Evaluating Hip Periprosthetic Joint Infection with Metal-artifact-reduction MR Imaging.

PURPOSE: To evaluate the significant findings of hip periprosthetic joint infection (PJI) using metal-artifact-reduction (MAR) MRI and to compare the MRI results to other clinical markers. METHODS: The results of MRI, including two-dimensional fast-spin echo sequences with increased bandwidth and multi-acquisition variable-resonance image combination selective for hips with orthopedic implants at 1.5T (from April 2014 to November 2021), were retrospectively assessed for imaging findings and diagnostic impressions by two radiologists. Clinical data and courses were also investigated. Univariate and multivariate analyses were performed to identify the significant MRI findings in patients with hip PJI and those who underwent surgical intervention. The MRI impressions were compared with other clinical markers in diagnosing hip PJI. RESULTS: Thirty-seven hip joints in 24 Asian patients (age = 73.9 ± 10.8 years; 18 females) were included. Twelve hip joints (32%) had PJI; seven underwent a surgical intervention. The significant findings for hip PJI included periosteal edema of the acetabulum, intermuscular edema, intramuscular fluid collection, and lymphadenopathy (P < 0.05). In the cases with surgical intervention, the significant findings included capsular distension, capsular thickening, an osteolysis-like pattern of the femur, subcutaneous fluid collection, and lymphadenopathy (P < 0.05). The MRI impressions had high diagnostic significance for both hip PJI cases and those with surgical intervention (P < 0.001). The MRI impression was more significant for hip PJI than the other clinical markers (P < 0.05), while the other clinical markers were more significant in the cases with surgical intervention (P < 0.05). CONCLUSION: The significant findings in the hip PJI cases included acetabular periosteal edema, intermuscular edema, intramuscular fluid collection, and lymphadenopathy. The significant findings in the cases with surgical intervention included capsular distention, capsular thickening, a femoral osteolysis-like pattern, subcutaneous fluid collection, and lymphadenopathy. The utilization of MAR MRI demonstrated great diagnostic significance for hip PJI.

[Improved Protective Equipment for NICU Portable Radiography].

We have been developing protective equipment for portable radiography in neonatal intensive care units because the portable radiography's X-ray tube is in close proximity to the head of the nurse who is assisting the patient. Although our initial protective-equipment design was highly effective, there were some concerns that it obstructed the view of the patient and was difficult to handle. To overcome this problem, we have developed two new types of protective device: a narrow-type 0.13 mmPb device, 17 cm long and 45 cm wide (weight 200 g); and a wide type with a wider core material, 45 cm long and 25 cm wide (weight 300 g), both of which can be hung from the collimator cover of mobile X-ray equipment. The measured protective effectiveness was 80.6% at head height for the wide type and 76.8% for the narrow type. A survey of nurses regarding the new protective devices revealed no significant differences between the two types in terms of visibility and whether the devices would be an obstacle when assisting patients. The nurses preferred the wider type, which offered better protection. Radiological technologists also liked that both types were easy to handle because the irradiation field could be adjusted even after the device was fitted. Both types of the new protective device are thus expected to be useful in clinical practice in terms of their high protective effect and improved ease of handling.

[Creation of Protective Equipment for Portable Radiography in Neonatal Intensive Care Unit].

Portable imaging in the NICU requires the assistance of a nurse, and the nurse is in close proximity to the X-ray tube, In all, 64 percent of our nurses thought that additional protective equipment was needed. Therefore, a radiation protection device was created and its usefulness was verified. A protective equipment of 0.13 mmPb with a width of 38 cm and a length of 70 cm was made and hung from the mono-tank X-ray unit of the mobile X-ray unit. The position of the nurse was set at 30 cm outward from the center of the irradiation field, and the protective effect was measured at three points: (a) the patient's height, (b) 30 cm above the patient, and (c) 60 cm above the patient. For the imaging conditions, a 2-liter plastic bottle filled with water was placed in the incubator, and measurements were taken with an SID of 100 cm, irradiated field of 20.3 cm×25.4 cm, tube voltage of 58 kV, and tube current-time product of 10 mAs, which was converted to the actual imaging condition of 1 mAs. Based on the results obtained, a questionnaire survey was conducted on nurses' thoughts for the protective equipment created for them. Only 3% reduction in height of (a) where no protective equipment is reached but (b) 50% and (c) 92%, respectively. In all, 82 percent of the nurses had a favorable impression of the new protective equipment. It is expected that the protective equipment designed to control lens dose and reduce anxiety of nurses will be useful.

Feasibility of the fat-suppression image-subtraction method using deep learning for abnormality detection on knee MRI.

Purpose: To evaluate the feasibility of using a deep learning (DL) model to generate fat-suppression images and detect abnormalities on knee magnetic resonance imaging (MRI) through the fat-suppression image-subtraction method. Material and methods: A total of 45 knee MRI studies in patients with knee disorders and 12 knee MRI studies in healthy volunteers were enrolled. The DL model was developed using 2-dimensional convolutional neural networks for generating fat-suppression images and subtracting generated fat-suppression images without any abnormal findings from those with normal/abnormal findings and detecting/classifying abnormalities on knee MRI. The image qualities of the generated fat-suppression images and subtraction-images were assessed. The accuracy, average precision, average recall, F-measure, sensitivity, and area under the receiver operator characteristic curve (AUROC) of DL for each abnormality were calculated. Results: A total of 2472 image datasets, each consisting of one slice of original T1WI, original intermediate-weighted images, generated fat-suppression (FS)-intermediate-weighted images without any abnormal findings, generated FS-intermediate-weighted images with normal/abnormal findings, and subtraction images between the generated FS-intermediate-weighted images at the same cross-section, were created. The generated fat-suppression images were of adequate image quality. Of the 2472 subtraction-images, 2203 (89.1%) were judged to be of adequate image quality. The accuracies for overall abnormalities, anterior cruciate ligament, bone marrow, cartilage, meniscus, and others were 89.5-95.1%. The average precision, average recall, and F-measure were 73.4-90.6%, 77.5-89.4%, and 78.4-89.4%, respectively. The sensitivity was 57.4-90.5%. The AUROCs were 0.910-0.979. Conclusions: The DL model was able to generate fat-suppression images of sufficient quality to detect abnormalities on knee MRI through the fat-suppression image-subtraction method.

[Usefulness of Radiation Protection Cloths in Fluoroscopy with Clean Areas].

Lowering the dose limit for the lens of the eye incorporated into the Regulation on Prevention of Ionizing Radiation Hazards, effective on April 2021, and dose reduction will become more and more important in the field of radiation. Radiation protective cloth is used as a protective equipment in fluoroscopy rooms. Although it is usually used to protect staff from radiation exposure during endoscopic retrograde cholangiopancreatography, we investigated whether there is a way to use it for procedures in clean areas. Assuming ureterostomy fistula replacement in urology, the protective cloth was suspended on the side of the patient's head and posterior aspect of the tube, and the distance between the anterior aspect of the X-ray tube and the patient's foot was 55 cm. As a result of measuring the dose rate, a 10% dose reduction was obtained for the lens of the eye of the surgeon, and the distribution of air dose rate in the examination room was significantly reduced. Although scattered radiation from the radiation protection cloth appeared in some areas, the radiation dose to the patient was reduced throughout the body, and a high degree of radiation protection was obtained, especially for the lens of the eye. It is expected that the radiation protection cloths may be useful even when the length of the cloths is limited due to the cleanliness of the area.

Diagnostic Value of Advanced Metal Artifact Reduction Magnetic Resonance Imaging for Periprosthetic Joint Infection.

MATERIALS AND METHODS: Magnetic resonance imaging around metal joint prostheses including multiacquisition variable-resonance image combination selective at 1.5 T (from April 2014 to August 2020) was retrospectively evaluated by 2 radiologists for detection of abnormal findings (joint effusion, capsular thickening, pericapsular edema, soft-tissue fluid collection, soft-tissue edema, bone marrow edema pattern around the implant [BME pattern], lymphadenopathy, and others) and overall image impression for PJI. Regarding the soft-tissue fluid collection, presence of communication to the joint or capsular-like structure was evaluated. Clinical assessments were recorded. Positive predictive values (PPVs), negative predictive values (NPVs), and odds ratios (ORs) for PJI were calculated for the abnormal findings. Overall image impression for PJI was evaluated. χ2, Fisher exact, t, and Mann-Whitney U tests and receiver operating characteristic analysis were used. Interobserver agreement was assessed with κ statistics. RESULTS: Forty-three joints in 36 patients (mean ± SD age, 75.4 ± 8.8 years; 30 women; hip [n = 29], knee [n = 12], and elbow [n = 2]) were evaluated. Eighteen joints (42%) were clinically diagnosed as PJI. The findings suggesting PJI were capsular thickening (PPV, 70%; NPV, 90%; OR, 20.6), soft-tissue fluid collection (PPV, 81%; NPV, 81%; OR, 19.1), soft-tissue edema (PPV, 67%; NPV, 89%; OR, 17), pericapsular edema (PPV, 76%; NPV, 81%; OR, 13.7), and joint effusion (PPV, 55%; NPV, 100%; OR, 12). Soft-tissue fluid collection without capsular-like structure (PPV, 83%; NPV, 74%; OR, 14.4) or with communication to the joint (PPV, 75%; NPV, 71%; OR, 7.3) suggested PJI. The combinations of joint effusion, capsular thickening, pericapsular edema, soft-tissue fluid collection, and soft-tissue edema highly suggested PJI. Regarding the BME pattern, the combination with soft-tissue edema raised the possibility of PJI (PPV, 73%; NPV, 69%; OR, 5.9). Regarding the interobserver agreements for each abnormal finding, κ values were 0.60 to 0.77. Regarding the overall image impression, weighted κ value was 0.97 and areas under the receiver operating characteristic curve were 0.949 (95% confidence interval, 0.893-1.005) and 0.926 (95% confidence interval, 0.860-0.991) with no significant difference (P = 0.534). CONCLUSIONS: The findings suggesting PJI were capsular thickening, soft-tissue fluid collection, soft-tissue edema, pericapsular edema, and joint effusion. The combinations of them highly suggested PJI. Regarding the BME pattern, the combination with soft-tissue edema raised the possibility of PJI.

[Comparison of Frontal and Lateral Measurements of Bone Mineral Density of the Lumbar Spine with Dual-energy X-ray Absorptiometry (DXA) in Spinal Deformity: a Phantom Study].

The bone mineral density (BMD) measurement of the lumbar spine with dual-energy X-ray absorptiometry (DXA) has the advantage of being able to detect early changes in BMD, which is usually used for the evaluation of drug therapy. However, DXA is not considered suitable for spinal deformity because it is a two-dimensional measurement. The aims of this study were to compare frontal and lateral measurements with a phantom and to examine the possibility of the evaluation of lumbar spine BMD in spinal deformity. The values of frontal and lateral measurements were compared when the lumbar phantom was tilted by 10 degrees from 0 to 40 degrees, assuming kyphosis, and when it was tilted by 5 degrees from 0 to 10 degrees to the right and left, assuming scoliosis. We revealed that in the case of kyphosis, the frontal is more accurate, and in the case of scoliosis, the lateral is more accurate; small rotation of subjects on the plane parallel to the image receiving surface could be acceptable. In general, the two-directional BMD measurement is useful for the improvement of the accuracy and may have a potential to measure patients with spinal deformity, which was previously thought to be impossible.

Refractory and Severe Hepatogenous Diabetes in a Patient with Cirrhosis Improved by Balloon-Occluded Retrograde Transvenous Obliteration of a Large Portosystemic Shunt.

A 54-year-old male with liver cirrhosis (Child-Pugh score 5) presented with severe hepatogenous diabetes (HbA1c 12.6%). Contrast-enhanced CT showed a large portosystemic shunt from the inferior mesenteric vein to the left internal iliac vein. Glucose monitoring showed postprandial hyperglycemia and reactive hypoglycemia. After balloon-occluded retrograde transvenous obliteration (BRTO) and partial splenic transarterial embolization, postprandial hyperglycemia was diminished. Seven months later, HbA1c had improved from 12.6% to 6.7%. In this case, postprandial hyperglycemia occurred by direct delivery of glucose into the systemic circulation via the shunt, and fasting hypoglycemia occurred during treatment with oral antidiabetic agents and insufficient gluconeogenesis. BRTO of the portosystemic shunt resulted in improvement in hepatogenous diabetes.

Unexpected discovery of a diffuse astrocytoma of the conus medullaris in an elderly NF1 patient.

Neurofibromatosis type 1 (NF1) is one of the most common genetic neurocutaneous disorders, and it is well known to be associated with peripheral or central nervous system malignancies. The most common malignant tumors are malignant peripheral nerve sheath tumors (MPNSTs); MPNSTs are the most common cause of death in patients with NF1. Central nervous system malignancies rarely occur. So far, the occurrence of spinal cord malignancies is exceedingly rare. Herein, we report a rare case of a 69-year-old male with NF1 following tumor resection twice for cutaneous MPNSTs developing intramedullary diffuse astrocytoma in the conus medullaris, which initially presented with traumatic spinal cord injury associated with a compression fracture from fall. Contrast-enhanced magnetic resonance imaging and biopsy of the spinal cord were required to establish the final diagnosis.

Osteointegration of a Biocomposite Suture Anchor After Arthroscopic Shoulder Labral Repair.

PURPOSE: To evaluate osteoconductivity of a poly-L-lactide co-glycolide (PLG)-calcium sulfate (CS)-ß-tricalcium phosphate (ß-TCP) biocomposite suture anchor after arthroscopic shoulder labral repair. METHODS: The subjects of this study were patients who participated in a clinical trial for acquisition of marketing approval of a PLG-CS-ß-TCP biocomposite anchor in Japan. They underwent arthroscopic labral repair using the anchor, and computed tomographic (CT) images of the glenoid were obtained 2 years after surgery. Osteoconductivity at the anchor sites was evaluated with the CT images using the established ossification quality score. Shoulder function scores including the Rowe score and Japanese Shoulder Society shoulder instability score were also assessed 2 years after surgery. RESULTS: CT images and functional scores were obtained from 37 patients, comprising 29 men and 8 women with a mean age of 29 years (range, 25-33 years) at surgery. A total of 148 anchors were implanted in the 37 shoulders. Osteoconductivity was seen in 133 of 148 anchor sites (90.0%) 2 years after implantation. No significant differences in osteoconductivity were found by anchor diameter or position. The Rowe score significantly improved from 39.9 points (95% confidence interval [CI], 33.8-45.9 points) preoperatively to 96.6 points (95% CI, 95.1-98.1 points) at 2 years postoperatively (P < .001). The Japanese Shoulder Society shoulder instability score also significantly improved, from 63.1 points (95% CI, 58.4-67.7 points) preoperatively to 96.3 points (95% CI, 94.7-97.8 points) at 2 years postoperatively (P < .001). CONCLUSIONS: Biocomposite suture anchors made of PLG, CS, and ß-TCP exhibited some osteoconductivity 2 years after arthroscopic labral repair, as well as good clinical outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Transient Ischemic Attack: Which Determines Diffusion-Weighted Image Positivity?

AIM OF THE STUDY: Diffusion-weighted image (DWI) of magnetic resonance imaging (MRI) can reveal high signal lesion in up to 50% of transient ischemic attack (TIA) patients. However, it is not well-known which factors determine developing DWI positivity. In order to answer this question, we analyzed factors relevant to DWI positivity in TIA patients. METHODS: We had 257 stroke patients at a university emergency/neurology wards. They were 140 men, 117 women, mean age 72 (45-88) years. Among them, 24 (9.3%) had TIA (14 men, 10 women, mean age 71 [58-82] years). All patients underwent a 1.5T MRI. In 24 TIA patients, we investigated the following parameters in relation with stroke maturation: ABCD2 score, smoking habits, blood profile, HbA1C, dyslipidemia, coagulation factors, carotid echography, electrocardiography, cardiac echography, chest X-ray, neurological symptom/signs, imaging, and recurrence of neurological symptom on follow-up. RESULTS: In 24 TIA patients, 13 (54%) were DWI positive and 11 (46%) were DWI negative. After an extensive analysis, all parameters were not relevant to DWI positivity except for plasma osmolarity, i.e., plasma osmolarity in DWI positive cases (305.3 mOsm/l) is significantly higher than that in DWI negative cases (301.3 mOsm/l) (P = .0064). As for recurrence, 4 of 24 TIA patients recurred. They were 1 (9.0%) of 11 DWI negative cases and 3 (23.1%) of 13 DWI positive cases. Therefore, DWI positive cases recurred more frequently than DWI negative cases did, although it did not reach statistical significance. CONCLUSIONS: TIA with DWI positivity in our institute was 54%, closely associated with initial dehydration and might predict stroke recurrence.

MIBG Myocardial Scintigraphy Identifies Premotor PD/DLB During a Negative DAT Scan Period: Second Report.

OBJECTIVES: Neuroimaging markers for Parkinson's disease (PD)/dementia with Lewy bodies (DLB) include dopamine transporter (DAT) scanning and metaiodobenzylguanidine (MIBG) myocardial scintigraphy. It is unknown which marker is useful to identify the premotor phase PD/DLB. We reported four patients who, during a negative DAT scan period, had a positive MIBG result that suggested premotor PD/DLB. Here we report 18 additional patients. METHODS: This study was a prospective cohort study. The recruiting period was five years; prospective follow-up period, 5.5 ± 3.0 years; and a once a year (minimum) follow-up visit. We recruited 745 referred subjects. The inclusion criteria were having at least one of the following known PD nonmotor features: (1) autonomic: postural hypotension (pure autonomic failure [PAF]), constipation, bladder dysfunction; (2) sleep: REM sleep behavior disorder (RBD); and (3) cognitive: mild cognitive impairment or psychiatric symptoms. Also, the patient had to have undergone both DAT and MIBG tests. RESULTS: Only 18 patients fulfilled these criteria. Their characteristics were: elderly (mean age 75.5 years), with long histories (onset 61.0 years; duration 14.5 years), and predominately male (14 men, four women). The patients' neurologic diagnoses were constipation/RBD in 10, constipation/RBD/PAF in six, and constipation/PAF in two. During the follow-up period, seven patients developed PD or DLB. An abnormal MIBG result was noted in 94%, and an abnormal DAT result was noted in 56%. CONCLUSIONS: MIBG has the potential to be a useful marker during the DAT scan negative period to identify premotor PD/DLB, but further studies are needed.

Superior graft maturation after anatomical double-bundle anterior cruciate ligament reconstruction using the transtibial drilling technique compared to the transportal technique.

PURPOSE: To evaluate and compare the femoral tunnel aperture position, graft bending angle and the magnetic resonance imaging (MRI) graft signal intensity after anatomical double-bundle anterior cruciate ligament (ACL) reconstruction between transtibial and transportal drilling techniques of the femoral tunnel. METHODS: Eighty-seven patients who underwent anatomic double-bundle ACL reconstruction with hamstring tendon autograft between January 2012 and December 2014 were included in this retrospective study. Forty-one patients underwent reconstruction using a transportal technique (TP group) and 46 patients underwent reconstruction using a transtibial technique (TT group). The anteromedial (AM) femoral aperture position and the graft bending angle were assessed using transparent three-dimensional CT 2 weeks postoperatively. MRI assessment was performed with proton density-weighted images in an oblique coronal plane 6 and 12 months postoperatively. Signal/noise quotient was calculated for two specific graft sites (femoral tunnel site and mid-substance site). Femoral aperture position, the graft bending angle and signal/noise quotient were compared between the TP and TT groups. RESULTS: There was no significant difference in the aperture position between the two groups. The graft bending angle of the AM tunnel in the axial plane was significantly greater in the TP group (p < 0.001). On the other hand, the TP group had a significantly more acute angle in the coronal plane (p < 0.001). There was no significant difference at either site in the signal/noise quotient of the graft between the two groups at 6 months. However, the TT group had a lower signal/noise quotient at 12 months at both sites (femoral aperture: p = 0.04, mid-substance: p = 0.004). CONCLUSION: There was a significant difference in signal/noise quotient between the two drilling techniques 12 months postoperatively. There was no significant difference in femoral tunnel aperture position between the two groups. However, graft bending angle at the femoral tunnel aperture was significantly different between the two groups, indicating the possibility that graft bending angle is a factor that influences graft maturation. This indicates that the TT technique has an advantage over the TP technique in terms of graft maturation.

Quantitative evaluation of the relative apparent diffusion coefficient values on multiparametric magnetic resonance imaging to predict higher Gleason score prostate cancer.

INTRODUCTION: Apparent diffusion coefficient (ADC) values on multiparametric magnetic resonance imaging (mpMRI) have been reported to correlate with high-Gleason score (GS) prostate cancer. However, the relative ADC values between tumor lesions and normal tissue have been suggested as more suitable than the absolute ADC values for evaluation of diffusion abnormalities, because absolute ADC values are susceptible to differences in scanners or scanner settings. The present study evaluated the usefulness of the relative assessment of ADC values between tumor lesions and normal tissue on preoperative mpMRI for the prediction of high-risk prostate cancer on radical prostatectomy specimens. MATERIALS AND METHODS: A retrospective analysis of 48 men who underwent radical prostatectomy between January 2013 and December 2014 was conducted. MpMRI was performed with a 3.0-T scanner using b-values of 0 and 1500 s/mm2. ADC values of the tumor (ADCTUMOR) and normal prostate and the relative ADC tumor/normal ratio (ADCTNR) were evaluated by two radiologists. RESULTS: The inter-rater reliability between two radiologists for ADCTUMOR measurement was high, with Pearson's r = 0.982. There was no difference in ADCTUMOR between GS ≤7 and GS ≥8. In contrast, ADCTNR was significantly lower in GS ≥8 than in GS ≤7. ROC curves of ADCTNR to predict higher GS (≥8) showed better classification performance (AUC = 0.8243, p = .0012 by radiologist A and AUC = 0.7961, p = .0031 by radiologist B) than of ADCTUMOR. CONCLUSIONS: The relative assessment of ADC values between tumor lesions and normal tissue could improve the detection rate of high-risk prostate cancers.

Young-Onset Dementia with Lewy Bodies.

Young-onset (< 65 years) dementia is a challenging clinical problem. A 61-year-old man visited our clinic because of a 2-year history of mild cognitive impairment of the executive disorder type. He was initially suspected of having young-onset Alzheimer's disease due to the lack of motor signs or hippocampal atrophy by conventional brain MRI. However, he proved to have anosmia, erectile dysfunction, hypersexuality, constipation, REM sleep behavior disorder, and emotional lability; imaging findings included positive brain perfusion SPECT, nigrosome MRI, DAT scan, and MIBG myocardial scintigraphy. All these clinical imaging features led to the correct diagnosis of young-onset dementia with Lewy bodies (YOD-DLB). It is hoped that this case report will help facilitate a future prospective study to diagnose and follow YOD-DLB patients with the aim of determining appropriate management and care.

Genetic Screening for Spinocerebellar Ataxia Genes in a Japanese Single-Hospital Cohort.

OBJECTIVE: Diagnosis of sporadic cerebellar ataxia is a challenge for neurologists. A wide range of potential causes exist, including chronic alcohol use, multiple system atrophy of cerebellar type (MSA-C), and sporadic late cortical cerebellar atrophy. Recently, an autosomal-dominant spinocerebellar ataxia (SCA) mutation was identified in a cohort of patients with non-MSA-C sporadic cerebellar ataxia. The aim of this study is to genetically screen genes involved in SCA in a Japanese single-hospital cohort. METHODS: Over an 8-year period, 140 patients with cerebellar ataxia were observed. There were 109 patients with sporadic cerebellar ataxia (no family history for at least four generations, 73 patients with MSA-C, and 36 patients with non-MSA-C sporadic cerebellar ataxia) and 31 patients with familial cerebellar ataxia. We performed gene analysis comprising SCA1, 2, 3, 6, 7, 8, 12, 17, 31, and dentatorubro-pallidoluysian atrophy (DRPLA) in 28 of 31 non-MSA-C sporadic patients who requested the test. Familial patients served as a control. RESULTS: Gene abnormalities were found in 57% of non-MSA-C sporadic cerebellar ataxia cases. Among patients with sporadic cerebellar ataxia, abnormalities in SCA6 were the most common (36%), followed by abnormalities in SCA1 (7.1%), SCA2 (3.6%), SCA3 (3.6%), SCA8 (3.6%), and DRPLA (3.6%). In contrast, gene abnormalities were found in 75% of familial cerebellar ataxia cases, with abnormalities in SCA6 being the most common (29%). For sporadic versus familial cases for those with SCA6 abnormalities, the age of onset was older (69 years vs. 59 years, respectively), and CAG repeat length was shorter (23 vs. 25, respectively) in the former than in the latter (not statistically significant). CONCLUSION: Autosomal-dominant mutations in SCA genes, particularly in SCA6, are not rare in sporadic cerebellar ataxia. The reason for the frequency of mutations in SCA6 remains unclear; however, the reason may reflect a higher age at onset and variable penetrance of SCA6 mutations.

Diagnostic imaging of dementia with Lewy bodies by susceptibility-weighted imaging of nigrosomes versus striatal dopamine transporter single-photon emission computed tomography: a retrospective observational study.

INTRODUCTION: The characteristics of dementia with Lewy bodies (DLB), Alzheimer's disease (AD) and amnestic mild cognitive impairment (a-MCI) overlap but require different treatments; therefore, it is important to differentiate these pathologies. Assessment of dopamine uptake in the striatum using dopamine transporter (DaT) single-photon emission computed tomography (SPECT) is the gold standard for diagnosing DLB; however, this modality is expensive, time consuming and involves radiation exposure. Degeneration of the substantia nigra nigrosome-1, which occurs in DLB, but not in AD/a-MCI, can be identified by 3T susceptibility-weighted imaging (SWI). Therefore, the aim of this retrospective observational study was to compare SWI with DaT-SPECT for differentiation of DLB from AD/a-MCI. METHODS: SWI data were acquired for patients with clinically diagnosed DLB (n = 29), AD (n = 18), a-MCI (n = 13) and healthy controls (n = 26). Images were analysed for nigrosome-1 degeneration. Diagnostic accuracy was evaluated for DLB, AD and a-MCI compared with striatal dopamine uptake using DaT-SPECT. RESULTS: SWI achieved 90% diagnostic accuracy (93% sensitivity, 87% specificity) for the detection of nigrosome-1 degeneration in DLB and not in AD/a-MCI as compared with 88.3% accuracy (93% sensitivity, 84% specificity) using DaT-SPECT. CONCLUSIONS: SWI nigrosome-1 evaluation was useful in differentiating DLB from AD/a-MCI, with high accuracy. This less invasive and less expensive method is a potential alternative to DaT-SPECT for the diagnosis of DLB.