Acute Fatty Liver of Pregnancy Complicated With Mild Encephalitis/Encephalopathy With a Reversible Splenial Lesion: A Case Report.

Acute fatty liver of pregnancy (AFLP) is a rare complication of pregnancy that may result in fulminant hepatic failure. A 28-year-old woman, at 36 weeks of gestation, presented to a maternal-fetal outpatient clinic with fever and headache. She was prescribed analgesics and was planned for follow-up. Two days later, she was taken back for evaluation by her husband to the previous physician again because of the subacute onset of impaired consciousness. Blood tests showed a marked elevation of liver enzymes and C-reactive protein (CRP), and the patient was transported to a tertiary hospital. A clinical diagnosis of AFLP or hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome was made, and an emergency cesarean section was performed. Unconsciousness was prolonged due to mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) for three days. A liver biopsy was performed on postoperative day 11. Liver biopsy results showed large and small droplet fatty deposits, and the diagnosis of AFLP was confirmed. Thereafter, the elevated liver enzymes resolved spontaneously solely by supportive care. The patient presented with symptoms of impaired consciousness due to mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), which led to a visit to a tertiary hospital and early intervention for AFLP. This case suggested that there may be similarities between the two pathologies of AFLP and MERS.

Ovarian torsion due to ovarian hyperstimulation syndrome diagnosed by sonographic whirlpool sign in the first trimester of pregnancy: A case report.

Ovarian torsion during pregnancy is a rare condition that needs prompt diagnosis and detorsion in order to preserve ovarian function. Diagnosing ovarian torsion is a difficult procedure especially in pregnant cases since radiation exposure should be avoided. Detecting the whirlpool sign by ultrasonography is a highly useful technique as it is noninvasive, less time-consuming, and radiation-free. Here is a case of ovarian torsion due to ovarian hyperstimulation syndrome diagnosed solely by sonographic features and in which laparoscopic detorsion was promptly performed. A 26-year-old woman in her sixth week of pregnancy visited a tertiary hospital with sudden onset lower abdomen pain. Transvaginal ultrasound detected an 8 cm left ovary and a whirlpool sign between the uterus and left ovary. Ovarian torsion was suspected and laparoscopic surgery was performed. Intraoperatively, an enlarged left ovary was twisted at 540° involving the left fallopian tube. After detorsion, bilateral ovaries were preserved and the postoperative course was uneventful. Ovarian torsion was suspected solely by ultrasonographic features which led to surgical detorsion quickly, resulting in the preservation of bilateral ovaries. Detecting the whirlpool sign when ovarian torsion is suspected is useful, especially in pregnant women.

Step-by-step instructions for detecting whirlpool sign in adnexal torsion.

Objective: Adnexal torsion is a common gynecological emergency whose prompt diagnosis is essential because a delay may lead to ovarian dysfunction. Although the whirlpool sign is reliable for diagnosing ovarian cyst torsion, technical difficulties hinder its use by sonographers. Here we developed a systematic approach to visualizing this sign by focusing on the fact that torsion arises from the space between the uterus and the pelvic wall. One must determine the origin of the torsion via transverse imaging of the uterus and follow the twisted ligaments to the ovarian cyst. Patients and Methods: Two women aged 56 (Case 1) and 28 years (Case 2) visited our hospital with lower abdominal pain. Transvaginal ultrasonography showed a 7-cm right ovarian cyst in Case 1 and a 5-cm cyst in the Douglas pouch in Case 2; normal bilateral ovaries and the whirlpool sign were detected in both cases. Under laparoscopic guidance in Cases 1 and 2, an ovarian cyst and a paraovarian cyst were confirmed and removed. Results: Our step-by-step method allowed us to identify the whirlpool sign and confirm adnexal torsion, leading to prompt surgery in both cases. Conclusion: Using a systematic procedure helps less experienced practitioners detect the whirlpool sign.

Educational Effect of Remote Lectures for Students Aiming to Become Radiologic Technologists: Questionnaire on Nuclear Medicine Examinations.

In the latter half of 2019, coronavirus disease 2019 (COVID-19) began spreading worldwide. To prevent COVID-19 infection, all teaching at Suzuka University of Medical Sciences from April to June 2020 took place as remote lectures, not in the face-to-face format. This study analyzed postlecture questionnaire responses regarding face-to-face and remote teaching on the subject of nuclear medicine technology examinations. We examined the educational effect of using remote lectures. Methods: We conducted a questionnaire survey among students by means of a 5-point evaluation scale about satisfaction, comprehension, concentration, preparation, reviewing, and the question environment for face-to-face and remote lectures. Results: We present the results as means and SDs. Satisfaction results for face-to-face and remote lectures were 3.30 ± 0.72 and 3.36 ± 0.88, respectively. Comprehension results for face-to-face and remote lectures were 3.30 ± 0.71 and 3.30 ± 0.83, respectively. Concentration results for face-to-face and remote lectures were 3.50 ± 0.69 and 3.05 ± 0.90, respectively. The preparation results for face-to-face and remote lectures were 2.57 ± 0.88 and 2.67 ± 0.94, respectively. The reviewing results for face-to-face and remote lectures were 2.84 ± 0.85 and 3.39 ± 0.89, respectively. The question environment results for face-to-face and remote lectures lessons were 2.94 ± 0.90 and 3.43 ± 0.84, respectively. There were no significant differences between face-to-face and remote lectures in terms of satisfaction, comprehension, or preparation. There were significant differences between face-to-face and remote lectures in terms of concentration, reviewing, and the questioning environment (P < 0.001). Conclusion: This comparative analysis of the postlecture questionnaire responses for face-to-face and remote formats in nuclear medicine technology examinations showed that remote lectures have a strong educational effect. We believe that, in future, remote lectures should be considered a tool in student education.

Application of a variable filter for presampled modulation transfer function analysis with the edge method.

We devised a new noise filtering method to reduce the noise in the line spread function (LSF) for presampled modulation transfer function (MTF) analysis with the edge method. A filter was designed to reduce noise effectively using a position-dependent filter controlled by the boundary frequency b for low-pass filtering, which is calculated by 1/2d (d: distance from the LSF center). In this filtering process, strong filters with very low b can be applied to regions distant from the LSF center, and the region near the LSF center can be maintained simultaneously by a correspondingly high b. Presampled MTF accuracies derived by use of the proposed method and an edge spread function (ESF)-fitting method were compared by use of simulated ESFs with and without noise, resembling a computed radiography (CR) and an indirect-type flat panel detector (FPD), respectively. In addition, the edge images of clinical CR, indirect-type FPD, and direct-type FPD systems were examined. For a simulated ESF without noise, the calculated MTFs of the variable filtering method agreed precisely with the true MTFs. The excellent noise-reduction ability of the variable filter was demonstrated for all simulated noisy ESFs and those of three clinical systems. Although the ESF-fitting method provided excellent noise reduction only for the CR-like simulated ESF with noise, its noise elimination performance could not be demonstrated due to the lesser robustness of the fitting.

Investigation of measurement accuracy of factors used for detective quantum efficiency measurement in digital radiography.

In the detective quantum efficiency (DQE) evaluation of detectors for digital radiography (DR) systems, physical image quality indices such as modulation transfer function (MTF) and normalized noise power spectrum (NNPS) need to be accurately measured to obtain highly accurate DQE evaluations. However, there is a risk of errors in these measurements. In this study, we focused on error factors that should be considered in measurements using clinical DR systems. We compared the incident photon numbers indicated in IEC 62220-1 with those estimated using a Monte Carlo simulation based on X-ray energy spectra measured employing four DR systems. For NNPS, influences of X-ray intensity non-uniformity, tube voltage and aluminum purity were investigated. The effects of geometric magnifications on MTF accuracy were also examined using a tungsten edge plate at distances of 50, 100 and 150 mm from the detector surface at a source-image receptor distance of 2000 mm. The photon numbers in IEC 62220-1 coincided with our estimates of values, with error rates below 2.5%. Tube voltage errors of approximately ±5 kV caused NNPS errors of within 1.0%. The X-ray intensity non-uniformity caused NNPS errors of up to 2.0% at the anode side. Aluminum purity did not affect the measurement accuracy. The maximum MTF reductions caused by geometric magnifications were 3.67% for 1.0-mm X-ray focus and 1.83% for 0.6-mm X-ray focus.

Examination of the optimal temporal resolution required for computed tomography coronary angiography.

Sub-second multidetector-row computed tomography systems provide great potential for the further improvement of CT coronary angiography (CTCA). However, because the temporal resolution (TR) of such CT systems is insufficient, blurring and artifacts produced by fast cardiac motion remain as unresolved issues. Previous TR investigations of CTCA were based on the retrospective electrocardiogram-gated multisegment reconstruction technique. However, the results obtained may not necessarily be correct because the TR of multisegment reconstruction may not be substantial due to the insufficient periodicity of cardiac motion. The optimal TR required for better CTCA images was evaluated with use of a dual-source CT system, which has various substantial TR modes (83, 125, and 165 ms). CTCA images of 147 patients with heart rates (HRs) ranging from 36 to 117 beats/minute (bpm) were evaluated visually on a 4-point scale. Our results revealed not only that the 165-ms TR is sufficient for low HRs (≤60 bpm), but also that the 83- and 125-ms TRs are unnecessary for such HRs. The image quality with the 125-ms TR mode was acceptable for the left anterior descending artery, left circumflex artery, and right coronary artery at low to intermediate HRs (≤70 bpm). At high HRs (>70 bpm), the 83-ms TR mode resulted in an excellent image quality for all cases except those with very rapid RCA motion. Adequate TRs for a wide range of heart rates (52-106 bpm) are thus clarified.

[Physical image properties of digital radiography systems in low dose range].

We measured physical image properties of a flat panel detector (FPD) system and a computed radiography (CR) system, targeting to a low dose range (reference dose: 2.58×10(-7) C/kg: to 1/20 dose). Input-output properties, pre-sampled modulation transfer functions (pre-sampled MTFs), and normalized noise power spectra for an FPD system equipped with a CsI scintillator (FPDcsi) and a CR system with an imaging plate coated with storage phosphor (CR) were measured at the low dose range for radiation quality of RQA3 (≍50 skV) and RQA5 (≍70 kV), and detective quantum efficiencies (DQEs) were calculated. In addition, in order to validate the DQE results, component fractions of Poisson and multiplicative and additive noise were analyzed using relative standard deviation analysis. The DQE values of FPDcsi were decreased with dose decrease, and contrarily to these, those of CR were increased. At the 1/10 and 1/20 doses for RQA3, the DQEs of FPDcsi and CR became almost the same. From the results of RSD analysis, it was proved that the main cause of DQE deterioration on FPDcsi are non-negligible additive (electronic) noise, and the DQE improvement on CR was caused by both of significant multiplicative (structure) noise and very low electronic noise. The DQE results were validated by comparing burger phantom images of each dose and radiation quality.

[Study of appropriate dosing in consideration of image quality and patient dose on the digital radiography].

Recently about 90% of radiographs have been taken by the digital radiographic system in Japan, but the exposure dose of the patients are about ten-times different among the systems. We understood it by a surveytaken in 2007. We studied the visual evaluation with varying exposure doses using the image phantom of the lumber AP, lumber lateral and hip AP. Additionally we measured quantum efficiency (DQE) of the digital systems. We also studied the exposure index (EI) of IEC standard to see whether it is able to be the sensitivity index among the digital systems. DQE in 1.0 cycle/mm of CR, FPD (GOS), FPD (CsI, a-Se) became 0.2-0.25, 0.3, 0.5, respectively. Our results display that the dose reduction is relative to DQE. The visual evaluation results also show that dose reduction is possible among the systems. From these results, we are able to reduce the exposure dose of the patients at the clinical site. We also suggest that we manage the exposure dose using the E.I of the IEC standard.

[A comparative study of electrocardiogram multi-segment reconstruction and dual source computed tomography using a computer controlled coronary phantom].

Currently, there are two main methods for improving temporal resolution of coronary computed tomography (CT): electrocardiogram-gated multi-segment reconstruction (EMR) and dual source scanning using dual source CT (DSCT). We developed a motion phantom system for image quality assessment of cardiac CT to evaluate these two methods. This phantom system was designed to move an object at arbitrary speeds during a desired phase range in cyclic motion. By using this system, we obtained coronary CT mode images for motion objects like coronary arteries. We investigated the difference in motion artifacts between EMR and the DSCT using a 3-mm-diameter acrylic rod resembling the coronary artery. EMR was evaluated using 16-row multi-slice CT (16MSCT). To evaluate the image quality, we examined the degree of motion artifacts by analyzing the profiles around the rod and the displacement of a peak pixel in the rod image. In the 16MSCT, remarkable increases of artifacts and displacement were caused by the EMR. In contrast, the DSCT presented excellent images with fewer artifacts. The results showed the validity of DSCT to improve true temporal resolution.

[Investigation of error factors in analysis of digital noise power spectrum].

The noise power spectrum (NPS) measurement is important for assessing noise properties of digital radiography systems, and its measurement method was standardized in International Electrotechnical Commission 62220-1 (IEC). However, improvement of its accuracy is not easy due to random data analysis. In this study, regarding error factors in the NPS measurement using 2-dimensional (2D) Fast Fourier transform, we investigated effects of overlap of region of interests (ROIs), number of average lines in 2D frequency space, directional dependence of frequency property, and detrending techniques. If the number of average lines was set so as to obtain a similar frequency range to IEC, total matrix size was the most important factor and error rate was decreased with increasing of the size. For images, including many trends, detrending using 256 x 256-pixels ROI and second-order polynomial fitting was the most effective. Consistent with the previous report, the overlap of ROIs was not effective for improving accuracy. Contrary to the previous report that indicated effectiveness of 128 x 128-pixels ROI for detrending, we demonstrated less affectivity of the ROI size, other than 256 x 256-pixels.

[Influence of angle-measurement error on pre-sampled MTF and proposal of an optimal technique of angle measurement].

The presampled modulation transfer function (MTF) is recognized as the established metric for characterizing the resolution performance of a digital imaging system. In the past, the three general approaches for assessing the presampled MTF were using the angulated slit, angulated edge, and angulated square-wave test pattern all of which are tilted slightly against the column direction of the detector. In all methods, it is important to determine the exact angle of the respective test devices. In this study, we examined the influence of angle-measurement error in three test devices and the optimal technique of angle measurement. These results demonstrated that the influences of angle-measurement error in each method were equal. We also investigated three angle-measurement techniques using trace of objects, Hough transfer, and comparative observation of synthetic profiles. These results suggested that the technique using synthetic profiles was the most optimal technique in the angle measurement. Through use of the technique, angle-measurement error was completely overcome. This technique will contribute to improved accuracy of presampled MTF measurements.

[Proposal and verification of presampled MTF measurement by simple analysis using the edge method].

The edge method adopted by the International Electrotechnical Commission (IEC) for presampled modulation transfer function (presampled MTF) measurement has the advantage that the complexity and limitations of image acquisition are less than those of the slit method. On the other hand, it has the disadvantage that the maintenance of accuracy is difficult because of the noise amplification caused by the differentiation. In order to reduce this disadvantage, we proposed an effective method in which many edge profiles are synthesized and then the synthesized edge profiles are bound into regular interval bins. Furthermore, the influences of some factors in edge profile analysis on measurement accuracy were examined. The appropriate width of one bin was 10-20% of the sampling interval. Measurement error of the inclination angle of the edge should be made up to 0.05 degrees . The range of the angle was allowed to be from 1 to 5 degrees. If these conditions were fulfilled, accurate measurement up to the Nyquist frequency (fn) was possible. Using an actual computed radiography (CR) system, the presampled MTF was obtained by the slit method and our edge method. The two results showed good agreement.