Direct visualization of the three-dimensional shape of skyrmion strings in a noncentrosymmetric magnet

Magnetic skyrmions are topologically stable swirling spin textures that appear as particle-like objects in two-dimensional (2D) systems. Here, utilizing scalar magnetic X-ray tomography under applied magnetic fields, we report the direct visualization of the three-dimensional (3D) shape of individual skyrmion strings in the room-temperature skyrmion-hosting non-centrosymmetric compound Mn_1.4Pt_0.9Pd_0.1Sn. Through the tomographic reconstruction of the 3D distribution of the [001] magnetization component on the basis of transmission images taken at various angles, we identify a skyrmion string running through the entire thickness of the sample, as well as various defect structures, such as the interrupted and Y-shaped strings. The observed point defect may represent the Bloch point serving as an emergent magnetic monopole, as proposed theoretically. Our tomographic approach with a tunable magnetic field paves the way for direct visualization of the structural dynamics of individual skyrmion strings in 3D space, which will contribute to a better understanding of the creation, annihilation and transfer of these topological objects.

Tumor response evaluation in patients with malignant melanoma undergoing immune checkpoint inhibitor therapy and prognosis prediction using 18F-FDG PET/CT: multicenter study for comparison of EORTC, PERCIST, and imPERCIST

OBJECTIVE

In malignant melanoma patients treated with immune checkpoint inhibitor (ICI) therapy, three different FDG-PET criteria, European Organization for Research and Treatment of Cancer (EORTC), PET Response Criteria in Solid Tumors (PERCIST), immunotherapy-modified PERCIST (imPERCIST), were compared regarding response evaluation and prognosis prediction using standardized uptake value (SUV) harmonization of results obtained with various PET/CT scanners installed at different centers.

MATERIALS AND METHODS

Malignant melanoma patients (n = 27) underwent FDG-PET/CT examinations before and again 3 to 9 months after therapy initiation (nivolumab, n = 21; pembrolizumab, n = 6) with different PET scanners at five hospitals. EORTC, PERCIST, and imPERCIST criteria were used to evaluate therapeutic response, then concordance of the results was assessed using Cohen's κ coefficient. Log-rank and Cox methods were employed to determine progression-free (PFS) and overall (OS) survival.

RESULTS

Complete metabolic response (CMR)/partial metabolic response (PMR)/stable metabolic disease (SMD)/progressive metabolic disease (PMD) with harmonized EORTC, PERCIST, and imPERCIST was seen in 3/5/4/15, 4/5/3/15, and 4/5/5/13 patients, respectively. Nearly perfect concordance between each pair of criteria was noted (κ = 0.939-0.972). Twenty patients showed progression and 14 died from malignant melanoma after a median 19.2 months. Responders (CMR/PMR) showed significantly longer PFS and OS than non-responders (SMD/PMD) (harmonized EORTC: p < 0.0001 and p = 0.011; harmonized PERCIST: p < 0.0001 and p = 0.0012; harmonized imPERCIST: p < 0.0001 and p = 0.0012, respectively).

CONCLUSIONS

All harmonized FDG-PET criteria (EORTC, PERCIST, imPERCIST) showed accuracy for response evaluation of ICI therapy and prediction of malignant melanoma patient prognosis. Additional studies to determine their value in larger study populations will be necessary.

Predicting tumor response and prognosis to neoadjuvant chemotherapy in esophageal squamous cell carcinoma patients using PERCIST: a multicenter study in Japan

PURPOSE

To investigate the usefulness of the positron emission tomography response criteria in solid tumors 1.0 (PERCIST1.0) for predicting tumor response to neoadjuvant chemotherapy and prognosis and determine whether PERCIST improvements are necessary for esophageal squamous cell carcinoma (ESCC) patients.

PATIENTS AND METHODS

We analyzed the cases of 177 ESCC patients and examined the association between PERCIST and their pathological responses. Associations of whole-PERCIST with progression-free survival (PFS) and overall survival (OS) were evaluated by a Kaplan-Meier analysis and Cox proportional hazards model. To investigate potential PERCIST improvements, we used the survival tree technique to understand patients' prognoses.

RESULTS

There were significant correlations between the pathologic response and PERCIST of primary tumor (p < 0.001). The optimal cutoff value of the primary tumors' SULpeak response to classify pathologic responses was -50.0%. The diagnostic accuracy of SULpeak response was 87.3% sensitivity, 54.1% specificity, 68.9% accuracy, positive predictive value 60.5%, and negative predictive value 84.1%. Whole-PERCIST was significantly associated with PFS and OS. The survival tree results indicated that a high reduction of the whole SULpeak response was significantly correlated with the patients' prognoses. The cutoff values for the separation of prognoses were - 52.5 for PFS and - 47.1% for OS.

CONCLUSION

PERCIST1.0 can help predict tumor responses and prognoses. However, ¹⁸F-FDG-PET/CT tends to underestimate residual tumors in histopathological response evaluations. Modified PERCIST, in which the partial metabolic response is further classified by the SULpeak response (-50%), might be more appropriate than PERCIST1.0 for evaluating tumor responses and stratifying high-risk patients for recurrence and poor prognosis.

Usefulness of Preoperative 18F-FDG PET/CT for Patients with Thymic Epithelial Tumors

Background

The purpose of this study was to investigate the relationship between preoperative FDG-PET parameters and the World Health Organization (WHO) classification or Masaoka staging system of thymic epithelial tumors.

Methods

We retrospectively reviewed 32 patients with histologically proven thymic epithelial tumors who underwent FDG-PET/CT before surgical resection. FDG-PET parameters, including the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolytic activity (TLG), were measured. These PET parameters were compared in the Masaoka staging system and WHO classification. A receiver operating characteristics (ROC) analysis was performed to identify the cut-off values of PET parameters for the accurate differentiation of early and advanced stages in the Masaoka staging system.

Results

There were 17 low-risk thymomas (1 type A, 9 type AB, and 7 type B1), 8 high-risk thymomas (4 type B2 and 4 type B3), and 7 thymic carcinomas (7 squamous cell carcinoma). Their Masaoka stages were as follows: 24 in the early stage (stages I and II) and 8 in the advanced stage (stage III). Regarding the WHO classification, only SUVmax showed a significant difference (P < 0.05). In the Masaoka stage, all PET parameters were significantly higher in the advanced stage than in the early stage (P < 0.05). In the ROC analysis to predict the early and advanced stages in thymic epithelial tumors, the area under the curve was the highest for TLG among the PET parameters examined and the cut-off value of TLG for discriminating the early from advanced stage with maximal sensitivity and specificity was 30.735.

Conclusion

Although volumetric PET parameters, such as MTV and TLG, did not correlate with the WHO classification, a significant correlation was observed between SUVmax and the WHO classification. In the Masaoka staging system, volumetric PET parameters may achieve more precise staging than SUVmax.

Intra- and inter-observer agreement in the visual interpretation of interim 18F-FDG PET/CT in malignant lymphoma: influence of clinical information

Background Interim PET/CT is widely performed in lymphoma patients in clinical practice and clinical trials. Visual assessment using a 5-point scale is proposed for PET/CT interpretation, but intra- and inter-observer variation is not fully investigated. Purpose To investigate intra- and inter-observer variations in the reporting of interim positron emission tomography/computed tomography (PET/CT) in lymphoma patients, and the influence of clinical information on the interpretation. Material and Methods Three expert readers from different institutions interpreted interim PET/CT images of 42 consecutive patients with malignant lymphoma twice, with and without clinical information. The intra- and inter-observer agreements were calculated using the kappa statistic on a patient and a region basis. Results On a patient basis, intra-observer agreement, inter-observer agreement without information, and inter-observer agreement with information were within the ranges 0.48-0.62, 0.51-0.62, and 0.42-0.76, respectively. In the evaluation of lymph nodes, intra-observer agreement, inter-observer agreement without information, and inter-observer agreement with information were within the ranges 0.78-0.92, 0.80-0.82, and 0.77-0.83, respectively. Observer agreements were in almost perfect to substantial agreement categories for most lymphatic organs, but were generally low for the other organs. Conclusion The intra- and inter-observer agreements in evaluating interim PET/CT were relatively low for extranodal lesions, but they were substantial to almost perfect when interpreting nodal regions in malignant lymphoma, irrespective of the provision of clinical information, although memory at the first interpretation might have affected the intra-observer results.

Role of Neuroimaging on Differentiation of Parkinson's Disease and Its Related Diseases

An accurate diagnosis of Parkinson's disease (PD) is a prerequisite for therapeutic management. In spite of recent advances in the diagnosis of parkinsonian disorders, PD is misdiagnosed in between 6 and 25% of patients, even in specialized movement disorder centers. Although the gold standard for the diagnosis of PD is a neuropathological assessment, neuroimaging has been playing an important role in the differential diagnosis of PD and is used for clinical diagnostic criteria. In clinical practice, differential diagnoses of PD include atypical parkinsonian syndromes such as dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, caused by a striatal dopamine deficiency following nigrostrial degeneration. PD may also be mimicked by syndromes not associated with a striatal dopamine deficiency such as essential tremor, drug-induced parkinsonism, and vascular parkinsonism. Moreover, difficulties are associated with the clinical differentiation of patients with parkinsonism from those with Alzheimer's disease. In this review, we summarize the typical imaging findings of PD and its related diseases described above using morphological imaging modalities (conventional MR imaging and neuromelanin MR imaging) and functional imaging modalities (^99mTc-ethyl cysteinate dimer perfusion single photon emission computed tomography, ¹²³I-metaiodobenzylguanidine myocardial scintigraphy, and ¹²³I-FP-CIT dopamine transporter single photon emission computed tomography) that are clinically available in most hospitals. We also attempt to provide a diagnostic approach for the differential diagnosis of PD and its related diseases in clinical practice.

Evaluation of Parkinson's disease by neuromelanin-sensitive magnetic resonance imaging and 123I-FP-CIT SPECT

Background Both neuromelanin-sensitive magnetic resonance imaging (NmMRI) and ¹²³I-FP-CIT single photon emission computed tomography (SPECT) (DaTSCAN) assist the diagnosis of Parkinson's disease (PD). However, there have been few studies investigating a correlation between them. Purpose To correlate the utility of NmMRI and DaTSCAN and to evaluate the relationship between both imaging findings and the Unified PD rating scale part III (UPDRS III) score for the diagnosis and management of PD. Material and Methods Seventeen patients with PD who underwent both NmMRI and DaTSCAN were included. We measured the volume of the neuromelanin-positive substantia nigra pars compacta (SNc volume) on NmMRI and measured the specific binding ratio (SBR) on DaTSCAN. The asymmetry index (AI) of the SNc volume and SBR were also calculated. We evaluated the relationship between the UPDRS III score and the SNc volume and SBR, respectively. Results The SNc volume showed a significant correlation with the SBR. The AIs of them also showed a significant correlation. Both the mean of the bilateral SBR and the mean of the bilateral SNc volume showed significant negative correlations with the UPDRS III score. However, the correlation between the SBR and the UPDRS III score was stronger than that between the SNc volume and the UPDRS III score. Conclusion Both NmMRI and DaTSCAN are helpful for PD diagnosis. However, we conclude that DaTSCAN is more suitable for the evaluation of the clinical motor severity and would be more useful for the management of PD patients than NmMRI.

The utility of FDG-PET for detecting multiple primary cancers in hypopharyngeal cancer patients

Aim: To examine the utility of 2'-[18F]-fluoro-2'-deoxy-D-glucose positron emission tomography (FDG-PET) for detecting multiple primary cancers (MPC) in patients with hypopharyngeal cancer (HPC). Patients, methods: Seventy patients with HPC underwent FDGPET to determine the staging. Routine clinical examinations were carried out, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), and oesophagealgastroduodenoscopy (EGDS). The detection rate of synchronous and metachronous cancer was calculated based on FDG-PET alone or FDG-PET combined with clinical routine examination. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy were used to diagnose oesophageal cancer using FDG-PET. Results: Of the 70 patients, 12 (17.1%) had 15 synchronous tumours, and 2 of the 58 remaining patients (3.4%) had metachronous tumours. Oesophageal cancer was discovered most frequently: superficial type (n = 6), advanced type (n = 4). On a per-patient basis, 11 of 12 patients (91.6%) were diagnosed with synchronous tumours, and on a per-lesion basis, 12 of 15 lesions (80.0%) were detected by FDG-PET. The sensitivity, specificity, accuracy, PPV, and NPV of FDG-PET regarding oesophageal cancer were 70%, 100%, 95.7%, 100%, and 95.2% respectively. Three of the six superficial types were positive on FDG-PET. Both of the metachronous tumour lesions were detected by FDG-PET. Conclusion: FDG-PET is useful for estimating the MPC in HPC patients. Since 3 of 10 synchronous oesophageal cancer were missed with PET alone, a combination with EGDS should be considered to exclude synchronous oesophageal cancer.

Oxygen-15 labeled CO2, O2, and CO PET in small animals: evaluation using a 3D-mode microPET scanner and impact of reconstruction algorithms

Background

Positron emission tomography (PET) studies using ¹⁵O-labeled CO₂, O₂, and CO have been used in humans to evaluate cerebral blood flow (CBF), the cerebral oxygen extraction fraction (OEF), and the cerebral metabolic rate of oxygen (CMRO₂) and cerebral blood volume (CBV), respectively. In preclinical studies, however, PET studies using ¹⁵O-labeled gases are not widely performed because of the technical difficulties associated with handling labeled gases with a short half-life. The aims of the present study were to evaluate the scatter fraction using 3D-mode micro-PET for ¹⁵O-labeled gas studies and the influence of reconstruction algorithms on quantitative values.

Nine male SD rats were studied using the steady state inhalation method for ¹⁵O-labeled gases with arterial blood sampling. The resulting PET images were reconstructed using filtered back projection (FBP), ordered-subset expectation maximization (OSEM) 2D, or OSEM 3D followed by maximum a posteriori (OSEM3D-MAP). The quantitative values for each brain region and each reconstruction method were calculated by applying different reconstruction methods.

Results

The quantitative values for the whole brain as calculated using FBP were 46.6 ± 12.5 mL/100 mL/min (CBF), 63.7 ± 7.2% (OEF), 5.72 ± 0.34 mL/100 mL/min (CMRO₂), and 5.66 ± 0.34 mL/100 mL (CBV), respectively. The CBF and CMRO₂ values were significantly higher when the OSEM2D and OSEM3D-MAP reconstruction methods were used, compared with FBP, whereas the OEF values were significantly lower when reconstructed using OSEM3D-MAP.

Conclusions

We evaluated the difference in quantitative values among the reconstruction algorithms using 3D-mode micro-PET. The iterative reconstruction method resulted in significantly higher quantitative values for CBF and CMRO₂, compared with the values calculated using the FBP reconstruction method.

Electronic supplementary material

The online version of this article (10.1186/s13550-017-0335-7) contains supplementary material, which is available to authorized users.

Pictorial review of 18F-FDG PET/CT findings in musculoskeletal lesions

We herein reviewed ¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) findings in a number of musculoskeletal lesions including malignant tumors, benign tumors, and tumor-like lesions with correlations to other radiographic imaging modalities, and described the diversity of the ¹⁸F-FDG PET/CT findings of this entity. Malignant primary musculoskeletal tumors are typically ¹⁸F-FDG avid, whereas low-grade malignant tumors show mild uptake. Benign musculoskeletal tumors generally show a faint uptake of ¹⁸F-FDG, and tumor-like conditions also display various uptake patterns of ¹⁸F-FDG. Although musculoskeletal tumors show various uptakes of ¹⁸F-FDG on PET/CT, its addition to morphological imaging modalities such as CT and MRI is useful for the characterization and differentiation of musculoskeletal lesions.

Ceramide limits phosphatidylinositol-3-kinase C2β-controlled cell motility in ovarian cancer: potential of ceramide as a metastasis-suppressor lipid

Targeting cell motility, which is required for dissemination and metastasis, has therapeutic potential for ovarian cancer metastasis, and regulatory mechanisms of cell motility need to be uncovered for developing novel therapeutics. Invasive ovarian cancer cells spontaneously formed protrusions, such as lamellipodia, which are required for generating locomotive force in cell motility. Short interfering RNA screening identified class II phosphatidylinositol 3-kinase C2β (PI3KC2β) as the predominant isoform of PI3K involved in lamellipodia formation of ovarian cancer cells. The bioactive sphingolipid ceramide has emerged as an antitumorigenic lipid, and treatment with short-chain C6-ceramide decreased the number of ovarian cancer cells with PI3KC2β-driven lamellipodia. Pharmacological analysis demonstrated that long-chain ceramide regenerated from C6-ceramide through the salvage/recycling pathway, at least in part, mediated the action of C6-ceramide. Mechanistically, ceramide was revealed to interact with the PIK-catalytic domain of PI3KC2β and affect its compartmentalization, thereby suppressing PI3KC2β activation and its driven cell motility. Ceramide treatment also suppressed cell motility promoted by epithelial growth factor, which is a prometastatic factor. To examine the role of ceramide in ovarian cancer metastasis, ceramide liposomes were employed and confirmed to suppress cell motility in vitro. Ceramide liposomes had an inhibitory effect on peritoneal metastasis in a murine xenograft model of human ovarian cancer. Metastasis of PI3KC2β knocked-down cells was insensitive to treatment with ceramide liposomes, suggesting specific involvement of ceramide interaction with PI3KC2β in metastasis suppression. Our study identified ceramide as a bioactive lipid that limits PI3KC2β-governed cell motility, and ceramide is proposed to serve as a metastasis-suppressor lipid in ovarian cancer. These findings could be translated into developing ceramide-based therapy for metastatic diseases.

Distribution of intravenously administered acetylcholinesterase inhibitor and acetylcholinesterase activity in the adrenal gland: 11C-donepezil PET study in the normal rat

Purpose

Acetylcholinesterase (AChE) inhibitors have been used for patients with Alzheimer's disease. However, its pharmacokinetics in non-target organs other than the brain has not been clarified yet. The purpose of this study was to evaluate the relationship between the whole-body distribution of intravenously administered ¹¹C-Donepezil (DNP) and the AChE activity in the normal rat, with special focus on the adrenal glands.

Methods

The distribution of ¹¹C-DNP was investigated by PET/CT in 6 normal male Wistar rats (8 weeks old, body weight  = 220±8.9 g). A 30-min dynamic scan was started simultaneously with an intravenous bolus injection of ¹¹C-DNP (45.0±10.7 MBq). The whole-body distribution of the ¹¹C-DNP PET was evaluated based on the Vt (total distribution volume) by Logan-plot analysis. A fluorometric assay was performed to quantify the AChE activity in homogenized tissue solutions of the major organs.

Results

The PET analysis using Vt showed that the adrenal glands had the 2nd highest level of ¹¹C-DNP in the body (following the liver) (13.33±1.08 and 19.43±1.29 ml/cm³, respectively), indicating that the distribution of ¹¹C-DNP was the highest in the adrenal glands, except for that in the excretory organs. The AChE activity was the third highest in the adrenal glands (following the small intestine and the stomach) (24.9±1.6, 83.1±3.0, and 38.5±8.1 mU/mg, respectively), indicating high activity of AChE in the adrenal glands.

Conclusions

We demonstrated the whole-body distribution of ¹¹C-DNP by PET and the AChE activity in the major organs by fluorometric assay in the normal rat. High accumulation of ¹¹C-DNP was observed in the adrenal glands, which suggested the risk of enhanced cholinergic synaptic transmission by the use of AChE inhibitors.

Paradoxical reduction of cerebral blood flow after acetazolamide loading: a hemodynamic and metabolic study with (15)O PET

Paradoxical reduction of cerebral blood flow (CBF) after administration of the vasodilator acetazolamide is the most severe stage of cerebrovascular reactivity failure and is often associated with an increased oxygen extraction fraction (OEF). In this study, we aimed to reveal the mechanism underlying this phenomenon by focusing on the ratio of CBF to cerebral blood volume (CBV) as a marker of regional cerebral perfusion pressure (CPP). In 37 patients with unilateral internal carotid or middle cerebral arterial (MCA) steno-occlusive disease and 8 normal controls, the baseline CBF (CBF(b)), CBV, OEF, cerebral oxygen metabolic rate (CMRO2), and CBF after acetazolamide loading in the anterior and posterior MCA territories were measured by (15)O positron emission tomography. Paradoxical CBF reduction was found in 28 of 74 regions (18 of 37 patients) in the ipsilateral hemisphere. High CBF(b) (> 47.6 mL/100 mL/min, n = 7) was associated with normal CBF(b)/CBV, increased CBV, decreased OEF, and normal CMRO2. Low CBF(b) (< 31.8 mL/100 mL/min, n = 9) was associated with decreased CBF(b)/CBV, increased CBV, increased OEF, and decreased CMRO2. These findings demonstrated that paradoxical CBF reduction is not always associated with reduction of CPP, but partly includes high-CBF(b) regions with normal CPP, which has not been described in previous studies.

Clinical significance of miR-144-ZFX axis in disseminated tumour cells in bone marrow in gastric cancer cases

BACKGROUND

We previously reported that bone marrow (BM) was a homing site for gastric cancer (GC) cells leading to haematogenous metastases. There has been little study that microRNAs regulated pathways in malignant cells or host cells in BM, and thereby regulated the progression of GC.

METHODS

Both microRNA microarray and gene expression microarray analyses of total RNA from BM were conducted, comparing five early and five advanced GC patients. We focused on miR-144-ZFX axis as a candidate BM regulator of GC progression and validated the origin of the microRNA expression in diverse cell fractions (EpCAM(+)CD45(-), EpCAM(-)CD45(+), and CD14(+)) by magnetic-activated cell sorting (MACS).

RESULTS

Quantitative reverse-transcriptase (RT)-PCR analysis validated diminished miR-144 expression in stage IV GC patients with respect to stage I GC patients (t-test, P=0.02), with an inverse correlation to ZFX (ANOVA, P<0.01). Luciferase reporter assays in five GC cell lines indicated their direct binding and validated by western blotting. Pre-miR144 treatment and the resultant repression of ZFX in GC cell lines moderately upregulated their susceptibility to 5-fluorouracil chemotherapy. In MACS-purified BM fractions, the level of miR-144 expression was significantly diminished in disseminated tumour cell fraction (P=0.0005). Diminished miR-144 expression in 93 cases of primary GC indicated poor prognosis.

CONCLUSION

We speculate that disseminated cancer cells could survive in BM when low expression of miR-144 permits upregulation of ZFX. The regulation of the miR-144-ZFX axis in cancer cells has a key role in the indicator of the progression of GC cases.

Detection and localization of prostate cancer with the targeted biopsy strategy based on ADC map: a prospective large-scale cohort study

Purpose

To investigate the usefulness of targeted biopsy strategy based on apparent diffusion coefficient (ADC) maps in the detection and localization of prostate cancer.

Materials and Methods

Institutional review board approval and informed consent from all participants were obtained. This study included 1448 consecutive patients suspected of having prostate cancer based on PSA level, who were divided into two groups: Group A included 890 patients with low-ADC lesions who underwent targeted and systematic biopsies; Group B included 558 patients with no low-ADC lesions who underwent only systematic biopsies. The cancer detection rates (CDR) of each group, positive predictive value (PPV), and negative predictive value (NPV) of ADC maps were calculated.

Results

The CDR was 70.1% for Group A, higher than those for overall patients (48.1%) and for Group B (13.1%) with significant difference (P < 0.001). In the serum, PSA range from 4 to 20 ng/mL, the CDR was higher for the Group A than for the Group B and overall patients with significant differences. PPV and NPV of MR findings were 70.1% and 86.9%, respectively. Especially, the PPV of the MR findings for the anterior portion was as high as 90.1%. Among the false negatives of MR findings, Gleason score proved 6 or smaller in 79.5%, and positive core number was merely one or two in 80.8%.

Conclusion

The targeted biopsy strategy based on ADC maps can be useful in the detection and localization of prostate cancer with high PPV. J. Magn. Reson. Imaging 2012;35:1414–1421. © 2012 Wiley Periodicals, Inc.

Capsule of parotid gland tumor: evaluation by 3.0 T magnetic resonance imaging using surface coils

BACKGROUND

magnetic resonance (MR) imaging of parotid gland tumors has been widely reported, although few reports have evaluated the capsule of parotid gland tumors in detail.

PURPOSE

to evaluate the diagnostic usefulness of 3.0 T MR imaging with surface coils for detection of the parotid gland tumor capsule, and to clarify the characteristics of the capsules.

MATERIAL AND METHODS

seventy-eight patients with parotid gland tumors (63 benign and 15 malignant) were evaluated. Axial and coronal T2-weighted and contrast-enhanced T1-weighted images were obtained using a 3.0 T MR scanner with 70 mm surface coils. It was retrospectively assessed whether each parotid gland tumor was completely surrounded by a capsule. The capsule was classified as regular or irregular in terms of capsular thickness, and as none, mildly, or strongly enhancing in terms of contrast enhancement. Visual interpretations were compared with histopathological findings to evaluate the diagnostic ability of MR imaging to detect parotid gland tumor capsules. Statistical evaluation was conducted concerning the presence of capsules, capsular irregularity, and the difference in contrast enhancement between benign and malignant tumors, and that between pleomorphic adenomas and Warthin's tumors.

RESULTS

capsules completely surrounding the tumor on MR imaging yielded a sensitivity of 87.7% (50/57), specificity of 90.5% (19/21), and accuracy of 88.5% (69/78). Benign tumors had a capsule completely surrounding the tumor significantly more often than malignant tumors (P = 0.009). Concerning capsular irregularity, malignant tumors tended to have more irregular capsules than benign tumors, although there were no significant differences. The capsules of malignant tumors enhanced significantly more strongly than those of benign tumors (P = 0.018).

CONCLUSION

3.0 T MR imaging using surface coils could correctly depict parotid gland tumor capsules in most cases. Most benign and some malignant tumors had capsules completely surrounding the tumors. Malignancy should be considered in tumors with irregular and strongly enhancing capsules.

Fractional allelic loss as a potential biomarker of risk prediction in early-stage mucinous ovarian tumors of low malignant potential

Ovarian tumors of low malignant potential (LMP) appear to be intermediate between adenomas and ovarian carcinomas. Such tumors are often associated with a significantly better prognosis than for ovarian carcinomas. However, a subset of LMPs can progress and become lethal even in patients with early-stage disease. In order to seek sensitive diagnostic tools to monitor patients after surgical therapy, we performed a genome-wide scan for LOH in 37 early-stage mucinous LMPs using 91 polymorphic microsatellite markers at an average interval of 50 cM across all of the human chromosomes and 25 LOH markers reported to be associated with ovarian carcinoma. Fractional allelic loss (FAL) values were calculated as (loci scored with LOH)/(total informative loci) for each sample. With respect to tumor recurrence, high FAL values were more frequent in recurrent tumors than in non-recurrent tumors. Using the screening markers, FAL values for recurrent tumors were significantly higher than for non-recurrent tumors (19.8% vs 6.3%, respectively, p < 0.0001). Similar results were obtained using the hotspot markers (22.2% vs 7.1%, respectively, p < 0.0001). A significant correlation between FAL values obtained using screening markers and those based on hotspot markers was observed (R = 0.460, p = 0.003). Our findings suggest that a specific type of genetic instability (i.e., chromosomal instability, CIN) may exist in mucinous LMPs, and that this instability may indicate tumors with an aggressive biological nature. Therefore, FAL values may represent a new biomarker for risk prediction in early-stage mucinous LMP tumors.

Therapy-related myelodysplasia and acute myeloid leukemia following paclitaxel- and carboplatin-based chemotherapy in an ovarian cancer patient: a case report and literature review

Alkylating agents have strong leukemogenic potential. There are a number of recent acute myeloid leukemia (t-AML) cases related to previous paclitaxel exposure. These leukemias tend to be of aggressive subtypes with long-latency periods. Unlike previously reported cases, the present case was of the secondary acute megakaryoblastic myeloid leukemia (AML M7) subtype. Additionally, it did not harbor a translocation in chromosome 19. A 73-year-old woman was diagnosed with t-AML M7 with antecedent myelodysplasia. Leukemia followed a second induction of paclitaxel- and carboplatin-based chemotherapy for recurrent ovarian cancer. Her second induction began 25 months after completion of her first course of chemotherapy. The increased incidence of postpaclitaxel leukemia suggests a probable role for paclitaxel as a leukemogenic agent. It highlights the importance of assessing for leukemia risk factors prior to beginning paclitaxel therapy.

A case of extremely chemoresistant pure pleomorphic rhabdomyosarcoma of the uterus associated with a high serum LDH level

BACKGROUND

Pleomorphic rhabdomyosarcoma (RMS) of gynecologic origin is an exceedingly rare, highly malignant tumor. Only a few cases have been reported in the last decades.

CASE REPORT

A 60-year-old postmenopausal woman presented with a high LDH level of unknown origin. Ultimately, she was diagnosed with pleomorphic RMS. She underwent total hysterectomy, bilateral salpingo-oophorectomy, left pelvic and paraaortic lymphadenectomy and partial omentectomy. Surgery was followed by systemic chemotherapy and pelvic irradiation. Unfortunately, the patient did not respond to treatment. Her disease course correlated with the fluctuation of plasma LDH levels. Ultimately she died within 20 months of the diagnosis.

CONCLUSION

It is important to have better insight and to set a standard multimodal treatment for adult RMS. In addition, plasma LDH levels can be considered as a prognostic marker for RMS, particularly in advanced stage.

Leptin facilitates learning and memory performance and enhances hippocampal CA1 long-term potentiation and CaMK II phosphorylation in rats

Leptin, an adipocytokine encoded by an obesity gene and expressed in adipose tissue, affects feeding behavior, thermogenesis, and neuroendocrine status via leptin receptors distributed in the brain, especially in the hypothalamus. Leptin may also modulate the synaptic plasticity and behavioral performance related to learning and memory since: leptin receptors are found in the hippocampus, and both leptin and its receptor share structural and functional similarities with the interleukin-6 family of cytokines that modulate long-term potentiation (LTP) in the hippocampus. We therefore examined the effect of leptin on (1) behavioral performance in emotional and spatial learning tasks, (2) LTP at Schaffer collateral-CA1 synapses, (3) presynaptic and postsynaptic activities in hippocampal CA1 neurons, (4) the intracellular Ca(2+) concentration ([Ca(2+)](i)) in CA1 neurons, and (5) the activity of Ca(2+)/calmodulin protein kinase II (CaMK II) in the hippocampal CA1 tissue that exhibits LTP. Intravenous injection of 5 and/or 50mug/kg, but not of 500mug/kg leptin, facilitated behavioral performance in passive avoidance and Morris water-maze tasks. Bath application of 10(-12)M leptin in slice experiments enhanced LTP and increased the presynaptic transmitter release, whereas 10(-10)M leptin suppressed LTP and reduced the postsynaptic receptor sensitivity to N-methyl-d-aspartic acid. The increase in the [Ca(2+)](i) induced by 10(-10)M leptin was two times greater than that induced by 10(-12)M leptin. In addition, the facilitation (10(-12)M) and suppression (10(-10)M) of LTP by leptin was closely associated with an increase and decrease in Ca(2+)-independent activity of CaMK II. Our results show that leptin not only affects hypothalamic functions (such as feeding, thermogenesis, and neuroendocrine status), but also modulates higher nervous functions, such as the behavioral performance related to learning and memory and hippocampal synaptic plasticity.

Elevated cerebrospinal fluid lactate levels and the pathomechanism of calcification in Fahr's disease

In this study, we report the case of a 68-year-old man complaining of involuntary movement of his left shoulder and lower jaw plus dyspnea. On cranial computed tomography and magnetic resonance imaging, marked and symmetrical calcification at the basal ganglia and dentate nuclei was documented. An elevated cerebrospinal fluid (CSF) lactate level was confirmed by spinal tap examination and magnetic resonance spectroscopy. The raised CSF lactate level, clinical characteristics such as diabetes, bilateral hearing loss and symmetrical cerebral calcification strongly suggested some kinds of mitochondrial disease. However, gene analysis of peripheral blood leukocytes revealed no typical or known mutations. Under the diagnosis of Fahr's disease, we treated him with haloperidol, which completely abolished his symptoms. In Ellsworth-Howard test, he showed markedly decreased phosphaturic response to parathyroid hormone with same pattern as type 2 pseudohypoparathyroidism. This abnormal response in our patient, probably due to respiratory alkalosis reflecting chronic hyperventilation, might in part explain similar mechanism of ectopic calcification underlying these two diseases.

Follow-up assessment of the collateral circulation in patients with Kawasaki disease who underwent dipyridamole stress technetium-99m tetrofosmin scintigraphy

To assess the alteration of myocardial ischemic findings and the role of collateral vessels in patients with Kawasaki disease (KD), we used dipyridamole stress technetium-99m tetrofosmin (Tf) single photon emission computed tomography (SPECT). A comparison study of coronary angiography and dipyridamole stress (0.70 mg/kg) Tf-SPECT was repeated at least twice in 20 patients. The subjects included 7 patients with coronary stenosis, 1 with pre- and post-coronary artery bypass grafting (CABG) due to coronary stenosis, 1 with progression to coronary stenosis, and 11 with persistent coronary aneurysms. In the stenosis group, Tf-SPECT revealed that 6 of the 7 patients had some degree of ischemic findings, and 5 of these 6 did not show any change in their ischemic findings during follow-up. In 1 patient, the ischemic findings changed according to the collateral circulation changes. The patient who underwent CABG had pre-CABG ischemic changes that disappeared after CABG. In the patient whose coronary arteries progressed to stenosis, the ischemic findings progressed as the coronary stenosis progressed. In the persistent aneurysm group, there were no ischemic findings. In the future Tf-SPECT may become one of the most useful methods for monitoring the progressive changes of myocardial ischemia in KD.

Morphological imaging in the localization of neuroendocrine gastroenteropancreatic tumors found by somatostatin receptor scintigraphy

PURPOSE

To evaluate the necessity of morphological images (MI) in reading somatostatin receptor scintigraphy (SRS) in patients with suspected neuroendocrine gastroenteropancreatic (GEP) tumors.

MATERIAL AND METHODS

A Japanese multicenter clinical trial of SRS was conducted in 40 patients with suspected GEP tumors. Three experienced radiologists interpreted the images in three separate sessions in a blinded manner (1: SRS images alone, 2: MI alone, 3: SRS and MI analyzed simultaneously), and the reading results of each session were compared. In addition, the diagnostic abilities of SRS, MI and SRS alone and simultaneous SRS and MI readings were compared for patients where final diagnosis was obtained.

RESULTS

SRS detected more suspected lesions (positive or inconclusive uptake) than morphological images did (51 vs 27 lesions), but included many physiological uptakes detected as positive or inconclusive uptakes. Combined reading of SRS and morphological images helped to correctly recognize these physiological uptakes, and also helped in determining the anatomical localization of the abnormal uptakes. Combined reading of SRS and morphological images gave the highest diagnostic impact.

CONCLUSION

The sensitivity of SRS with regard to GEP is high. However the specificity is very low. Morphologic imaging is necessary for the exclusion of physiological uptake and correct anatomic location of an abnormal tracer uptake. The combined reading of SRS and morphologic imaging studies gives the highest diagnostic impact.

Relationship between intraoperative transoesophageal echocardiography findings and perfusion lung scintigraphy results on first postoperative day

BACKGROUND

Although intraoperative transoesophageal echocardiography (TOE) has been used to detect the occurrence of echogenic macro- and/or microembolic phenomena during total hip arthroplasty (THA), no direct correlation between macroembolism and the formation of pulmonary embolism (PE) has been conclusively determined in early postoperative periods after THA.

METHODS

Sixty-two patients scheduled for primary THA were enrolled in this study. Intraoperative TOE images were continuously recorded on videotape and the echogenic events were evaluated throughout surgery. Perfusion lung scintigraphy was performed on the first postoperative day (POD1).

RESULTS

Perfusion lung scintigraphy revealed the existence of PE in nine (15%) of the 62 patients who underwent THA: five (25%) of 20 patients with cemented THA and four (10%) of 42 patients with non-cemented THA. The grading score of intraoperative TOE findings, including the amount of echogenic particles in right atrium, the longest time of echogenesis and the diameter of the largest echogenic particles, did not differ between the groups with and without PE. The sensitivity, specificity, and positive and negative predictive values for the detection of echogenic macroemboli for the prediction of the development of PE on POD1 were 0.78, 0.60, 0.25 and 0.94, respectively.

CONCLUSION

Intraoperative TOE monitoring did not predict the occurrence of PE on POD1.

A polymorphism of DRD2 gene and brain atrophy in methamphetamine psychosis

Our group, Ujike et al., recently reported that the A1 allele of TaqI A polymorphism of the dopamine receptor D2 (DRD2) gene, associated with transient psychosis, significantly differs from that of patients with prolonged psychosis in methamphetamine psychosis. Therefore, we examined the association between the TaqI A polymorphism of the DRD2 gene and the brain MRI view for patients with methamphetamine psychosis. The subjects underwent brain MRI scans using the FLAIR method. Genotyping was performed by PCR-RFLP methods using genomic DNA extracted from peripheral blood by the phenol method. Ten subjects had the A1/A2 genotype, eleven subjects had the A2/A2 genotype, and no subject had the A1/A1 genotype. The domain size, including the thalamus and basal ganglia that were inside each side of the putamens, did not differ between the three groups (the A1/A2-group, the A2/A2-group, and the young healthy person group). In the comparison based on this domain, the temporal lobe tended to narrow in the A2/A2-group compared to the A1/A2-group (P = .06). The other domain (cerebrum, corpus callosum, etc.) showed no difference between the A1/A2-group and the A2/A2-group. It is suggested that in methamphetamine psychosis the TaqI A polymorphism not only regulates prolongation of psychosis symptoms but also influences the form of the temporal lobe.