Aki Kido

MR features of physiologic and benign conditions of the ovary.

In reproductive women, various physiologic conditions can cause morphologic changes of the ovary, resembling pathologic conditions. Benign ovarian diseases can also simulate malignancies. Magnetic resonance imaging (MRI) can play an important role in establishing accurate diagnosis. Functional cysts should not be confused with cystic neoplasms. Corpus luteum cysts typically have a thick wall and are occasionally hemorrhagic. Multicystic lesions that may mimic cystic neoplasms include hyperreactio luteinalis, ovarian hyperstimulation syndrome, and polycystic ovary syndrome. Recognition of clinical settings can help establish diagnosis. In endometrial cysts, MRI usually provides specific diagnosis; however, decidual change during pregnancy should not be confused with secondary neoplasm. Peritoneal inclusion cysts can be distinguished from cystic neoplasms by recognition of their characteristic configurations. Ovarian torsion and massive ovarian edema may mimic solid malignant tumors. Recognition of normal follicles and anatomic structures is useful in diagnosing these conditions. In pelvic inflammatory diseases, transfascial spread of the lesion should not be confused with invasive malignant tumors. Radiologic identification of abscess formation can be a diagnostic clue. Many benign tumors, including teratoma, Brenner tumor, and sex-cord stromal tumor, frequently show characteristic MRI features. Knowledge of MRI features of these conditions is essential in establishing accurate diagnosis and determining appropriate treatment.

Diffusion tensor imaging of kidneys with respiratory triggering: Optimization of parameters to demonstrate anisotropic structures on fraction anisotropy maps

To demonstrate the feasibility of diffusion tensor imaging (DTI) of kidneys with respiratory triggering, and determine the optimal imaging parameters for fraction anisotropy (FA) maps.

MRCP imaging at 3.0 T vs. 1.5 T: preliminary experience in healthy volunteers.

To evaluate the impact of magnetic resonance cholangiopancreatography (MRCP) imaging at 1.5T and 3.0T on image quality.

Retained products of conception masquerading as acquired arteriovenous malformation.

This case documents a seldom-described event of retained products of conception masquerading as an acquired arteriovenous malformation (AVM) of the uterus. The patient presented with sudden onset of heavy vaginal bleeding 6 weeks after artificial abortion. Ultrasonography and magnetic resonance imaging revealed a diffuse intramural lesion predominantly consisting of prominent vessels, which raised suspicion of an AVM. Hysterectomy revealed retained products of placenta that were necrotic and encroached into thin myometrium.

MRI of the female pelvis at 3T compared to 1.5T: Evaluation on high‐resolution T2‐weighted and HASTE images

To evaluate the feasibility of MRI of the female pelvis using high‐resolution T2‐weighted imaging (T2WI) and the half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) technique at 3 Tesla (T) compared to 1.5T, while focusing on the uterine body and cervical anatomy.

Oral Contraceptives and Uterine Peristalsis: Evaluation with MRI

To evaluate the effects of oral contraceptives (OCs) on uterine contractility using cine MRI, and correlate the kinematic findings with the static findings.

Incidence and characteristics of uterine leiomyomas with FDG uptake

ObjectiveUterine leiomyomas sometimes show focal 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) images that may result in a false-positive diagnosis for malignant lesions. This study was conducted to investigate the incidence and characteristics of uterine leiomyomas that showed FDG uptake.MethodsWe reviewed FDG-PET and pelvic magnetic resonance (MR) images of 477 pre-menopausal (pre-MP, age 42.1 ± 7.3 years) and 880 post-MP (age 59.9 ± 6.8 years) healthy women who underwent these tests as parts of cancer screening. Of 1357, 323 underwent annual cancer screening four times, 97 did three times, 191 did twice, and the rest were screened once. Focal FDG uptake (maximal standardized uptake value > 3.0) in the pelvis was localized and characterized on co-registered PET/MR images.ResultsUterine leiomyomas were found in 164 pre-MP and 338 post-MP women. FDG uptake was observed in 18 leiomyomas of 17 of the 164 (10.4%) pre-MP women and in 4 leiomyomas of 4 of the 338 (1.2%) post-MP women. The incidence was significantly higher in pre-MP women than in post-MP women (chi-square, P < 0.001). Of the 22, 13 showed signal intensity equal to or higher than that of the myometrium on T2-weighted MR images, which suggested abundant cellularity, whereas the majority of leiomyomas without FDG uptake showed low signal intensity. Of the 13 women, 12 examined more than twice showed substantial changes in the level of FDG uptake in leiomyomas each year with FDG uptake disappearing or newly appearing. These changes were observed frequently in relation with menopause or menstrual phases.ConclusionsLeiomyomas with focal FDG uptake were seen in both pre-and post-MP women with a higher incidence in pre-MP women. Abundant cellularity and hormonal dependency may explain a part of the mechanisms of FDG uptake in leiomyomas. It is important to know that the level of FDG uptake in leiomyomas can change and newly appearing FDG uptake does not necessarily mean malignant transformation.

Uterine peristalsis: comparison of transvaginal ultrasound and two different sequences of cine MR imaging.

To compare uterine peristalsis as seen on two different magnetic resonance (MR) imaging sequences and transvaginal ultrasound (TVUS), so as to better determine the best method for evaluating uterine peristalsis.

Diffusion tensor MRI of the kidney at 3.0 and 1.5 Tesla

Background: Diffusion tensor imaging (DTI) at 3 T provides information on the microstructure and pathophysiology of tissues that is not available from conventional imaging with an advantage of high signal to noise ratio (SNR). Purpose: To evaluate the feasibility of DTI of the normal kidney at 3.0 T compared to results obtained at 1.5 T. Material and Methods: DTI of the normal kidney of 15 healthy volunteers obtained with 3.0 and 1.5 T scanners using respiration-triggered acquisition was examined. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of both the renal cortex and the medulla and SNRs were measured (b-values 0 and 400 s/mm2, diffusion direction of 6). The image quality of FA and ADC maps was also compared subjectively. Results: The FA values of the renal cortex were 0.15 ± 0.03 at 3.0 T and 0.14± 0.03 at 1.5 T on average. This difference was not significant. The FA values of the renal medulla were 0.49 ±0.04 at 3.0 T and 0.42 ± 0.05 at 1.5 T. ADC values of the renal cortex were 2.46 × 10−3± 0.09 mm2/s at 3.0 T and 2.20 ×10−3±0.11 mm2/s at 1.5 T. The ADC values of the renal medulla were 2.08 × 10−3 ± 0.08 mm2/s at 3.0 T and 1.90 × 10−3± 0.11 mm2/s at 1.5 T. These FA and ADC values were consistent with previous publications. The difference was significant for the FA value of the medulla (P< 0.01) and ADC values in both cortex and medulla (P < 0.01). The subjective image quality of the FA map with the 3.0 T scanner was significantly superior to that with the 1.5 T scanner (P< 0.01), but not significant for the ADC map (P = 0.18). There was a significant difference in SNR between 3.0 T (48.8 ± 6.6) and 1.5 T images (32.8 ± 5.0). Conclusion: The feasibility of renal DTI with a 3.0 T magnet resulting in improved SNR was demonstrated.

MR imaging of the female pelvis at 3 Tesla: Evaluation of image homogeneity using different dielectric pads

To evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads.