Preoperative assessment of myometrial invasion of endometrial cancer by MR imaging and intrauterine ultrasonography with a high-frequency probe: preliminary study

Fabrication and evaluation of a single-element Bi0.5Na0.5TiO3-based ultrasonic transducer

This paper discusses the fabrication and characterization of a single-element ultrasonic transducer with a lead-free piezoelectric active element. A piezoelectric ceramic with composition of 0.88Bi(0.5)Na(0.5)TiO(3)-0.08Bi(0.5)K(0.5)TiO(3)- 0.04Bi(0.5)Li(0.5)TiO(3) was chosen as the active element of the transducer. This composition exhibited a thickness coupling coefficient (kt) of 0.45, a dielectric constant of 440 (at 1 kHz), and a longitudinal piezoelectric coefficient (d(33)) of 84 pC·N(-1). To make the transducer, the ceramic was sandwiched between an epoxy-tungsten backing layer and a silver epoxy matching layer. An epoxy lens was also incorporated into the transducer's design to focus the ultrasound beam. The focused transducer with a center frequency of about 23 MHz demonstrated a -6-dB bandwidth of 55% and an insertion loss of -32 dB; the -20-dB pulsed length was measured to be 150 ns. A phantom made of copper wires (30 μm in diameter) was utilized to investigate the imaging capability of the transducer. The results indicated that the fabricated transducer, with a lateral resolution of 260 μm and a relatively high depolarization temperature, could be considered as a candidate for replacement of lead-based ultrasonic transducers.

MR imaging in endometrial carcinoma as a diagnostic tool for the absence of myometrial invasion

OBJECTIVE

To evaluate whether magnetic resonance imaging (MRI) is a reliable modality for verifying preoperative diagnosis of stage IA endometrial carcinoma.

METHODS

One hundred sixteen patients with endometrial carcinoma underwent preoperative pelvic non-contrast T2-weighted or dynamic MRI. We compared the interpretations of the MRI results with the histological findings of the resected uterus.

RESULTS

In assessing the depth of myometrial invasion, the accuracy of MRI was 62.1%. As to the presence of cancerous myometrial invasion, the positive predictive value was 94.4% as high as previously reported by other institutions. However, the negative predictive value, the probability of the absence of myometrial invasion, was only 42.2%. Even when dynamic study was applied to the patient, the value only improved up to 60.0%.

CONCLUSION

MRI has a definite advantage in evaluating deep myometrial invasion, but not the absence of invasion. We should take precautions against the risk of under-diagnosis when selecting stage IA endometrial carcinoma with use of MRI to preserve fertility or to eliminate lymphadenectomy.

Accuracy of frozen section for the operative management of endometrial cancer

OBJECTIVE

To assess the accuracy of intra-operative frozen section reports at identifying the features of high risk uterine disease compared with final histopathology.

DESIGN

Retrospective study.

METHODS

The records of 460 patients with uterine cancer registered with the Queensland Centre for Gynaecological Cancer between January 1, 1996 and December 31, 1998 were reviewed. Intra-operative frozen section was undertaken in 260 patients with endometrial adenocarcinoma. Frozen section pathology was compared with the final histopathology reports. Inter-observer reliability was assessed using percentage agreement and kappa statistics. Clinical notes were also reviewed to determine if errors resulted in sub-optimal patient care.

RESULTS

Respectively, tumour grade and depth of myometrial invasion were accurately reported in 88.6% of cases (expected 61.5%, Kappa 0.70) and 94.7% (expected 53.8%, Kappa 0.89). Errors were predominantly attributable to difficulties with respect to the interpretation of tumour grade. The error resulted in the patient receiving sub-optimal surgical management in only 11 cases (5.3%)

CONCLUSION

Frozen section is accurate at identifying the features of high risk uterine disease in the setting of endometrial cancer and can play an important role in directing primary operative management.