Endoscopic endonasal excision of nasal chondromesenchymal hamartoma with intracranial extension

INTRODUCTION

Nasal chondromesenchymal hamartoma (NCMH) is an extremely rare benign hamartoma of the sinonasal tract, predominantly involving infants and young children.

METHODS

We report the case of a 3-year-old boy of NCMH with extension to anterior skull base.

RESULTS

The tumor was completely resected piece by piece via an endonasal endoscopic approach. There is no recurrence 3 years after operation.

CONCLUSIONS

We reported the case of NCMH extending to skull base was successfully resected by endonasal endoscopic approach.

Relevance Between Programmed Death Ligand 1 and Radiologic Invasiveness in Pathologic Stage I Lung Adenocarcinoma

BACKGROUND

Programmed death ligand 1 (PD-L1) was reported to predict the response of immunotherapy; however, the association between PD-L1 expression and radiologic and pathologic features has yet to be elucidated.

METHODS

In all, 292 patients with resected pathologic stage I adenocarcinoma were analyzed for PD-L1 expression by immunohistochemistry and evaluated to determine the association between PD-L1 expression and the radiologic/pathologic invasiveness. Specifically, the radiologic invasiveness and noninvasiveness were determined based on the consolidation/tumor ratio, with a cutoff value of 0.25 by thin-section computed tomography.

RESULTS

Among 292 patients, 47 (16.1%) were positive for PD-L1 expression; the remaining 245 patients (83.9%) were negative for PD-L1 expression. Fisher's exact test demonstrated that PD-L1 expression was significantly associated with a higher consolidation/tumor ratio (p = 0.029) and higher maximum standardized uptake value (p = 0.004). The mean values of consolidation/tumor ratio and maximum standardized uptake in patients with and without PD-L1 expression were 0.845 ± 0.052 and 7.241 ± 0.795, and 0.607 ± 0.023 and 3.60 ± 0.364, respectively (p < 0.001 and p < 0.001, respectively). Among 47 adenocarcinomas harboring PD-L1 expression, the frequencies of PD-L1 expression for consolidation/tumor ratios of 0, 0.1 to 0.25, 0.26 to 0.5, and 0.51 or more were 6.4%, 2.1%, 4.3%, and 87.2%, respectively (p = 0.007). Pathologically, PD-L1 was identified exclusively only in more invasive subtypes, not in less invasive ones, such as atypical adenomatous hyperplasia, adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic predominant ones (p < 0.001).

CONCLUSIONS

Expression of PD-L1 was significantly associated with radiologic/pathologic invasive adenocarcinomas. This study provides the first evidence of the radiologic and pathologic invasiveness in resected pathologic stage I adenocarcinoma with PD-L1 expression.

A Monte Carlo study on (223)Ra imaging for unsealed radionuclide therapy

PURPOSE

Radium-223 ((223)Ra), an α-emitting radionuclide, is used in unsealed radionuclide therapy for metastatic bone tumors. The demand for qualitative (223)Ra imaging is growing to optimize dosimetry. The authors simulated (223)Ra imaging using an in-house Monte Carlo simulation code and investigated the feasibility and utility of (223)Ra imaging.

METHODS

The Monte Carlo code comprises two modules, hexagon and nai. The hexagon code simulates the photon and electron interactions in the tissues and collimator, and the nai code simulates the response of the NaI detector system. A 3D numeric phantom created using computed tomography images of a chest phantom was installed in the hexagon code. (223)Ra accumulated in a part of the spine, and three x-rays and 19 γ rays between 80 and 450 keV were selected as the emitted photons. To evaluate the quality of the (223)Ra imaging, the authors also simulated technetium-99m ((99m)Tc) imaging under the same conditions and compared the results.

RESULTS

The sensitivities of the three photopeaks were 147 counts per unit of source activity (cps MBq(-1); photopeak: 84 keV, full width of energy window: 20%), 166 cps MBq(-1) (154 keV, 15%), and 158 cps MBq(-1) (270 keV, 10%) for a low-energy general-purpose (LEGP) collimator, and those for the medium-energy general-purpose (MEGP) collimator were 33, 13, and 8.0 cps MBq(-1), respectively. In the case of (99m)Tc, the sensitivity was 55 cps MBq(-1) (141 keV, 20%) for LEGP and 52 cps MBq(-1) for MEGP. The fractions of unscattered photons of the total photons reflecting the image quality were 0.09 (84 keV), 0.03 (154 keV), and 0.02 (270 keV) for the LEGP collimator and 0.41, 0.25, and 0.50 for the MEGP collimator, respectively. Conversely, this fraction was approximately 0.65 for the simulated (99m)Tc imaging. The sensitivity with the LEGP collimator appeared very high. However, almost all of the counts were because of photons that penetrated or were scattered in the collimator; therefore, the proportions of unscattered photons were small.

CONCLUSIONS

Their simulation study revealed that the most promising scheme for (223)Ra imaging is an 84-keV window using an MEGP collimator. The sensitivity of the photopeaks above 100 keV is too low for (223)Ra imaging. A comparison of the fractions of unscattered photons reveals that the sensitivity and image quality are approximately two-thirds of those for (99m)Tc imaging.

Association between volumetric analysis of lung metastases on F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography and short-term progression after i-131 therapy for differentiated thyroid carcinoma

Purpose:

Lung metastases (LMs) and their radioiodine uptake affect prognosis in patients with differentiated thyroid carcinoma (DTC). We herein investigate the value of metabolic tumor volume (MTV) in LMs on positron emission tomography/computed tomography (PET/CT) using 2-[F-18]-fluoro-2-deoxy-D-glucose (F-18 FDG PET/CT) in predicting short-term progression after initial I-131 therapy in DTC patients.

Materials and Methods:

We retrospectively evaluated 111 DTC patients with LMs. Diagnostic CT and I-131 scintigraphy were performed within 1 week of I-131 therapy. Maximum standardized uptake value (SUVmax) and total MTV (MTVtotal) were compared between patients with I-131-positive and I-131-negative LMs and between patients with and without short-term progression. Correlation analyses were performed between F-18 FDG PET/CT parameters and thyroglobulin (TG) level, and predictive factors for short-term progression were analyzed by logistic regression and receiver operating characteristic curve analysis.

Results:

Patients with short-term progression had significantly higher SUVmax and MTVtotal than those without. TG levels were significantly correlated with SUVmax (r = 0.21) and MTVtotal (r = 0.51) after I-131 therapy. MTVtotal showed significant association (χ² = 16.5, odds ratio = 0.02) with short-term progression after initial I-131 therapy and had the highest predictive value of all the putative risk factors.

Conclusions:

MTVtotal in LMs on F-18 FDG PET/CT is an independent predictive factor with a high predictive value for short-term progression of DTC after initial I-131 therapy. It is recommended that F-18 FDG PET/CT be performed before planning therapy during the evaluation of DTC patients with LM.

The Efficiency of Respiratory-gated 18F-FDG PET/CT in Lung Adenocarcinoma: Amplitude-gating Versus Phase-gating Methods

OBJECTIVES

In positron emission tomography (PET) studies, thoracic movement under free-breathing conditions is a cause of image degradation. Respiratory gating (RG) is commonly used to solve this problem. Two different methods, i.e., phase-gating (PG) and amplitude-gating (AG) PET, are available for respiratory gating. It is important to know the strengths and weaknesses of both methods when selecting an RG method for a given patient. We conducted this study to clarify whether AG or PG is preferable for measuring fluorodeoxyglucose (FDG) accumulation in lung adenocarcinoma and to investigate patient conditions which are most suitable for AG and PG methods.

METHODS

A total of 31 patients (11 males, 20 females; average age: 70.1±11.6 yrs) with 44 lung lesions, diagnosed as lung adenocarcinoma between April 2012 and March 2013, were investigated. Whole-body FDG-PET/CT scan was performed with both PG and AG methods in all patients. The maximum standardized uptake value (SUVmax) of PG, AG, and the control data of these two methods were measured, and the increase ratio (IR), calculated as IR(%)= (Post - Pre)/Pre × 100, was calculated. The diameter and position of lung lesions were also analyzed. We defined an 'effective lesion' of PG (or AG) as a lesion which showed a higher IR compared to AG (or PG). 8 (25.8%).

RESULTS

The average SUVmax and average IR were 8.99±7.94 and %21.4±25.6 in PG and 7.60±6.70 and %4.0±14.4 in AG, respectively. Although there was no significant difference between the average SUVmax of PG and AG (P=0.09), the average IR of PG was significantly higher than that of AG (P<0.01). The number of PG- and AG-effective lesions was 32 (72.7%) and 12 (28.3%), respectively. There was no significant difference in the average diameter or position of the lesions between the PG- and AG-effective lesions. There were 23 (74.2%) PG-effective and 8 (25.8%) AG-effective patients. No significant difference was observed in sex or age between PG- and AG-effective patients.

CONCLUSION

The PG method was more effective for measuring FDG accumulation of lung lesions under free-breathing conditions in comparison with the AG method.

Decontamination of the Activation Product Based on a Legal Revision of the Cyclotron Vault Room on the Non-self-shield Compact Medical Cyclotron

The non-self-shield compact medical cyclotron and the cyclotron vault room were in operation for 27 years. They have now been decommissioned. We efficiently implemented a technique to identify an activation product in the cyclotron vault room. Firstly, the distribution of radioactive concentrations in the concrete of the cyclotron vault room was estimated by calculation from the record of the cyclotron operation. Secondly, the comparison of calculated results with an actual measurement was performed using a NaI scintillation survey meter and a high-purity germanium detector. The calculated values were overestimated as compared to the values measured using the NaI scintillation survey meter and the high-purity germanium detector. However, it could limit the decontamination area. By simulating the activation range, we were able to minimize the concrete core sampling. Finally, the appropriate range of radioactivated area in the cyclotron vault room was decontaminated based on the results of the calculation. After decontamination, the radioactive concentration was below the detection limit value in all areas inside the cyclotron vault room. By these procedures, the decommissioning process of the cyclotron vault room was more efficiently performed.

Research in medical informatics

Medical informatics is concerned with the application of computers in the medical and biological sciences and has been considered a field of research in its own right for more than twenty years. In Malaysia, however, there are very few published efforts in this area. To keep up with research activities carried out worldwide and to create expertise that will be in great demand once the Malaysian Multimedia Super Corridor (MSC) Telemedicine Flagship project is implemented, it is time that Malaysians involved themselves in medical informatics research activities. For this reason, we are proposing a project that will involve the application of an artificial neural network in the domain of cancer. As a prelude to our own research, we review current research in medical informatics. This paper subsequently proposes the use of an artificial neural networks as an alternative tool for investigating cancer survival.

ANN as a tool for medical prognosis

The analysis of cancer survival is used to determine the efficiency of treatment programmes and protocols; it is also used to determine the type of treatment. At the individual level a prediction of cancer survival can help patients make informed decisions with regards to their quality of life and future finances. Currently available prediction methods apply to groups of people, and may not be adequate to predict treatment outcome for individual patients. This paper presents a conceptual model of a cancer knowledge base incorporating a computer-based predictor for survival. It proposes the use of an artificial neural network (ANN) as an alternative tool for investigating cancer survival. The focus of this research will be on nasopharyngeal carcinoma survival data collected in Malaysia.

Shear Stiffness of 4 Common Intracranial Tumors Measured Using MR Elastography: Comparison with Intraoperative Consistency Grading

BACKGROUND AND PURPOSE

The stiffness of intracranial tumors affects the outcome of tumor removal. We evaluated the stiffness of 4 common intracranial tumors by using MR elastography and tested whether MR elastography had the potential to discriminate firm tumors preoperatively.

MATERIALS AND METHODS

Thirty-four patients with meningiomas, pituitary adenomas, vestibular schwannomas, and gliomas scheduled for resection were recruited for MR elastography. On the elastogram, the mean and the maximum shear stiffnesses were measured by placing an ROI on the tumor. Blinded to the MR elastography findings, surgeons conducted qualitative intraoperative assessment of tumor consistency by using a 5-point scale. Histopathologic diagnosis was confirmed by using the resected specimens. The mean and maximum shear stiffnesses were compared with histopathologic subtypes, and the intraoperative tumor consistency was graded by the surgeons.

RESULTS

The mean and maximum shear stiffnesses were the following: 1.9 ± 0.8 kPa and 3.4 ± 1.5 kPa for meningiomas, 1.2 ± 0.3 kPa and 1.8 ± 0.5 kPa for pituitary adenomas, 2.0 ± 0.4 kPa and 2.7 ± 0.8 kPa for vestibular schwannomas, and 1.5 ± 0.2 kPa and 2.7 ± 0.8 kPa for gliomas. The mean and maximum shear stiffnesses for meningiomas were higher than those of pituitary adenomas (P < .05). The mean and maximum shear stiffnesses were significantly correlated with the surgeon's qualitative assessment of tumor consistency (P < .05). The maximum shear stiffness for 5 firm tumors was higher than that of nonfirm tumors (P < .05).

CONCLUSIONS

MR elastography could evaluate intracranial tumors on the basis of their physical property of shear stiffness. MR elastography may be useful in discriminating firm tumors preoperatively.

Abstract P4-11-09: A randomized controlled trial of postoperative adjuvant therapy for elderly breast cancer patients: Comparison of health-related quality of life between clinical trial participants and decliners

Background: Health-related quality of life (HRQoL) is one of the important outcomes in cancer control trials and has increasingly become the one of the primary foci. Obtaining informed consent from participants is essential for participation in randomized controlled trials (RCTs), but the participation in these RCTs may directly influence HRQoL, because treatment options are determined according to the allocation schedule. To date, only a few studies have compared HRQoL between clinical trial participants and decliners.

Patients and Method: The National Surgical Adjuvant Study of Breast Cancer 07 (N-SAS BC 07) is a randomized controlled trial in women with HER2-positive primary breast cancer who are over 70 years of age. The primary aim was to investigate the benefit of trastuzumab monotherapy compared with combination therapy using trastuzumab and chemotherapy. The study concept and design were published in concept paper (Sawaki M. et al., Jpn J Clin Oncol. 2011). In this study, patients were randomized to receive either trastuzumab plus chemotherapy or trastuzumab monotherapy. The primary endpoint was disease-free survival, and the secondary endpoints were overall survival, relapse-free survival, safety, HRQoL, comprehensive geriatric assessment (CGA) and cost effectiveness (protocol ID; NCT01104935).

HRQoL and CGA were assessed at registration (baseline), 2 month, 1 year, and 3 years after the start of protocol treatments using the Functional Assessment of Cancer Therapy-General (FACT-G), Hospital Anxiety and Depression Scale (HADS), EuroQol 5 Dimension (EQ-5D), Tokyo Metropolitan Institute of Gerontology (TMIG) index of competence, and the Philadelphia Geriatric Center (PGC) Morale Scale.

The patients who declined to participate in N-SAS BC 07 were registered in a cohort study to prospectively evaluate the subsequent treatment options and prognosis (07-Cohort). The same questionnaire that was used in N-SAS BC 07 was used in 07-Cohort to evaluate HRQoL and CGA at entry.

Results: Patients were enrolled from October 2012 to October 2016. During this period, 275 and 123 patients were registered in N-SAS BC 07 and 07-Cohort, respectively. The mean age at entry of the patients in the N-SAS BC 07 and 07-Cohort groups was 73.9 and 74.6 years, respectively. The questionnaire response rates at baseline in the patients in N-SAS BC 07 and 07-Cohort groups were 89% and 82%, respectively. There were no significant differences in FACT-G, HADS, EQ-5D, or TMIG index of competence at baseline between the groups, but the mean (standard deviation) scores of PGC Morale Scale in N-SAS BC 07 and 07-Cohort groups were 10.8 (3.3) and 9.9 (3.7), respectively, with the scores being significantly greater in the N-SAS BC 07 group (p=0.020, t-test).

Conclusion: The PGC Morale Scale provides a multidimensional approach to assess the psychological state of older people. This study indicated that participation in the RCT did not affect the baseline QoL of elderly patients but suggested that the baseline QoL of the RCT participants was better than decliners.

Citation Format: Saito T, Sawaki M, Hozumi Y, Sagawa N, Iwata H, Kashiwaba M, Kawashima H, Kobayashi K, Taira N, Takashima T, Takahashi M, Tsuneizumi M, Nakayama T, Baba S, Bando H, Mizuno T, Yamaguchi M, Yamamoto Y, Uemura Y, Ohashi Y, Mukai H. A randomized controlled trial of postoperative adjuvant therapy for elderly breast cancer patients: Comparison of health-related quality of life between clinical trial participants and decliners. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-11-09.

Evaluation of Iterative Reconstruction Method and Attenuation Correction in Brain Dopamine Transporter SPECT Using an Anthropomorphic Striatal Phantom

OBJECTIVES

The aim of this study was to determine the optimal reconstruction parameters for iterative reconstruction in different devices and collimators for dopamine transporter (DaT) single-photon emission computed tomography (SPECT). The results were compared between filtered back projection (FBP) and different attenuation correction (AC) methods.

METHODS

An anthropomorphic striatal phantom was filled with (123)I solutions at different striatum-to-background radioactivity ratios. Data were acquired using two SPECT/CT devices, equipped with a low-to-medium-energy general-purpose collimator (cameras A-1 and B-1) and a low-energy high-resolution (LEHR) collimator (cameras A-2 and B-2). The SPECT images were once reconstructed by FBP using Chang's AC and once by ordered subset expectation maximization (OSEM) using both CTAC and Chang's AC; moreover, scatter correction was performed. OSEM on cameras A-1 and A-2 included resolution recovery (RR). The images were analyzed, using the specific binding ratio (SBR). Regions of interest for the background were placed on both frontal and occipital regions.

RESULTS

The optimal number of iterations and subsets was 10i10s on camera A-1, 10i5s on camera A-2, and 7i6s on cameras B-1 and B-2. The optimal full width at half maximum of the Gaussian filter was 2.5 times the pixel size. In the comparison between FBP and OSEM, the quality was superior on OSEM-reconstructed images, although edge artifacts were observed in cameras A-1 and A-2. The SBR recovery of OSEM was higher than that of FBP on cameras A-1 and A-2, while no significant difference was detected on cameras B-1 and B-2. Good linearity of SBR was observed in all cameras. In the comparison between Chang's AC and CTAC, a significant correlation was observed on all cameras. The difference in the background region influenced SBR differently in Chang's AC and CTAC on cameras A-1 and B-1.

CONCLUSION

Iterative reconstruction improved image quality on all cameras, although edge artifacts were observed in images captured by cameras with RR. The SBR of OSEM with RR was higher than that of FBP, while the SBR of OSEM without RR was equal to that of FBP. Also, the SBR of Chang's AC varied with different background regions in cameras A-1 and B-1.

Monte Carlo simulation of PET and SPECT imaging of 90Y

PURPOSE

Yittrium-90 ((90)Y) is traditionally thought of as a pure beta emitter, and is used in targeted radionuclide therapy, with imaging performed using bremsstrahlung single-photon emission computed tomography (SPECT). However, because (90)Y also emits positrons through internal pair production with a very small branching ratio, positron emission tomography (PET) imaging is also available. Because of the insufficient image quality of (90)Y bremsstrahlung SPECT, PET imaging has been suggested as an alternative. In this paper, the authors present the Monte Carlo-based simulation-reconstruction framework for (90)Y to comprehensively analyze the PET and SPECT imaging techniques and to quantitatively consider the disadvantages associated with them.

METHODS

Our PET and SPECT simulation modules were developed using Monte Carlo simulation of Electrons and Photons (MCEP), developed by Dr. S. Uehara. PET code (MCEP-PET) generates a sinogram, and reconstructs the tomography image using a time-of-flight ordered subset expectation maximization (TOF-OSEM) algorithm with attenuation compensation. To evaluate MCEP-PET, simulated results of (18)F PET imaging were compared with the experimental results. The results confirmed that MCEP-PET can simulate the experimental results very well. The SPECT code (MCEP-SPECT) models the collimator and NaI detector system, and generates the projection images and projection data. To save the computational time, the authors adopt the prerecorded (90)Y bremsstrahlung photon data calculated by MCEP. The projection data are also reconstructed using the OSEM algorithm. The authors simulated PET and SPECT images of a water phantom containing six hot spheres filled with different concentrations of (90)Y without background activity. The amount of activity was 163 MBq, with an acquisition time of 40 min.

RESULTS

The simulated (90)Y-PET image accurately simulated the experimental results. PET image is visually superior to SPECT image because of the low background noise. The simulation reveals that the detected photon number in SPECT is comparable to that of PET, but the large fraction (approximately 75%) of scattered and penetration photons contaminates SPECT image. The lower limit of (90)Y detection in SPECT image was approximately 200 kBq/ml, while that in PET image was approximately 100 kBq/ml.

CONCLUSIONS

By comparing the background noise level and the image concentration profile of both the techniques, PET image quality was determined to be superior to that of bremsstrahlung SPECT. The developed simulation codes will be very useful in the future investigations of PET and bremsstrahlung SPECT imaging of (90)Y.

An improved MR sequence for attenuation correction in PET/MR hybrid imaging

The aim of this study was to investigate the effects of MR parameters on tissue segmentation and determine the optimal MR sequence for attenuation correction in PET/MR hybrid imaging. Eight healthy volunteers were examined using a PET/MR hybrid scanner with six three-dimensional turbo-field-echo sequences for attenuation correction by modifying the echo time, k-space trajectory in the phase-encoding direction, and image contrast. MR images for attenuation correction were obtained from six MR sequences in each session; each volunteer underwent four sessions. Two radiologists assessed the attenuation correction maps generated from the MR images with respect to segmentation errors and ghost artifacts on a five-point scale, and the scores were decided by consensus. Segmentation accuracy and reproducibility were compared. Multiple regression analysis was performed to determine the effects of each MR parameter. The two three-dimensional turbo-field-echo sequences with an in-phase echo time and radial k-space sampling showed the highest total scores for segmentation accuracy, with a high reproducibility. In multiple regression analysis, the score with the shortest echo time (-3.44, P<0.0001) and Cartesian sampling in the anterior/posterior phase-encoding direction (-2.72, P=0.002) was significantly lower than that with in-phase echo time and Cartesian sampling in the right/left phase-encoding direction. Radial k-space sampling provided a significantly higher score (+5.08, P<0.0001) compared with Cartesian sampling. Furthermore, radial sampling improved intrasubject variations in the segmentation score (-8.28%, P=0.002). Image contrast had no significant effect on the total score or reproducibility. These results suggest that three-dimensional turbo-field-echo MR sequences with an in-phase echo time and radial k-space sampling provide improved MR-based attenuation correction maps.

Validation of the Japanese version of the Systemic Lupus Activity Questionnaire that includes physician-based assessments in a large observational cohort

The Systemic Lupus Activity Questionnaire (SLAQ) is a patient-reported outcome for systemic lupus erythematosus (SLE). We aimed to translate it into Japanese and further investigate its validity and reliability. The English version of the SLAQ was translated into Japanese and administered to Japanese SLE patients at our university clinic. Physicians assessed disease activity using the SLE Disease Activity Index 2000 (SLEDAI-2K). The patients were prospectively followed for repeat assessment a year later. Ultimately, 255 patients participated. The patients’ 10-point ratings of disease activity and SLAQ scores were significantly correlated (Spearman’s ρ = 0.53). The SLAQ score was weakly correlated with the SLE Disease Activity Index 2000 (SLEDAI-2K)-nolab (omitting laboratory items; ρ = 0.18) but not with the SLEDAI-2K ( ρ = 0.02). These results suggested its convergent and discriminant validity. The SLAQ demonstrated acceptable internal consistency (Cronbach’s α = 0.80), and good test–retest reliability (intraclass correlation coefficient = 0.85). The effect sizes and the standardized response means of the SLAQ were as follows: clinical worsening, 0.26 and 0.31, and improvement, −0.39 and −0.41, respectively, which indicated a small but significant responsiveness. The Japanese version of the SLAQ demonstrated acceptable reliability and validity; its performance was comparable to that of the original version.

Comparison of positron emission tomography diffusion-weighted imaging (PET/DWI) registration quality in a PET/MR scanner: Zoomed DWI vs. Conventional DWI

PURPOSE

To compare zoomed diffusion-weighted imaging (z-DWI) with reduced field of view (FOV) by spatially selective radiofrequency pulses and conventional echo planar imaging (EPI) DWI (c-DWI) with regard to registration quality using positron emission tomography / magnetic resonance (PET/MR) in patients with malignant tumors.

MATERIALS AND METHODS

Fludeoxyglucose (18(F) ) PET imaging, c-DWI, and z-DWI were conducted simultaneously in 21 patients with known or suspected malignancy using a PET/MR system. A fusion image showing the largest tumor area was generated for analysis. Registration accuracy between PET and DWI was assessed based on the area of maximum overlap and central point displacement of the tumor. EPI factor, echo time (TE), matching area, and displacement were compared between c-DWI and z-DWI by paired t-test. Agreement of apparent diffusion coefficient (ADC) acquired by the two sequences were also assessed with linear regression s and Bland-Altman plot analysis.

RESULTS

Thirty-two lesions were detected on both PET and DWI (mean size 536.3 ± 471.8 mm(2) ). At least one lesion was found in all subjects. In all cases, EPI factor was smaller with z-DWI than c-DWI (43.1 ± 15.6 vs. 62.0 ± 10.0, P < 0.0001), and TE was also shorter for z-DWI (53.6 ± 3.6 msec vs. 65.2 ± 3.6 msec, P < 0.0001). Registration accuracy was better with z-DWI in 30 of 32 lesions (93.8%), and both average matching area and central point displacement were significantly improved (79.8 ± 18.1% vs. 61.8 ± 22.9%, P < 0.0001 and 3.92 ± 2.69 mm vs. 7.51 ± 4.07 mm, P < 0.0001). ADC values calculated with c-DWI and z-DWI showed good agreement.

CONCLUSION

Zoomed DWI reduces image distortion and provides better registration accuracy with PET images.

Anterior mediastinal solid tumours in adults: characterisation using dynamic contrast-enhanced MRI, diffusion-weighted MRI, and FDG-PET/CT

AIM

To find significant parameters to characterise anterior mediastinal solid tumours in adults using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), diffusion-weighted MRI (DWI), and combined 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (FDG-PET/CT).

MATERIALS AND METHODS

Forty-eight histologically confirmed anterior mediastinal solid tumours in 48 patients (24 men, 24 women; age range 21-83 years, mean 50.7 years) were examined. The parameters analysed were maximal diameter, presence of capsule/septa on T2-weighted images, time-signal intensity curves (TICs), apparent diffusion coefficient (ADC), and maximum standardised uptake value (SUVmax). Also examined was whether any differences between histological types could be seen in these parameters. In a validation study, 42 anterior mediastinal solid tumours in 42 patients were examined consecutively.

RESULTS

The washout pattern on TIC was seen only in thymic epithelial tumours (20/32). SUVmax of lymphoma (mean, 17.9), malignant germ cell tumours (14.2), and thymic carcinomas (15.6) were significantly higher than that of thymomas (6.1). The mean maximal diameter of thymic epithelial tumours was significantly smaller than that of lymphomas (p<0.01) and malignant germ cell tumours (p<0.05). The validation study also yielded high accuracy (38/42, 91%) in differentiation among the anterior mediastinal solid tumours.

CONCLUSION

The SUVmax, TIC pattern on DCE-MRI, and maximal diameter might be useful to differentiate anterior mediastinal solid tumours in adults.

Mediastinal paraganglioma

We present a case of mediastinal paraganglioma with radiologic-pathologic correlation. A 48-year-old woman was found incidentally to have a middle mediastinal mass on CT. The mass showed iso-signal intensity compared to that of muscle on T1-weighted images and high signal intensity on T2-weighted images. The lesion showed intermediate intensity on diffusion-weighted imaging, and its apparent diffusion coefficient was 1.72 × 10(-3) mm(2)/s. A contrast-enhanced dynamic study revealed a rapid peak and washout enhancement pattern. (18)F-FDG-PET revealed abnormal uptake in the mediastinal tumor with a maximal standardized uptake value of 7.88. (123)I-meta-iodobenzylguanidine scintigraphy also showed abnormal uptake in the tumor. These findings corresponded to the hypervascularity, rich stroma, low nuclear/cytoplasmic ratio, and nest-forming proliferation of tumor cells with positive neuroendocrine markers.

Cytoplasmic fine network and mitochondria in normal and abnormal cultured keratinocytes: an electron microscopic study using whole-cell observation technique

The cytoplasmic fine structures of both normal human cultured keratinocytes (NHK) and squamous cell carcinoma cells (HSC) were examined by electron microscopy using the whole-cell preparation method and stereo-viewing techniques. The presence of cytoplasmic fine network (CFN) was confirmed in both NHK and HSC, but the structures of the two were found to be radically different. In particular, the mitochondria showed a number of distinct morphological differences. The introduction of cytochalasin B and colchicine into HSC partially destroyed the CFN, and, as a result, the morphology of the HSC mitochondria changed to become similar to those of NHK. It seems that the CFN may have an important role in determining the shape of the cell organelles, such as mitochondria, and that the shape of the mitochondria may perhaps be used as an indication of cell malignancy.

Cytochemical studies of nuclear DNA and RNA in normal and abnormal keratinizing tissues

The distribution patterns of nuclear DNA and RNA in normal and abnormal keratinizing tissues of human skin were examined by electron microscopy, using an enzyme digestion technique. We found that the distribution of nucleic acids in the nuclei of epidermal cells during keratinization changes gradually. In the hair cells, particularly in the cells of hair cortex and Henle's layer of inner root sheath, essentially similar findings were observed. On the other hand, the distribution patterns observed in the tumor cells of calcifying epithelioma and the parakeratotic cells of psoriasis were different from each other and different from the distribution patterns of normal keratinizing tissue, hair, and epidermis. It seems that a similar pattern of reorganization of nucleic acids occurs in the nucleic of normal keratinizing cells as the cells keratinize. However, in abnormal tissue, it seems that the reorganization pattern of nucleic acids in the nuclei is different in each case.