PurposeWe estimated the volume of vestibular schwannomas by an ice cream cone formula using thin-sliced magnetic resonance images (MRI) and compared the estimation accuracy among different estimating formulas and between different models.MethodsThe study was approved by a local institutional review board. A total of 100 patients with vestibular schwannomas examined by MRI between January 2011 and November 2015 were enrolled retrospectively. Informed consent was waived. Volumes of vestibular schwannomas were estimated by cuboidal, ellipsoidal, and spherical formulas based on a one-component model, and cuboidal, ellipsoidal, Linskey’s, and ice cream cone formulas based on a two-component model. The estimated volumes were compared to the volumes measured by planimetry. Intraobserver reproducibility and interobserver agreement was tested. Estimation error, including absolute percentage error (APE) and percentage error (PE), was calculated. Statistical analysis included intraclass correlation coefficient (ICC), linear regression analysis, one-way analysis of variance, and paired t-tests with P < 0.05 considered statistically significant.ResultsOverall tumor size was 4.80 ± 6.8 mL (mean ±standard deviation). All ICCs were no less than 0.992, suggestive of high intraobserver reproducibility and high interobserver agreement. Cuboidal formulas significantly overestimated the tumor volume by a factor of 1.9 to 2.4 (P ≤ 0.001). The one-component ellipsoidal and spherical formulas overestimated the tumor volume with an APE of 20.3% and 29.2%, respectively. The two-component ice cream cone method, and ellipsoidal and Linskey’s formulas significantly reduced the APE to 11.0%, 10.1%, and 12.5%, respectively (all P < 0.001).ConclusionThe ice cream cone method and other two-component formulas including the ellipsoidal and Linskey’s formulas allow for estimation of vestibular schwannoma volume more accurately than all one-component formulas.

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Patient: Female, 41-year-old Final Diagnosis: Incidental pregnancy Symptoms: Postprandial abdominal pain and fullness for months Clinical Procedure: — Specialty: Gastroenterology and Hepatology • Obstetrics and Gynecology • Radiology Objective: Mistake in diagnosis Background: Ionizing radiation poses potential health risk to fetuses, including growth retardation, organ malformations, neurological effects, fetal death, and cancer. Therefore, pregnant women rarely undergo X-ray imaging, unless absolutely necessary. However, they can be inadvertently exposed to X-rays while undergoing an examination without being aware of their pregnancy. Given that the likelihood of a fetus appearing on an abdominal radiograph is low, physicians can be unfamiliar with the appearance of a fetus on such images. If a fetus incidentally appears on an abdominal radiograph, the clinician can encounter difficulties in identifying the fetus, potentially leading to unexpected harm during subsequent imaging procedures. Case Report: A 41-year-old woman presented with symptoms of postprandial abdominal pain, abdominal fullness, and urinary frequency. Abdominal radiography revealed a large mass with calcifications in the pelvis and lower abdomen, raising suspicion of a large pelvic tumor, such as a teratoma. However, subsequent ultrasound unexpectedly revealed that the woman was actually 6 months pregnant. The presumed tumor was an enlarged uterus, and the presumed calcifications were the fetus’s bones. Before X-ray, the woman had denied being pregnant, mistakenly attributing her condition to excess weight and irregular menstrual cycles. Fortunately, the use of ultrasound instead of computed tomography prevented radiation exposure to the fetus, and the baby was delivered in a healthy state at full term. Conclusions: To avoid unintended harm to fetuses, clinicians should consider the possibility of pregnancy when evaluating a pelvic mass in women of childbearing age. To aid clinicians in accurately identifying fetuses on abdominal radiography and thereby reduce the likelihood of misdiagnosis, we propose the “circled delta sign” and the “reversed circled delta sign”.