Photon-Counting Detector CT: Potential for 75% Reduction in Contrast Medium Amount: A Phantom Study.

This study aimed to evaluate the potential reduction in contrast medium utilization using photon-counting detector computed tomography (PCD-CT). One PCD-CT scan (CT1) and three conventional (non-PCD-CT) CT scans (CT2-CT4) were performed using a multi-energy CT phantom that contained eight rods with different iodine concentrations (0.2, 0.5, 1, 2, 5, 10, 15, and 20 mg/ml). The CT values of the seven groups (CT1 for 40, 50, 60, and 70 keV; and CT2-4) were measured. Noise and contrast-to-noise ratio (CNR) were assessed for the eight rods at various iodine concentrations. CT2 and CT1 (40 keV) respectively required 20 mg/ml and 5 mg/ml of iodine, indicating that a comparable contrast effect could be obtained with approximately one-fourth of the contrast medium amount. The standard deviation values increased at lower energy levels irrespective of the iodine concentration. The CNR exhibited a decreasing trend with lower iodine concentrations, while it remained relatively stable across all iodine levels (40-70 keV). This study demonstrated that virtual monochromatic 40 keV images offer a similar contrast effect with a reduced contrast medium amount when compared to conventional CT systems at 120 kV.

Midline invasion predicts poor prognosis in diffuse hemispheric glioma, H3 G34-mutant: an individual participant data review.

INTRODUCTION: Diffuse hemispheric glioma, H3 G34-mutant (DHGs), is a newly categorized tumor in pediatric-type diffuse high-grade gliomas, World Health Organization grade 4, with a poor prognosis. Although prognostic factors associated with genetic abnormalities have been reported, few reports have examined the clinical presentation of DHGs, especially from the viewpoint of imaging findings. In this study, we investigated the relationship between clinical factors, including imaging findings, and prognosis in patients with DHGs. METHODS: We searched Medline through the PubMed database using two search terms: "G34" and "glioma", between 1 April 2012 and 1 July 2023. We retrieved articles that described imaging findings and overall survival (OS), and added one DHG case from our institution. We defined midline invasion (MI) as invasion to the contralateral cerebrum, brainstem, corpus callosum, thalamus, and basal ganglia on magnetic resonance imaging. The primary outcome was 12-month survival, estimated using Kaplan-Meier curves and logistic regression. RESULTS: A total of 96 patients were included in this study. The median age was 22 years, and the proportion of male patients was 48.4%. Lesions were most frequently located in the frontal lobe (52.6%). MI was positive in 39.6% of all patients. The median OS was 14.4 months. Univariate logistic regression analysis revealed that OS was significantly worse in the MI-positive group compared with the MI-negative group. Multivariate logistic regression analysis revealed that MI was an independent prognostic factor in DHGs. CONCLUSIONS: In this study, MI-positive cases had a worse prognosis compared with MI-negative cases. PREVIOUS PRESENTATIONS: No portion of this study has been presented or published previously.

Evaluation of the ear ossicles with photon-counting detector CT.

Recently, computed tomography with photon-counting detector (PCD-CT) has been developed to enable high-resolution imaging at a lower radiation dose. PCD-CT employs a photon-counting detector that can measure the number of incident X-ray photons and their energy. The newly released PCD-CT (NAEOTOM Alpha, Siemens Healthineers, Forchheim, Germany) has been in clinical use at our institution since December 2022. The PCD-CT offers several advantages over current state-of-the-art energy-integrating detector CT (EID-CT). The PCD-CT does not require septa to create a detector channel, while EID-CT does. Therefore, downsizing the anode to achieve higher resolution does not affect the dose efficiency of the PCD-CT. CT is an indispensable modality for evaluating ear ossicles. The ear ossicles and joints are clearly depicted by PCD-CT. In particular, the anterior and posterior legs of the stapes, which are sometimes unclear on conventional CT scans, can be clearly visualized. We present cases of congenital anomalies of the ossicular chain, ossicular chain dislocation, tympanosclerosis, and cholesteatoma in which PCD-CT was useful. This short article reports the usefulness of PCD-CT in the 3D visualization of the ear ossicles.

A Case of Migration of a Hydrogel Spacer for Radiotherapy into the Pulmonary Artery.

A 67-year-old man was referred to our hospital for the diagnosis and treatment of prostate cancer. Multidisciplinary discussion led to intensity-modulated radiotherapy preceded by hormone therapy. Before radiotherapy, a biodegradable hydrogel spacer (HS) was placed between the prostate and rectum to reduce radiation injury risk. Three weeks postplacement, pelvic magnetic resonance imaging revealed HS migration into the pelvic vein. Subsequent whole-body contrast-enhanced computed tomography (CECT) revealed HS migration into the pulmonary artery. The patient showed no symptoms or clinical signs. Radiotherapy was completed uneventfully. Complete absorption of the migrated HS was confirmed using CECT images 5 months postplacement.

A Rare Case of Idiopathic Spinal Cord Herniation Treated by DuraGen® Collagen Matrix Graft.

We report a rare case of idiopathic spinal cord herniation (ISCH) with a history of cerebrospinal fluid (CSF) leakage. ISCH is a protrusion of the spinal cord through a dural defect. Thin constructive interference in steady-state (CISS) images clearly demonstrated the herniated cord in the present case. The myelopathy worsened and the patient underwent surgery for reduction of herniated spinal cord; the dural defect was filled by placing collagen matrix graft (DuraGen®) between the inner and outer dural layers. The patient's symptoms have improved without relapse for 8 months since surgery. This method may be a good surgical option for cases of spinal cord herniation.

MRI multiparametric scoring system for pial blood supply of intracranial meningiomas.

Background: Meningiomas are occasionally fed by pial blood supply (PBS). It is postulated that peritumoral flow void (PTFV), peritumoral brain edema (PTBE), and absence of an arachnoid plane (AP) are useful parameters for evaluating PBS. Purpose: To determine whether conventional magnetic resonance imaging (MRI) using a multiparametric scoring system (MSS) is a useful way to predict PBS. Material and Methods: Forty-six patients were included and divided: PBS and non-PBS groups. Differences between the groups in six parameters of MR imaging were analyzed: tumor size, tumor location, PTBE grade, AP grade, PTFV, and MIB1 labeling index (MIB1-LI) grade. Cutoff values were determined using receiver operating characteristic (ROC) curve analysis for the differentiation of both groups based on statistically significant parameters. All cases were scored as 1 (PBS) or 0 (non-PBS) for each parameter according to set thresholds. Individual scores were totaled for each case, yielding a combined score for each case to obtain a cutoff value using ROC curve analysis for the MSS. Results: Peritumoral brain edema grade, AP grade, PTFV, and MIB-LI grade were statistically associated with PBS. Receiver operating characteristic curve analyses showed that PTBE grade 3 or 4, AP grade 3 or 4, and PTFV positivity had the highest accuracy of 69%, 64%, and 68%, respectively. Regarding the MSS, a cutoff value of 2 had the highest accuracy of 71%; PBS diagnosis was indicated by at least two of the three parameters, namely, PTBE grade, AP grade, and PTFV. Conclusion: The MSS is a useful way to predict PBS in intracranial meningiomas on MRI.

Association between Histological Types and Enhancement of Dynamic CT for Primary Lung Cancer.

The aim of this study was to explore enhancement patterns of different types of primary lung cancers on 2-phase dynamic computed tomography (CT). This study included 217 primary lung cancer patients (141 adenocarcinomas [ADs], 48 squamous cell carcinomas [SCCs], 20 small cell lung carcinomas [SCLCs], and 8 others) who were examined using a 2-phase dynamic scan. Regions of interest were identified and mean enhancement values were calculated. After excluding the 20 SCLCs because these lesions had different clinical stages from the other cancer types, the mean attenuation values and subtractions between phases were compared between types of non-small cell lung carcinomas (NSCLCs) using the Kruskal-Wallis test. Late phase attenuation and attenuation of the late minus unenhanced phase (LMU) of SCCs were significantly higher than those of ADs (p<0.05). To differentiate SCC and AD in the late phase, a threshold of 80.21 Hounsfield units (HU) gave 52.9% accuracy. In LMU, a threshold of 52.16 HU gave 59.3% accuracy. Dynamic lung CT has the potential to aid in differentiating among NSCLC types.

Reduction of neuromelanin-positive nigral volume in patients with MSA, PSP and CBD.

OBJECTIVE: Diseases presenting extrapyramidal symptoms are accompanied by nigral cell loss. In the previous study, we demonstrated the reduction of the neuromelanin-positive volume of substantia nigra (SN) pars compacta (SNc) in patients with Parkinson's disease (PD) using 3-Tesla MRI. In the present study we investigated the neuromelanin-positive SNc volume in patients with the other parkinsonian disorders including multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) and compared the results with those with PD, spinocerebellar ataxia (SCA) and controls. PATIENTS AND METHODS: Axial T1-weighted (T1W) images were obtained with a 3-Tesla MRI scanner. The border of the neuromelanin-positive region of the SNc was traced manually on these images with a pentablet pointing device and the SNc volume was calculated. The SNc volumes of 28 patients with MSA, 11 patients with PSP and 10 patients with CBD were compared with those of 80 patients with PD, 9 patients with SCA and 54 patients who had suffered mild acute ischemic stroke as controls. The mean volumes for the left and right SN were used for statistical analyses. RESULTS: The volumes of the neuromelanin-positive SNc region in patients with MSA, PSP and CBD, but not SCA were reduced to the same extent as PD patients compared with controls. CONCLUSION: Reduced volume of the neuromelanin-positive SNc region of patients with MSA, PSP and CBD was detected by neuromelanin MR imaging. Volumetric evaluation of neuromelanin MR imaging may provide a biomarker of nigral degeneration in patients with MSA, PSP and CBD as in patients with PD.

Neuromelanin magnetic resonance imaging of nigral volume loss in patients with Parkinson's disease.

Parkinson's disease (PD) is characterized by progressive degeneration of melanin-containing neurons in the substantia nigra pars compacta (SNc). Pathological change has not been detected by neuroimaging techniques in patients with PD in vivo. We examined 80 patients with PD to determine whether degeneration of the SNc is detectable in vivo by MRI. The age-matched controls consisted of 54 patients who had suffered mild acute ischemic stroke. Axial T1-weighted MRI were obtained with a 3-Tesla MRI scanner. The border of the neuromelanin-sensitive region in the SNc was traced manually on these images, and the volume of this area was calculated. The mean volumes for the left and right SNc were significantly reduced in patients with PD compared to the controls. Volume loss became marked in parallel with disease severity and duration. Neuromelanin MRI may be considered as a biomarker of nigral degeneration in patients with PD.

Preliminary retrospective investigation of FDG-PET/CT timing in follow-up of ablated lung tumor.

OBJECTIVE: The aim of this study was to clarify the most appropriate follow-up initiation time point for positron emission tomography (PET)/computed tomography (CT) following radio frequency ablation (RFA) of lung tumors, and the cutoff values of maximum standard uptake value (SUV(max)) to evaluate local tumor progression. METHODS: We enrolled 15 patients (8 men, median age 62 years) with 60 tumors, who were treated with RFA of lung tumors and underwent fluorodeoxyglucose (FDG)-PET/CT following RFA. Local tumor progression was assessed by periodic chest CT images prior to and following intravenous administration of a contrast medium. The SUV(max) of three periods, namely, 0-3 months, 3-6 months, and 6-9 months after RFA, was evaluated. The appropriate time point for follow-up initiation and the cutoff value of SUV(max) were determined using receiver-operating characteristic (ROC) analysis. RESULTS: The median follow-up period was 357 days. Of 60 tumors, 10 showed local progression. The area under the ROC curve (Az) for the 6-9 months (P = 0.044) was the largest and almost equal to that of the 3-6 months (P = 0.024). Az for the 0-3 months was the smallest and statistically insignificant (P = 0.705). The cutoff value of 1.5 of SUV(max) at 3-9 months after RFA showed 77.8% sensitivity and 85.7-90.5% specificity. CONCLUSIONS: The appropriate follow-up initiation time point is at least 3 months following RFA. Thus, SUV(max) is a useful and reliable predictive indicator.

Factors predictive of survival after percutaneous endoscopic gastrostomy in the elderly: is dementia really a risk factor?

OBJECTIVES: Outcomes, especially survival, after percutaneous endoscopic gastrostomy (PEG) in patients with dementia remain unclear. The aims of this study were to assess the impact of dementia on survival after PEG and to explore the risk factors in elderly patients. METHODS: A total of 311 consecutive Japanese patients who underwent PEG were enrolled in this retrospective cohort study. Dementia was defined according to the standard criteria. After the clinical characteristics of patients with and without dementia were compared, the Kaplan-Meier method and Cox proportional-hazards regression analysis were applied to analyze survival rates. RESULTS: Survival was not significantly different between the two groups. The 12-month survival rate of patients with dementia (N = 143) was 51%, and that of patients without dementia (N = 168) was 49%. More than 20% of patients with dementia lived more than 3 yr after PEG. The predictors of poor survival after PEG were previous subtotal gastrectomy (odds ratio [OR] 2.619, 95% confidence interval [CI] 1.367-5.019), serum albumin <2.8 g/dL (OR 2.081, 95% CI 1.490-2.905), age >80 yr (OR 1.721, 95% CI 1.234-2.399), chronic heart failure (OR 1.541, 95% CI 1.096-2.168), and male gender (OR 1.407, 95% CI 1.037-1.909). CONCLUSIONS: In our series, there was no evidence to support a poorer prognosis after PEG in elderly people with dementia compared with the cognitively preserved elderly. However, if patients are male or of advanced age, have a low serum albumin, chronic heart failure, or subtotal gastrectomy, physicians should inform families that a poor prognosis is expected before performing PEG.

Old-fashioned but modern tube cervical esophagostomy.

BACKGROUND: Nasogastric tubes (NGT) are used widely for feeding and decompressions of stomach, but they are associated with several complications and discomfort. When prolonged use of NGT is required, percutaneous endoscopic gastrostomy (PEG) should be considered. However, PEG is not feasible for patients with previous gastrectomy. We have performed tube cervical esophagostomy (TCE) for such difficult cases of PEG. METHODS: The current study focused on 7 patients requiring TCE for feeding or decompression from 2004 to 2005 at Tottori Municipal Hospital in Japan. RESULTS: The procedure is relatively simply to perform under local anesthesia and significant complications were not experienced. CONCLUSIONS: Feeding or decompressive TCE is useful alternative procedure in patients where PEG is not feasible or unacceptable.