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.

Recurrent syncope due to refractory cerebral venous sinus thrombosis and transient elevations of intracranial pressure.

Chronic paroxysmal intracranial hypertension leading to syncope is a phenomenon not reported previously in patients with refractory cerebral venous sinus thrombosis. We report a case of paroxysmal intracranial hypertension leading to syncopal episodes in a patient with idiopathic autoimmune hemolytic anemia and venous sinus thrombosis. This case demonstrates that intermittent elevations in intracranial pressure can lead to syncope in patients with venous sinus thrombosis and emphasizes the importance of considering this potentially treatable etiology of syncopal episodes.

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.

Thigh muscle volume predicted by anthropometric measurements and correlated with physical function in the older adults.

OBJECTIVES: (1) to correlate thigh muscle volume measured by magnetic resonance image (MRI) with anthropometric measurements and physical function in elderly subjects; (2) to predict MRI-measured thigh muscle volume using anthropometric measurements and physical functional status in elderly subjects. DESIGN: Cross-sectional, nonrandomized study. SETTING: Outpatient clinic in Taiwan. PARTICIPANTS: Sixty-nine elderly subjects (33 men and 36 women) aged 65 and older. MEASURMENTS: The anthropometric data (including body height, body weight, waist size, and thigh circumference), physical activity and function (including grip strength, bilateral quadriceps muscle power, the up and go test, chair rise, and five meters walk time) and bioelectrical impedance analysis data (including total body fat mass, fat-free mass, and predictive muscle size) were measured. MRI-measured muscle volume of both thighs was used as the reference standard. RESULTS: The MRI-measured thigh volume was positively correlated with all anthropometric data, quadriceps muscle power and the up and go test as well as fat-free mass and predictive muscle mass, whereas it was negatively associated with age and walk time. In predicting thigh muscle volume, the variables of age, gender, body weight, and thigh circumference were significant predictors in the linear regression model: Muscle volume (cm3) =4226.3－42.5 × Age (year)－955.7 × gender (male=1, female=2) + 45.9 × body weight(kg) + 60.0 × thigh circumference (cm) (r2 = 0.745, P < 0.001; standard error of the estimate = 581.6 cm3). CONCLUSION: The current work provides evidence of a strong relationship between thigh muscle volume and physical function in the elderly. We also developed a prediction equation model using anthropometric measurements. This model is a simple and noninvasive method for everyday clinical practice and follow-up.

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

Unusual manifestations of vertebral osteomyelitis: intraosseous lesions mimicking metastases.

BACKGROUND AND PURPOSE: Vertebral osteomyelitis can have different imaging manifestations. The purpose of this study was to demonstrate the unusual MR imaging patterns of vertebral osteomyelitis with intraosseous lesions mimicking metastases. MATERIALS AND METHODS: From September 2000 to August 2007, 7 patients were selected from our data base of 214 patients with confirmed vertebral osteomyelitis and MR images. All of those having misinterpreted MR imaging reports and unusual imaging patterns were analyzed. The presence of a peripheral curvilinear area of low signal intensity in an osseous lesion (the rim sign) and a peripheral rim of high signal intensity on T2-weighted images around an osseous lesion (the halo sign) was evaluated. Follow-up MR imaging studies were performed in all patients. RESULTS: The patients were 5 men and 2 women, with an age range of 42-80 years. MR imaging findings of those with vertebral osteomyelitis showed a solitary lesion in 2 and multiple lesions in 5 patients. The intraosseous lesions revealed low signal intensity on T1-weighted images, mixed or high signal intensity on T2-weighted images, high signal intensity on short tau inversion recovery images, and global or marginal enhancement. The rim sign was found in 6 (86%) patients; halo sign, in 7 (100%); preserved intervertebral disks, in 7 (100%); and limited paraspinal or epidural inflammation, in 6 (86%). Images of all patients demonstrated healing or almost healed changes on the follow-up MR imaging studies. CONCLUSION: Vertebral osteomyelitis can have MR imaging patterns mimicking osseous metastases. Recognition of these unusual imaging manifestations, together with clinical and histopathologic analysis, may aid in reaching the correct diagnosis.

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.

Partial and complete tear of the anterior cruciate ligament.

PURPOSE: To analyze MR direct and indirect signs for knees with anterior cruciate ligament (ACL) partial or complete tear. MATERIAL AND METHODS: According to documented MR direct and indirect signs for ACL tear, we retrospectively reviewed the incidence of those signs in 15 partial ACL tear and 17 complete ACL tear patients. The findings were also compared with duration of injury (less or more than 6 weeks, as acute or chronic stages). RESULTS: A residual straight and tight ACL fiber in at least one pulse sequence was more frequently detected in partial ACL tears. The empty notch sign, a wavy contour of ACL, bone contusion at lateral compartment and lateral meniscus posterior horn tear were significantly more frequently seen in complete tear cases. The posterior cruciate ligament angle in chronic complete ACL tear cases (109 degrees +/-20 degrees ) had a tendency to be less than in chronic partial ACL tear cases (119+/-18 degrees ). CONCLUSION: The empty notch sign, a wavy ACL, bone contusion, and posterior horn of lateral meniscus tears are suggestive of a complete ACL tear. A residual straight and tight ACL fiber seen in at least one image section is a helpful sign to diagnosis of partial ACL tear. In the acute ACL injury stage, a focal increase of the ACL signal intensity is more suggestive of a partial ACL tear.

Tophaceous gout of the spine: MR imaging features.

AIM: To define the magnetic resonance (MR) imaging features of tophaceous gout of the spine. MATERIALS AND METHODS: We present the MR imaging examinations of 4 patients with spinal tophaceous gout. Spin-echo T1-weighted and fast spin-echo T2-weighted images were obtained for all patients, and 2 patients had gadolinium-enhanced MR imaging studies. Corresponding computed tomography (CT) was performed in one patient. All images were evaluated for the characteristics of the gouty tophi. RESULTS: The gouty tophi were located at the lower thoracic (n=1) and lumbar (n=3) levels. All tophi yielded homogeneous intermediate to low signal on T1-weighted images and variable signal intensity on T2-weighted images, comprising small foci of very low signal intensity on all sequences. Gadolinium-enhanced MR imaging studies revealed homogeneous enhancement or heterogeneous peripheral enhancement. Diffuse stippled calcifications were found in the tophi on CT images. Periarticular tophi with juxtaarticular bony erosions around facet joints occurred in 3 patients. CONCLUSION: Spinal tophaceous gout should be considered in the differential diagnosis when periarticular deposits contain very low signal foci on all MR imaging sequences.

MR imaging of displaced meniscal tears of the knee. Importance of a "disproportional posterior horn sign".

PURPOSE: Meniscal tears associated with displaced fragments are clinically significant. We propose the "disproportional posterior horn sign" as a supportive criterion to identify a posterocentrally displaced meniscal fragment on MR imaging studies. If the meniscal posterior horn in the central portion appears larger than that in the peripheral section, it is considered positive for "disproportional posterior horn sign". MATERIAL AND METHODS: MR images obtained in 42 patients with 43 lesions, confirmed to have displaced meniscal tears, were included in this study. The MR images were retrospectively evaluated for the presence of the "disproportional posterior horn sign", as well as the other known signs. RESULTS: The "disproportional posterior horn sign" was seen in 9 (20.9%) of 43 lesions, including 1 lateral discoid meniscal tear, 5 lateral meniscal tears and 3 medial meniscal tears. Five of them also had other signs of a displaced meniscal fragment. However, the remaining 4 cases only exhibited the "disproportional posterior horn sign". For the other MR signs, the "absent bow tie sign" was detected in 40 (93%) of 43 lesions, the "flipped meniscus sign" in 27 (62.8%) of 43 lesions, the "double posterior cruciate ligament sign" in 17 (39.5%) of 43 lesions and the "notch fragment sign" in 22 (51.2%) of 43 lesions. CONCLUSION: The "disproportional posterior horn sign" is helpful in demonstrating a posterocentrally displaced meniscal fragment, especially when other characteristic signs are unremarkable or absent.

Vertebral bone marrow perfusion evaluated with dynamic contrast-enhanced MR imaging: significance of aging and sex.

PURPOSE: To investigate blood perfusion of nonfractured, normal-appearing vertebral bodies with regard to age and sex. MATERIALS AND METHODS: Dynamic magnetic resonance imaging (160 images obtained in 80 seconds) was performed from T10 to L5 in 66 patients. Patients were assigned to three groups: group 1, those 50 years or younger without compression fracture; group 2, those older than 50 years without compression fracture; or group 3, those older than 50 years with compression fracture. Peak enhancement percentage and enhancement slope were determined from the time-intensity curve of normal (nonfractured) vertebral body. Comparisons were made between groups, and the effect of age and sex interaction was analyzed. RESULTS: Higher peak enhancement percentage was demonstrated for group 1 compared with group 2 (58.21 +/- 44.65 [SD] vs 21.88 +/- 14.77, P <.005). Group 1 women revealed a higher enhancement percentage compared with group 1 men (87.17 +/- 54.13 vs 38.16 +/- 21.69, P <.05), which significantly decreased in those older than 50 years (from 87.17 +/- 54.13 to 17.98 +/- 13.80, P <.005). For men, this decrease in those older than 50 years was not as pronounced (from 38.16 +/- 21.69 to 25.38 +/- 15.43, P >.05). Presence of compression fracture at other levels of the spine (group 3) was not associated with a different enhancement percentage for normal vertebrae. CONCLUSION: Rate of vertebral bone marrow perfusion revealed a significant decrease in subjects older than 50 years. Women demonstrated a higher marrow perfusion rate than men younger than 50 years and a more marked decrease than men older than 50 years.

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.

Spinal fractures and pseudoarthrosis complicating ankylosing spondylitis: MRI manifestation and clinical significance.

PURPOSE: To analyze magnetic resonance (MR) patterns of fractures and pseudoarthrosis of the ankylosing spondylitic spine, and related changes in the dura and adjacent soft tissue. MATERIALS AND METHODS: Sixteen patients with radiographically evident fractures or pseudoarthrosis of the spine were included. Each underwent MR studies. Ten patients among them underwent surgical operations. RESULTS: Both transdiscal (n = 12) and transvertebral (n = 4) fractures were identified. The levels were located from T9 to L3. Five of 16 patients had pseudoarthrosis. The fractures or pseudoarthrosis had two patterns: low signal on T1-and high signal on T2-weighted images, and low signal on both T1-and T2-weighted images. Disruption of anterior longitudinal ligament (ALL) was identified in 14 patients. Seven patients had vertebral translation, all had disruption of the ALL. Dural adhesions were noted in five patients and manifested as linear epidural enhancements with triangular blunt edges. CONCLUSION: MR patterns of ankylosing spondylitis are important in evaluating complications of fractures or pseudoarthrosis, as well as changes in dura, soft tissue, and ligaments.

Sequence influence of nonidentical InGaAsP quantum wells on broadband characteristics of semiconductor optical amplifiers--superluminescent diodes.

Extremely broadband emission is obtained from semiconductor optical amplifiers-superluminescent diodes with nonidentical quantum wells made of InGaAsP/InP materials. The well sequence is experimentally shown to have a significant influence on the emission spectra. With the three In(0.67) Ga(0.33) As(0.72) P(0.28) quantum wells near the n -cladding layer and the two In(0.53) Ga(0.47) As quantum wells near the p -cladding layer, all bounded by In(0.86) Ga(0.14) As(0.3)P(0.7) barriers, the emission spectrum could cover from less than 1.3 to nearly 1.55 microm, and the FWHM could be near 300 nm.

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.

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.

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.

Solitary vertebral collapse: distinction between benign and malignant causes using MR patterns.

Differentiation of benign from malignant causes of vertebral compression fracture can be difficult at a single location. We studied 37 patients with solitary vertebral collapse (SVC) in the spine using magnetic resonance imaging (MRI). Sixteen of them were found to have a benign cause of SVC, while the remaining 21 were found to have malignancy. The following four MRI characteristics were investigated: ill- or well-defined margin of the intravertebral lesion (P < 0.005); pedicle involvement (P < 0.05); MR enhancement pattern (P < 0.005); and paravertebral soft tissue lesion (PSL) (P < 0.025). It was found that cases of malignant SVC tended to have an ill-defined margin, abnormal signal involvement of the pedicle, a marked and heterogenous MR enhancement pattern, and irregular nodular-type PSL. Pedicle change with expansile lesion totally excluded a benign cause. By using these criteria, we were able to differentiate benign or malignant causes of SVC accurately.