collapsed vertebra as well as strong enhancement with Gd-DTPA at the posterior aspect of the collapsed vertebra may be considered to be pathognomonic signs of nonunion of the fractured vertebra.

MRI of meniscus and cruciate ligament tears correlated with arthroscopy.

Findings from magnetic resonance imaging (MRI) studies of 50 knees were retrospectively interpreted. The results were correlated with arthroscopic findings. Multiple pulse sequences were performed including sagittal double-echo, coronal T1-weighted and gradient echo, axial gradient echo or fat suppression imaging. Three-dimensional MRI was performed if there was a high suspicion of a tear of the anterior cruciate ligament. The individual positive predictive value, sensitivity, specificity and accuracy were calculated from the comparison between MRI and arthroscopic findings of the menisci, anterior cruciate ligament and posterior cruciate ligament. The following results were obtained: 1) Tears of the medial meniscus-positive predictive value, 72%; sensitivity, 87%; specificity, 86%; and accuracy, 86%. 2) Tears of the lateral meniscus-positive predictive value, 85%; sensitivity, 85%; specificity, 90%; and accuracy, 88%. 3) Tears of the anterior cruciate ligament-positive predictive value, 88%; sensitivity, 95%; specificity, 89%; and accuracy, 92%. 4) Tears of the posterior cruciate ligament-positive predictive value, 100%; sensitivity, 100%; specificity, 100%; and accuracy, 100%. It is concluded that MRI is a noninvasive and accurate method for detecting the internal derangement of the knee.

Infectious spondylitis: MRI characteristics.

Magnetic resonance imaging (MRI) scans of 24 patients with clinically proven infectious spondylitis were retrospectively evaluated. Evaluation was made of abnormal signal and enhancement patterns within vertebral bodies, intervening disks, and epidural and paraspinal abscesses. The causative organisms included Mycobacterium tuberculosis, fungi and pyogenic bacteria. Staphylococcus aureus was the predominant causative organism among pyogentic bacteria. Decreased signal intensity of vertebral marrow on T1-weighted images was more extensive in pyogenic infections. Multilevel involvement (more than two) was observed in six of the 24 patients. Contiguous multilevel involvement was observed only in patients with tuberculous spondylitis. Noninvolvement of the intervertebral disk space was observed in two patients with pyogenic spondylitis. Epidural abscess was found in 15 patients, most of whom had dense, homogeneous enhancement. Paraspinal abscess was found in 18 patients. Diffuse patchy enhancement without obvious abscess formation in the paraspinal compartment was found in those patients with pyogenic infections. "Rice bodies" were found in paraspinal abscesses in only three patients with tuberculous spondylitis. It was difficult to differentiate candidal from tuberculous spondylitis on MRI. Compared with pyogenic infection, tuberculous spondylitis had a predilection for spinal deformity, subligamentous spread, contiguous multilevel involvement, presence of signal voids in paraspinal abscesses on T2WT and a lesser extent of marrow edema.

Malignant chondroid syringoma.

A case of malignant chondroid syringoma on a foot with multiple bone metastases is presented. An 18-year-old male patient first noticed a protruding mass on the plantar surface of his right foot at 9 years of age. A sweat gland tumor of a benign nature was diagnosed and excised at that time. The tumor recurred three times during the 10 years after surgery and was finally diagnosed as malignant chondroid syringoma. Multiple bone metastases involving the calcaneus, talus and fibula of the lesion side were found after extensive radiologic survey. The patient underwent below-knee amputation with total removal of the fibula. However, pelvic bone metastasis developed 1 year after the amputation. He died of this disease due to brain and diffuse bony metastasis 36 months after the amputation. This is a rare case of malignant chondroid syringoma with a long history but ominous outcome. We recommend that sweat gland tumors be carefully examined and treated more radically when there is a suspicion of malignancy.

Magnetic resonance imaging in patients with hemodialysis-related arthropathy.

From April 1993 to December 1993, we prospectively studied the knees of 15 patients (mean age, 48 +/- 11 yr) receiving long-term hemodialysis (mean duration, 9 +/- 4 yr) using magnetic resonance imaging (MRI) techniques including, T1 weighted spin-echo, multiplanar gradient recalled, and postcontrast T1 with chemical shift-selective, fat-saturation pulse sequences. Analysis of these images revealed that the three findings most indicative of hemodialysis-related arthropathy were intramedullary, cortical and soft tissue lesions. Knee pain was significantly correlated with the presence of soft tissue lesions. Cortical lesions were usually associated with soft tissue lesions. Inflammatory changes adjacent to soft tissue lesions were demonstrated in postcontrast studies in all patients with soft tissue lesions. Increases in water content in those lesions appeared to increase the signal intensity. Our results indicate that MRI is useful in demonstrating the extent of hemodialysis-related arthropathy involvement, especially in hemodialysis patients suffering from knee pain.

Magnetic resonance imaging of rotator cuff lesions.

The purpose of this study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) in rotator cuff diseases. Forty consecutive patients studied by MRI from September 1990 to September 1992 were included in the study. MRI was performed on a 1.5 tesla MR scanner. Each MRI study was reviewed by two radiologists experienced in rotator cuff tendons. The MRI finding was compared with the surgical result. MRI sensitivity for all tears (partial and complete) was 1.0 (22/22), specificity 0.89 (16/18), accuracy rate 0.95 (38/40), and the predictive value 0.92 (22/24). Signal changes of the rotator cuff tendon (primary signs) were the most reliable criteria in diagnosis of the tear. Changes of subacromial and subdeltoid fat planes and bursa (secondary signs) were complimentary when primary signs were indeterminant. The direction of the long axis of abnormal signal intensity in the rotator cuff tendon may be a good indicator when differentiating tears from tendinitis. We conclude that MRI shows excellent performance in the determination of the presence or absence of a rotator cuff tear.

Paget's disease of the bone: a case report.

Paget's disease of bone is rare in Asia. We report a case of Paget's disease in a 58-year-old Taiwanese man who was admitted with a 3-month history of bilateral numbness in the buttock region. Laboratory data disclosed an elevated serum alkaline phosphatase level (510 U/L). Plain radiographs of the lumbar spine showed generalized increased density at the third lumbar vertebra, associated with cortical thickening, loss of cortico-cancellous definition, and increased anteroposterior diameter. The T1-weighted magnetic resonance image of the lumbar spine showed diffuse, heterogeneous low signal intensity at the third lumbar vertebral body, pedicle, laminae, and spinal process; these areas showed mixed high and low signal intensity on the T2-weighted image. Technetium-99m bone scan revealed abnormal uptake in the involved vertebra. Histologic examination of the third lumbar spinal process confirmed the diagnosis of Paget's disease of bone. The patient remained well during a follow-up period of 6 months.

Evaluation of hip disorders by radiography, radionuclide scanning and magnetic resonance imaging.

Thirty-six hips were studied because of significant hip pain. Radiography of the hip and bone scintigraphy showed subtle changes. Magnetic resonance imaging (MRI) was performed using a 1.5 Tesla superconductive unit. All MRI findings were confirmed by surgical or pathologic results. Twenty-nine hips had a single lesion, including: infection (one), fracture (eight), avascular necrosis of the femur(two), or contralateral hip (four), transient osteoporosis (six), osteoporosis (one), post-irradiation myositis (one), metastasis (four), and synovitis (two). Twenty-six lesions (89.6%) appeared normal on the radiographs of the hip, while three lesions (10.4%) showed only osteoporotic change. Another seven hips had more than one lesion, including: avascular necrosis and fracture (four), fracture foci (two), and metastasis and fracture (two). Radiography of the hip showed either a negative finding or detected only a single lesion, missing other important pathologic foci. MRI is extremely sensitive to alterations in the bone marrow that may represent pathology occult to plain radiography and bone scintigraphy of the hips. For diagnosis and treatment planning, MRI of the hips should be performed early in patients with persistent pain and negative radiography findings.