Development of a new phantom simulating extracellular space of tumor cell growth and cell edema for diffusion-weighted magnetic resonance imaging.

OBJECTIVE: A phantom for diffusion-weighted imaging is required to standardize quantitative evaluation. The objectives were to develop a phantom simulating various cell densities and to evaluate repeatability. MATERIALS AND METHODS: The acrylic fine particles with three different diameters were used to simulate human cells. Four-degree cell density components were developed by adjusting the volume of 10-µm particles (5, 20, 35, and 50% volume, respectively). Two-degree components to simulate cell edema were also developed by adjusting the diameter without changing number (17% and 40% volume, respectively). Spearman's rank correlation coefficient was used to find a significant correlation between apparent diffusion coefficient (ADC) and particle density. Coefficient of variation (CV) for ADC was calculated for each component for 6 months. A p value < 0.05 represented a statistically significance. RESULTS: Each component (particle ratio of 5, 17, 20, 35, 40, and 50% volume, respectively) presented ADC values of 1.42, 1.30, 1.30, 1.12, 1.09, and 0.89 (× 10-3 mm2/s), respectively. A negative correlation (r = - 0.986, p < 0.05) was observed between ADC values and particle ratio. CV for ADC was less than 5%. DISCUSSION: A phantom simulating the diffusion restriction correlating with cell density and size could be developed.

Correction to: Development of a new phantom simulating extracellular space of tumor cell growth and cell edema for diffusion-weighted magnetic resonance imaging.

The original version of this article unfortunately contained a mistake. Second column of "Cell edema" should read as.

The reproducibility of measurements using a standardization phantom for the evaluation of fractional anisotropy (FA) derived from diffusion tensor imaging (DTI).

OBJECTIVES: It is necessary to standardize the examination procedure and diagnostic criteria of diffusion tensor imaging (DTI). Thus, the purpose of this study was to examine the reproducibility of measurements using a standardization phantom composed of different fibre materials with different fibre densities (FDs) for the evaluation of fractional anisotropy (FA) derived from DTI. MATERIALS AND METHODS: Two types of fibre materials wrapped in heat-shrinkable tubes were used as fibre phantoms. We designed fibre phantoms with three different FDs of each fibre material. The standardization phantom was examined using DTI protocol six times a day, and each examination session was repeated once a month for 7 consecutive months. Fibre tracking was performed by setting regions of interest in the FA map, and FA was measured in each fibre phantom. Coefficients of variation (CVs) were used to evaluate the inter-examination reproducibility of FA values. Furthermore, Bland-Altman plots were used to evaluate the intra-operator reproducibility of FA measurements. RESULTS: All CVs for each fibre phantom were within 2% throughout the 7-month study of repeated DTI sessions. The high intra-operator reproducibility of the FA measurement was confirmed. DISCUSSION: High reproducibility of measurements using a standardization phantom for the evaluation of FA was achieved.

[Improvement of Image Quality in the Axial Section Using High-resolution Scan Mode and Hybrid Iterative Reconstruction in Ultra-high-resolution Computed Tomography].

The purpose of this study is to compare the physical characteristics and visibility of high-resolution and conventional images acquired with the same X-ray dose, and to investigate the superiority of super high-resolution imaging. A Catphan phantom was scanned in the normal resolution (NR), high-resolution (HR), and super high-resolution (SHR) modes of ultra-high-resolution computed tomography at 120 kV and 75 mAs. All images were reconstructed into a 5-mm thick image slices with filtered back-projection (FBP) and hybrid image reconstruction (HIR), which included normal and enhanced adaptive iterative dose reduction 3D (AIDR and eAIDR, respectively). The modulation transfer function (MTF) and noise power spectrum (NPS) were measured using the circular edge method and radial frequency method, respectively. The signal-to-noise ratio (SNR) was then calculated. High-contrast resolution and low-contrast detectability were evaluated visually by five radiological technologists. The MTFs of HReAIDR and HRFBP images were higher than those of NRFBP images. However, the NPSs of HReAIDR and HRFBP images were larger than those of NRFBP images. The SNR of HReAIDR images was higher than that of NRFBP and HRFBP images. The scores of high-contrast resolution of HReAIDR, NRFBP, and HRFBP images were 13, 8, and 13 cycles/cm, respectively, and the scores of low-contrast detectability were 5, 5, and 6 mm, respectively. Hence, an improvement in high-contrast resolution of signal more than 400 HU in the axial section can be achieved without increasing the radiation dose and decreasing low-contrast detectability with 10 HU using the HR mode and eAIDR.

RAD-Seq analysis of typical and minor Citrus accessions, including Bhutanese varieties.

We analyzed the reduced-representation genome sequences of Citrus species by double-digest restriction site-associated DNA sequencing (ddRAD-Seq) using 44 accessions, including typical and minor accessions, such as Bhutanese varieties. The results of this analysis using typical accessions were consistent with previous reports that citron, papeda, pummelo, and mandarin are ancestral species, and that most Citrus species are derivatives or hybrids of these four species. Citrus varieties often reproduce asexually and heterozygosity is highly conserved within each variety. Because this approach could readily detect conservation of heterozygosity, it was able to discriminate citrus varieties such as satsuma mandarin from closely related species. Thus, this method provides an inexpensive way to protect citrus varieties from unintended introduction and to prevent the provision of incorrect nursery stocks to customers. One Citrus variety in Bhutan was morphologically similar to Mexican lime and was designated as Himalayan lime. The current analysis confirmed the previous proposition that Mexican lime is a hybrid between papeda and citron, and also suggested that Himalayan lime is a probable hybrid between mandarin and citron. In addition to Himalayan lime, current analysis suggested that several accessions were formed by previously undescribed combinations.

[Verification of the dose from an iridium-192 ((192)Ir) sealed source absorbed by an implantable cardioverter defibrillator (ICD) during uterine intracavitary brachytherapy].

The purpose of this study was to verify the dose absorbed by an implantable cardioverter defibrillator (ICD) from an (192)Ir sealed source during uterine intracavitary brachytherapy, and to confirm its immunity to radiation effects. First, prior to treatment, the doses around the ICD position of an anthromorphic phantom were evaluated. Next, we also measured the dose at the ICD position using a fluorescent glass dosimeter and silicon diode dosimeter during the treatment of intracavitary brachytherapy of a patient implanted with an ICD. The results of the phantom study showed the dose percentage at the ICD location, 2 cm deep, to be 0.074% of the prescribed dose. The results of a treatment study similarly showed the dose, measured using a fluorescent glass dosimeter in the ICD position, to be 0.071% of the prescribed dose. During the application of the total prescribed dose, 30 Gy/5 fraction, the dose at the surface of the ICD position was estimated to be 21.2 mGy, well below the 1 Gy maximum recommended in the JASTRO guidelines. We regard dose verification and monitoring during treatment to be both necessary and useful in the treatment of individual cases.

[Verification of the protective effect of a testicular shield in postoperative radiotherapy for seminoma].

In postoperative radiotherapy for seminoma, control of the testicular absorbed dose is important, since exposure of the testis can lead to temporary or permanent infertility. In this case, instead of using a dog-leg-shaped field, treatment using a field focused near the aorta was provided in several disease stages of seminoma. However, the precise need for testicular shielding during treatment and dose of testis exposure was not clear. We examined these questions by measuring the testicular absorbed dose with and without a testicular shield using two clinical treatment plans and a phantom. The distance from the testis phantom and the lower end of the irradiation field was varied. Where the total dose for the tumor was 20 Gy, the testicular absorbed dose was below 0.1 Gy, the threshold dose for temporary infertility. At this dosage, the distance between the testis phantom and the edge of the irradiation field was 14.6 cm without the shield and 9.99 cm with the shield. Using a testes shield, it was thus possible to reduce the dose by 58.5%.

[Dosimetric Properties of Brass Mesh Bolus for High-energy Photon Beam].

PURPOSE: To investigate fundamental dosimetric properties of surface dose, exit dose, and beam profile of the brass mesh bolus for 4, 6, and 10 MV high-energy photon beams in radiation therapy. METHODS: Surface dose and exit dose in the water-equivalent phantom were measured, and percent depth doses (PDDs) were calculated with no bolus, one layer of brass mesh, two layers of brass mesh bolus, three layers of brass mesh bolus, and 0.5 cm tissue-equivalent (TE) bolus. Exit dose was measured at a phantom thickness of 10 cm. Beam profiles were measured at phantom depths of 0 cm and 10 cm. All dosimetry was performed for 4, 6, and 10 MV photon beams using a linear accelerator. RESULTS: The surface dose at a phantom depth of 0 cm increased to 37.3%, 36.3%, and 31.0% for 4, 6, and 10 MV, respectively, with the brass mesh bolus compared to the case of no bolus. The surface dose decreased with one layer of brass mesh bolus compared to that with the 0.5 cm TE bolus. On the other hand, the exit dose increased to 22.0%, 23.1%, and 22.8% for 4, 6, and 10 MV, respectively, with the brass mesh bolus compared to the case of no bolus. The beam profile at the depth of 0 cm showed oscillations, and the difference between the maximum and minimum doses was up to 13.1% with one layer of brass mesh bolus. CONCLUSION: It was suggested that the brass mesh bolus not only increases the surface dose but also has different properties from the conventional TE bolus.

Discovery of selective indole-based prostaglandin D2 receptor antagonist.

A series of N-benzoyl-2-methylindole-3-acetic acids were synthesized and biologically evaluated as prostaglandin (PG) D2 receptor antagonists. Some of the selected compounds significantly inhibited OVA-induced vascular permeability in guinea pig conjunctiva after oral dosing. Structure-activity relationship study is presented.

Design and synthesis of new prostaglandin D2 receptor antagonists.

To identify new cost-effective prostaglandin D2 (DP) receptor antagonists, a series of novel 3-benzoylaminophenylacetic acids were synthesized and biologically evaluated. Among those tested, some representative compounds were found to be orally available. Receptor selectivity and rat PK profiles were also evaluated. The structure-activity relationship (SAR) study is presented.

Discovery of new orally active prostaglandin D2 receptor antagonists.

To identify an orally available drug candidate, a series of 3-benzoylaminophenylacetic acids were synthesized and evaluated as prostaglandin D(2) (PGD(2)) receptor antagonists. Some of the compounds tested were found to exhibit excellent inhibitory activity against cAMP accumulation in human platelet rich plasma (hPRP), which is one of the indexes of DP antagonism. The optimization process including improvement of the physicochemical properties such as solubility, which may result in an improved pharmacokinetic (PK) profile, is presented. Optimized compounds were studied for their pharmacokinetics and in vivo potential. A structure-activity relationship study is also presented. Some of the test compounds were found to have in vivo efficacy towards the inhibition of PGD(2)-induced and OVA-induced vascular permeability in guinea pig conjunctiva.

Syringomyelia associated with Chiari I malformation treated with foramen magnum decompression and duraplasty using a polyglycolic acid patch and fibrin glue: a case report.

A 31-year-old woman presented with worsening numbness and pain in the arms and chest. Neurological findings at admission were decreased pain sensation and temperature sensation in the arms and chest. Magnetic resonance demonstrated a large cervical syrinx from the level of C4 to Th4 associated with Chiari I malformation. Occipital craniectomy and C1 laminectomy were performed for foramen magnum decompression. Intraoperative ultrasonography, performed after removal of the outer membrane of the dura mater at the level of the foramen magnum, revealed insufficient decompression. Therefore, the dura mater was completely opened and duraplasty was performed with a polyglycolic acid patch and fibrin glue. Sufficient decompression was thus achieved. The neurological symptoms and signs improved within the first postoperative month, and magnetic resonance showed a decrease in the size of the syrinx and no cerebrospinal fluid leakage. In patients undergoing foramen magnum decompression with duraplasty, the use of a polyglycolic acid patch and fibrin glue renders suturing unnecessary and avoids the common complications associated with suture duraplasty.

[Ketamine treatment for severe neuropathic pain with cervical spondylotic myelopathy. A case report].

This 60-year-old man with cervical spondylosis experienced bilateral arm pain and weakness. After anterior cervical fusion and posterior decompression at a local hospital his symptoms worsened and he was admitted to our hospital. On admission he manifested bilateral motor weakness, neuropathic pain, and numbness below the C5 level. Radiological findings showed spinal cord compression at the C4 to C7 level. He again underwent posterior decompression and anterior fusion. Although his paresis was improved, his severe neuropathic pain and numbness persisted. Because treatment with NSAIDs, clonazepam, and gabapentin failed to control his symptoms we administered ketamine (NMDA receptor antagonist) because his symptoms were alleviated upon ketamine test challenge. His severe symptoms improved and there were no complications. However, upon cessation of ketamine treatment they reappeared. Therefore, we continued daily ketamine treatment for 6 months, after which we changed to codeine phosphate. His symptoms were controlled without any complications. Ketamine is useful for the control of severe neuropathic pain, however, as long-term ketamine administration is inadvisable, we suggest that treatment be tailored to each patient's particular clinical status.

[Sacroiliac joint dysfunction presented with acute low back pain: three case reports].

Sacroiliac joint (SIJ) can cause low back pain when its joint capsule and ligamentous tissue are damaged. We report our experience in treating three SIJ dysfunction patients presenting with acute low back pain (a 38 year-old male, a 24 year-old male, and a 32 year-old female). SIJ dysfunction was diagnosed using the one-finger test, the modified Newton test, and SIJ injection. In all three patients, lumbar MRI demonstrated slightly degenerated lumbar lesions (lumbar canal stenosis, lumbar disc hernia). Two patients had paresthesia or pain in the leg and all three patients showed iliac muscle tenderness in the groin, which was thought to be a referred symptom because of improvement after SIJ injection. The two male patients returned to work and the problems have not recurred. Although our female patient resumed daily life as a housewife, her condition recurred at intervals of 2-3 months and she required regular SIJ injections. The prevalence of SIJ dysfunction of low back pain is about 10%, so it should be considered as a differential diagnosis when treating low back pain and designing treatment for lumbar spinal disorders.

Treatment of cervical OPLL by cervical anterior fusion using autologous vertebral bone grafts.

BACKGROUND: In anterior fusion, we use autologous bone grafts from cervical vertebral bodies and bioabsorptive screws to prevent graft extrusion (Williams-Isu method). We report the application of and indication for the Williams-Isu method for OPLL and present our clinical and radiological results. METHODS: Using the Williams-Isu method, we treated 17 patients with cervical OPLL; 15 had segmental- and 2 had continuous-type OPLL. The median follow-up term was 24 months. The patients underwent anterior decompression and fusion at a single level (n = 8) or at two levels (n = 9). As a control, 17 patients with cervical spondylosis underwent anterior single-level decompression and fusion using the Williams-Isu method. Pre- and postoperative radiographs of the cervical spine were obtained in all patients, and the alignment of the whole cervical and fused segment and the height of the fused segment were compared. RESULTS: All but one patient experienced alleviation of clinical symptoms without deterioration during the follow-up period. The recovery rate on the JOA score was 71.7%. The patient with continuous-type OPLL suffered postoperative neurological deterioration because of a remnant of the upper-level OPLL. Radiological studies confirmed the absence of bone graft dislocation and fracture, and of satisfactory bone fusion in all patients. There was no significant difference between the two patient groups with respect to whole spine alignment and the alignment and height of the fused segment. CONCLUSIONS: The Williams-Isu method is useful for treating not only cervical spondylosis but also cervical segmental OPLL at one or two levels.

Dosimetric assessment of a single-energy metal artifact reduction algorithm for computed tomography images in radiation therapy.

This study aimed to evaluate the performance of a single-energy metal artifact reduction (SEMAR) algorithm for radiation therapy treatment using phantom cases with metal inserts, assess improvements in computed tomography (CT) number accuracy, and investigate its effects on treatment planning dosimetry. A standard electron density phantom was scanned with and without metal inserts. The numbers of tissue-equivalent materials on both uncorrected and SEMAR-corrected CT images were compared. Treatment planning accuracy was evaluated by comparing dose distributions computed using true density images (without metal inserts), uncorrected images (with metal inserts), and SEMAR-corrected images (with metal inserts) using three-dimensional gamma analysis. The numbers of the true density and uncorrected and SEMAR-corrected CT images in a muscle plug with unilateral inserts were 25.9 HU, - 281.8 HU, and 26.1 HU, respectively. A similar tendency was obtained for other tissue-equivalent materials, and the numbers on CT images were improved with the SEMAR algorithm. In cases involving 1 portal irradiation, 10-MV X-ray, and the Acuros XB algorithm, the pass ratio between the true density and uncorrected images was 89.89%, while that between the true density and SEMAR-corrected images was 95.03%. Improvements in dose distribution were evident using the SEMAR algorithm. Similar trends were found for different irradiation methods and dose calculation algorithms. The SEMAR algorithm can significantly reduce metal artifacts on CT images used for radiation treatment planning. This aspect influenced dosimetry in the region of the artifact and dose distribution was significantly improved with use of the SEMAR-corrected images.

Comparison of the effect of 3 different approaches to the lumbar spinal canal on postoperative paraspinal muscle damage.

BACKGROUND: To assess the effect of 3 different surgical approaches on paraspinal muscle atrophy in patients undergoing lumbar back surgery, we compared their pre- and postoperative CT scans and their serum Hb, CRP, and CPK levels. METHODS: The study population consisted of 71 patients who had undergone lumbar back surgery with microscopic posterior decompression without fusion. We examined the effect on paraspinal muscle atrophy of 3 different approaches to the spinal canal. Group 1 (n = 19) underwent unilateral paraspinal dissection from the spinous process with cutting of the spinous process. In group 2 (n = 24), we used modified bilateral decompression via hemilaminectomy, and group 3 (n = 28) was treated by modified bilateral decompression via spinous process splitting. We measured the levels of CPK, Hb, and CRP preoperatively and on the first postoperative day, and compared the preoperative volume of the paraspinal muscle with the volume measured 1 year after the operation. RESULTS: Age, sex, operative time, and CRP and Hb levels were not statistically different among the 3 groups. The postoperative elevation of CPK was significantly lower in groups 2 and 3 than in group 1. Group 3 manifested a significantly lower degree of atrophic changes of the paraspinal muscle than groups 1 and 2. CONCLUSIONS: We found that among the 3 approaches evaluated, modified bilateral decompression via spinous process splitting is less invasive, facilitates preservation of the paraspinal muscle, and is a useful approach to posterior spinal elements resulting in decreased muscle damage.

Anterior decompression via a wide transvertebral approach and a ceramic insert in a patient with cervical degenerative disease.

BACKGROUND: The transvertebral approach is useful for decompression in patients with cervical radiculopathy; because the intervertebral disk is preserved, moveability is retained. We performed wide deletion of the vertebral body to increase the patient population eligible for treatment with this approach and include patients with compression of the cervical spinal cord. METHODS: In patients undergoing anterior decompression, we performed vertebrotomy (13 x 8 mm) at the midline of the cervical vertebral body at the upper level using a surgical saw. The resulting hole facilitates decompression of the cervical cord and nerve root; a ceramic insert is introduced in the area of deletion. To prevent graft extrusion, the bilateral wings of the bone graft are fastened with bioabsorbable screws. RESULTS: We used this approach in 163 patients with several cervical diseases. Collapse of the vertebral body and fusion of the operated intervertebral disk were encountered in only 1 patient (0.61%). There was no significant difference between pre- and postoperative alignment. Reoperation was required in 7 patients whose symptoms did not improve, in 1 with disk hernia, in 5 with severe spondylosis, and in 1 with combined-type OPLL. CONCLUSIONS: Although this approach is appropriate in patients undergoing cervical anterior decompression, the narrowness of the visual field may result in insufficient decompression, and its indication is restricted to patients with cervical disk hernia, mild cervical spondylosis, and segmental OPLL. In patients with segmental instability, continuous or combined OPLL, severe cervical spondylosis, and kyphosis, this approach should not be used.

Utility of new bioabsorptive screws in cervical anterior fusion.

BACKGROUND: The aim of this study is to report our use of new bioabsorbable screws in cervical anterior fusion. These screws need not be removed because they are completely absorbed by resolution in vivo. We describe our method and the new bioabsorbable screws. METHODS: We used PLLA screws until September 2004 and uncalcined uHA-PLLA screws thereafter. They are completely absorbed by resolution to water and carbon dioxide upon in vivo hydrolysis. The uHA-PLLA screws are x-ray impenetrable, and their uHA content renders them osteoconductive. In cervical anterior fusion, the graft is inserted in the area of deletion resulting from decompression. The screws are inserted in the 4 corners of the vertebral body and graft. In long fusion, they are introduced in the 2 lateral wings of the bone graft on each vertebral body and in the 4 corners. Our method eliminates the need for plates or mesh. RESULTS: We have used this method in 62 patients and encountered no complications. There were no screw or graft extrusions and no surgery-related infections. The patients were able to walk a few hours after the operation and wore a simple neck collar for a few days. CONCLUSIONS: This safe and easy method shortens the hospital stay and reduces the risk of graft extrusion and complications associated with the use of nonabsorbable devices.

[Foraminal stenosis of the lumbar spine treated by decompression with an ultrasonic bone curette: a case report].

Lumbar foramimal stenosis is one of the important disorders underlying radicular symptoms and unrecognized or recurrent foraminal stenosis may result in failed back surgery. We report a 47-year old man with foraminal stenosis of the lumbar spine associated with a bone spur at the pars interarticularis. He suddenly experienced severe right leg pain, lumbago and gait disturbance. Radiographic studies revealed foraminal stenosis on the right L5/S1associated with a bone spur at the pars interarticularis. There was no dural sac compression by spondylolysis. As his symptoms failed to respond to conservative treatment, he underwent decompression without fusion with an ultrasonic bone curette. We performed lateral fenestration and foraminotomy at the right L5/S1 using the extraforaminal approach. After partial foraminotomy, the right L5 nerve root was compressed by the bone spur at the pars interarticularis. For satisfactory decompression we removed the bone spur using an ultrasonic bone curette. His symptoms disappeared immediately after surgery. Although long-term follow-up is necessary, we suggest that microdecompression with an ultrasonic bone curette is a useful method to treat patients with foraminal stenosis of the pars interarticularis.