Takahiro Hosokawa

Dose reduction in chest CT: Comparison of the adaptive iterative dose reduction 3D, adaptive iterative dose reduction, and filtered back projection reconstruction techniques

OBJECTIVES To assess the effectiveness of adaptive iterative dose reduction (AIDR) and AIDR 3D in improving the image quality in low-dose chest CT (LDCT). MATERIALS AND METHODS Fifty patients underwent standard-dose chest CT (SDCT) and LDCT simultaneously, performed under automatic exposure control with noise index of 19 and 38 (for a 2-mm slice thickness), respectively. The SDCT images were reconstructed with filtered back projection (SDCT-FBP images), and the LDCT images with FBP, AIDR and AIDR 3D (LDCT-FBP, LDCT-AIDR and LDCT-AIDR 3D images, respectively). On all the 200 lung and 200 mediastinal image series, objective image noise and signal-to-noise ratio (SNR) were measured in several regions, and two blinded radiologists independently assessed the subjective image quality. Wilcoxons signed rank sum test with Bonferronis correction was used for the statistical analyses. RESULTS The mean dose reduction in LDCT was 64.2% as compared with the dose in SDCT. LDCT-AIDR 3D images showed significantly reduced objective noise and significantly increased SNR in all regions as compared to the SDCT-FBP, LDCT-FBP and LDCT-AIDR images (all, P ≤ 0.003). In all assessments of the image quality, LDCT-AIDR 3D images were superior to LDCT-AIDR and LDCT-FBP images. The overall diagnostic acceptability of both the lung and mediastinal LDCT-AIDR 3D images was comparable to that of the lung and mediastinal SDCT-FBP images. CONCLUSIONS AIDR 3D is superior to AIDR. Intra-individual comparisons between SDCT and LDCT suggest that AIDR 3D allows a 64.2% reduction of the radiation dose as compared to SDCT, by substantially reducing the objective image noise and increasing the SNR, while maintaining the overall diagnostic acceptability.

Abdominal CT: an intra-individual comparison between virtual monochromatic spectral and polychromatic 120-kVp images obtained during the same examination

OBJECTIVES To compare quantitative and subjective image quality between virtual monochromatic spectral (VMS) and conventional polychromatic 120-kVp imaging performed during the same abdominal computed tomography (CT) examination. MATERIALS AND METHODS Our institutional review board approved this prospective study; each participant provided written informed consent. 51 patients underwent sequential fast kVp-switching dual-energy (80/140 kVp, volume CT dose index: 12.7 mGy) and single-energy (120-kVp, 12.7 mGy) abdominal enhanced CT over an 8 cm scan length with a random acquisition order and a 4.3-s interval. VMS images with filtered back projection (VMS-FBP) and adaptive statistical iterative reconstruction (so-called hybrid IR) (VMS-ASIR) (at 70 keV), as well as 120-kVp images with FBP (120-kVp-FBP) and ASIR (120-kVp-ASIR), were generated from dual-energy and single-energy CT data, respectively. The objective image noises, signal-to-noise ratios and contrast-to-noise ratios of the liver, kidney, pancreas, spleen, portal vein and aorta, and the lesion-to-liver and lesion-to-kidney contrast-to-noise ratios were measured. Two radiologists independently and blindly assessed the subjective image quality. The results were analyzed using the paired t-test, Wilcoxon signed rank sum test and mixed-effects model with Bonferroni correction. RESULTS VMS-ASIR images were superior to 120-kVp-FBP, 120-kVp-ASIR and VMS-FBP images for all the quantitative assessments and the subjective overall image quality (all P<0.001), while VMS-FBP images were superior to 120-kVp-FBP and 120-kVp-ASIR images (all P<0.004). CONCLUSIONS VMS images at 70 keV have a higher image quality than 120-kVp images, regardless of the application of hybrid IR. Hybrid IR can further improve the image quality of VMS imaging.

Changes in the Distance Between the Distal Rectal Pouch and Perineum From the Birth Day to the Next Day in Neonates With an Imperforate Anus

To evaluate changes in the distance between the distal rectal pouch and the perineum (pouch‐perineum distance) from the birth day to the next day and to determine which day is better for diagnosis of a low‐type imperforate anus in neonates.

Five neonatal cases of pyriform sinus fistula with cervical cystic lesion: a comparison between sonography and other modalities

Pyriform sinus fistulas are an unusual cause of neck cystic lesions in neonates. A definitive diagnosis requires detection of the fistula, which originates from the pyriform sinus and extends to the cystic lesion. Sonography has been reported to be useful for detecting fistulas. However, there have been no reports of neonatal cases in which sonography could detect fistulas not detected by other modalities, such as barium esophagography, computed tomography (CT), or magnetic resonance imaging (MRI). We describe five neonatal patients with pyriform sinus fistula-appearing cervical cystic lesions. All patients were examined by sonography; of these, three patients were also examined by barium esophagography, two by CT, and one by MRI. The fistula was detected by sonography but not CT in one patient and by barium esophagography but not MRI in one. Two patients whose fistulas were detected by sonography had an oval-shaped and relatively small cystic lesion. One patient whose fistula could be detected only by barium esophagography had a relatively large cystic lesion. In two patients, whose fistulas were not detected by sonography or barium esophagography, sonography revealed air bubbles within the cystic lesions, and a pyriform sinus fistula was suspected. Without requiring ionizing radiation, sonography was thus useful in diagnosing pyriform sinus fistula-appearing cervical cystic lesions in neonatal cases. On the other hand, in two patients whose fistulas were not detected by sonography, the shape of the cystic lesion was polygonal or multicystic. In two of three patients with infectious signs, a fistula could not be detected. The shape and size of the cystic lesion and the presence of infectious signs may be important factors for detecting fistulas.

Malignant transformation of a mature cystic teratoma of the ovary with rupture

Malignant transformation or tumor rupture is a rare complication of ovarian mature cystic teratomas. We present computed tomography (CT) images of a 52-year-old woman that revealed a large, predominantly cystic mass filled with fat and enhanced solid components located in the lower abdomen. Ten days later, the cystic mass ruptured, and massive ascites was observed on magnetic resonance imaging (MRI). Resulting from the rupture, MRI revealed reduced size and thickening wall of the tumor. After resection, the mass ruptured, and malignant transformation (squamous cell carcinoma) was observed. To our knowledge, there are no reports describing before and after images of a ruptured cystic teratoma with malignant transformation.

Role of Sonography for Evaluation of Gastrointestinal Foreign Bodies.

Foreign body ingestion is frequently encountered in children. The locations of the foreign bodies and the period during which they have been present in the thorax and abdomen are important for determining the method and timing of treatment. Although plain radiography and computed tomography are primarily used for assessment of foreign bodies, sonography without radiation is also useful for diagnosis of foreign bodies. This report describes 5 cases of foreign bodies in the digestive tract and the usefulness of sonography for real‐time evaluation of foreign bodies with high spatial resolution. Physicians can use sonography along with radiography and computed tomography in cases involving foreign bodies.

Comparison of Diagnostic Accuracy for the Low-Type Imperforate Anus Between Prone Cross-Table Radiography and Sonography

To compare the diagnostic accuracy for the low‐type imperforate anus between prone cross‐table radiography and sonography.

Distance Between the Distal Rectal Pouch and Perineum in Neonates of Low-Birth Weight With Imperforate Anus

Abstract This study was to evaluate the correlation between birth weight and the distance between distal rectal pouch and perineum (P-P distance) and to determine a cutoff value for P-P distance to diagnose low-type imperforate anus in neonates with low-birth weight (LBW). We included 15 neonates with LBW (mean weight, 2012 ± 470 g; range, 906–2452 g) and imperforate anus (surgically confirmed: 11 low type and 3/1 intermediate/high type), who underwent ultrasonography on the day after birth. Type of imperforate anus was defined based on the International Classification of Anorectal Anomalies. The P-P distances on ultrasonograms were measured. Pearson correlation coefficient test and receiver operating characteristic curve were used for statistical analyses. Among all 15 neonates, nonsignificant correlation was observed between the birth weight and P-P distance (r = 0.36; P = 0.18). Mean P-P distance was 9.0 ± 6.6 mm (range, 1.0–24.0 mm) in all neonates, 5.7 ± 2.8 mm (range, 1.0–11.0 mm) in the 11 neonates with low-type imperforate anus, and 18.3 ± 9.1 mm (range, 14.0–24.0 mm) in the 4 neonates with intermediate-/high-type imperforate anus. Using cutoff P-P distance of 12.5 mm, sensitivity and specificity for diagnosis of low-type imperforate anus were 100% (11/11) and 100% (4/4), respectively. In conclusion, nonsignificant correlation was observed between P-P distance and birth weight, and cutoff P-P distance to diagnose low-type imperforate anus was 12.5 mm. Despite the very small sample size in our study, and only 4 neonates with intermediate-/high-type imperforate anus, these findings are important because surgical management whether transperineal anoplasty or diverting colostomy is decided based on the type of imperforate anus, and P-P distance to diagnose the type of imperforate anus was feasible even in neonates with LBW.

Diagnostic Accuracy of Sonography for Detection of a Fistula on the Birth Day in Neonates With an Imperforate Anus: Comparison of Diagnostic Performance Between Suprapubic and Perineal Approaches

To evaluate the diagnostic accuracy of sonography for detection of an internal fistula on the birth day in neonates with an imperforate anus and to compare the diagnostic performance between the suprapubic and perineal approaches.

Sonography for an Imperforate Anus: Approach, Timing of the Examination, and Evaluation of the Type of Imperforate Anus and Associated Anomalies

This systematic review outlines the role of sonography in an imperforate anus. The diagnostic performance for type of imperforate anus is superior on the day after birth than that on the day of birth by using the pouch‐perineum distance. Three approaches can be used (suprapubic, infracoccygeal, and perineal). The pouch‐perineum distance, fistula location, and relationship between the puborectalis muscle and distal rectal pouch are useful for classifying the type of imperforate anus. However, the pouch‐perineum distance measured has an overlap between the low and high/intermediate types of imperforate anus. Sonography can be useful for some of the associated anomalies and helpful for surgeons in some cases.