From the Department of Surgery, Baylor University Medical Center, Dallas, Texas.

Corresponding author: Brian M. Gogel, MD, Department of Surgery, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, Texas 75246.

Ultrasound examination is painless, requires no radiation exposure, and is easily performed after proper training. The real-time nature of ultrasound allows for accurate image-guided biopsies or aspirations. Ultrasound has become routine in the practice of cardiologists, urologists, gastroenterologists, and gynecologists. More recently, surgeons have used ultrasound for blunt abdominal trauma, intraoperative guidance, and breast disease.

Introducing ultrasound into surgical office practice has been facilitated by refinements in computer-enhanced ultrasonographic imaging and more affordable ultrasound units. When ultrasound is performed as a part of the surgeon's physical examination, the management of thyroid disease is streamlined. This prospective study seeks to examine how surgical office-based thyroid ultrasound impacts the diagnosis and management of thyroid disease.

METHODS

From December 1997 to August 1998, surgical office-based thyroid ultrasound was performed on 49 consecutive patients who presented with thyroid disease. Data were collected prospectively to examine the lesional analysis of ultrasound and its impact on treatment management. The patient group included 42 women and 7 men, with a median age of 54 (range, 17 to 88 years). All patients were examined with a Seimens Sonoline ultrasound system (Koeln, Germany) with a 7.5-MHz probe. Ultrasound technique was standardized to include transverse and longitudinal images of both lobes of the thyroid gland as well as the adjacent structures in the neck. All nodules were measured in 3 planes, and hard copy images were created to document nodule location and orientation. Thyroid nodules were characterized by number, location, and echogenicity.

FNA biopsy, when indicated, was performed under ultrasound guidance to ensure accurate sampling. Biopsy was performed with a 25-gauge needle and a 5-mL disposable syringe under local anesthesia. Sterile gel was used as the coupling agent, and the needle was inserted along a path within the scanning plane so that the nodule and the needle were continuously visualized. When the needle reached the target, aspiration biopsy was performed with an in-and-out movement while suction was applied. Suction was released before the needle was removed from the nodule. The collected material was expelled onto glass slides, fixed immediately by a trained cytotechnologist, and placed into a cytolyte solution for centrifugation and examination of a pellet. Samples were interpreted by a cytopathologist as benign, follicular, malignant, or inadequate.

The 2-tailed paired Student's t test was used to evaluate the statistical significance of the data; calculations were performed using StatView software (SAS Institute, Cary, NC).

RESULTS

There were 5 different indications for surgical referral in the patient group: solitary palpable nodule (66%), hormonal abnormalities (14%), diffuse thyroid enlargement (10%), multiple thyroid nodules (6%), or radiologic evidence of tracheal compression (4%). Physical examination identified 14 patients with solitary thyroid nodules, 18 patients with vaguely palpable lesions, and 3 patients with multiple thyroid nodules. Diffuse thyroid enlargement was noted in 5 patients, and no masses were identified in 9 patients. Of the 49 patients in this study, ultrasound identified a multinodular process in 20 patients and a solitary nodule in 20 patients. Five patients were noted to have cystic lesions.

Ultrasound examination of the thyroid gland identified more nodules than physical examination (104 vs 38, P < 0.0001). In the subpopulation of patients who had thyroid scintigraphy performed (n = 10), ultrasound also identified more nodules than scintigraphy (24 vs 10, P < 0.01).

FNA biopsy was performed on 27 patients; ultrasound guidance was used to ensure proper needle placement. Cytological analysis revealed follicular cells (n = 9), malignant or suspicious cells (n = 5), benign cells (n = 10), or nondiagnostic cells (n = 3).

Overall, surgical office-based thyroid ultrasound impacted the clinical management of 40 patients (80%). In 16 of these patients, thyroid ultrasound was the only modality that demonstrated a multinodular condition, thus contributing to a decision to avoid surgery. Five patients underwent ultrasound-guided cyst aspiration and follow-up. Ultrasound facilitated FNA biopsy of vaguely palpable or nonpalpable lesions in 19 patients. Thyroid exploration was avoided in 10 patients on the basis of benign FNA cytology obtained via ultrasound guidance.

Indications for thyroid resection included malignant or suspicious cytology (n = 14), toxic nodule (n = 3), indeterminate cytology (n = 1), and mass effect of an enlarged thyroid (n = 1). Thyroid resection was performed on 19 patients (12 lobectomies and 7 total thyroidectomies). Pathologic analysis revealed a malignancy in 7 (37%) resected thyroid glands (Table).

DISCUSSION

Ultrasound is an excellent complement to the surgeon's physical examination and facilitates determination of nodule size, number, and echogenicity. Ultrasound can be used to evaluate potential cervical lymphadenopathy, recurrent laryngeal nerve invasion, and adjacent neck structures. In our experience, ultrasound identifies significantly more thyroid lesions than either physical examination or scintigraphy.

Ultrasound has emerged as the preferred modality for imaging the thyroid. The excellent resolution of ultrasound and accessibility of the thyroid gland enable the identification of foci as small as 3 mm (5). The development of biopsy guide devices for ultrasound transducers has also facilitated improved accuracy and reduced sampling error. With the combination of an experienced aspirator and cytopathologist, the accuracy of cytologic diagnosis of thyroid lesions approaches 95% (6). Recent technological advancements have expanded the usefulness of ultrasound by allowing physicians to accurately obtain tissue in the office.

The evaluation, treatment, and follow-up of multinodular vs single-nodule disease of the thyroid are significantly different. Early differentiation of the 2 processes allows for more efficient management. In this study, ultrasound proved to be the most accurate modality for differentiating a solitary thyroid nodule from a multinodular process. In 16 patients, ultrasound was the only modality that demonstrated multinodularity. FNA of a dominant nodule in the setting of a multinodular thyroid can provide further evidence of a benign process, since 5% to 10% of patients with multinodular disease may have thyroid carcinoma. Ultrasound can also be used in the surveillance of multinodular or cystic disease of the thyroid. Patients can then be selected for surgery if an existing nodule changes size or echostructure (7).

Patients with solitary nodules identified by ultrasound are appropriate candidates for FNA analysis. Obtaining an accurate FNA is often difficult in patients with unfavorable cervical anatomy or with small lesions. In our experience, ultrasound facilitated FNA of vaguely palpable or nonpalpable thyroid nodules in 19 patients. Accurate biopsy of these lesions would have been impossible without ultrasound guidance. Numerous reports indicate that the introduction of thyroid FNA increases the yield of carcinoma from 14% to as much as 30% at the time of thyroidectomy (8). In our review, 37% of thyroid resections yielded a diagnosis of carcinoma. Pathological differentiation of follicular lesions requires careful sectioning of the entire lesion to identify vascular or capsular invasion to diagnose malignancy. By considering the follicular adenomas with the malignancies, the yield is improved to 78.9%. Improved patient selection with surgical office-based thyroid ultrasound reduces exposure to operative morbidity, such as recurrent laryngeal nerve and parathyroid injury.

Incorporation of ultrasound into the surgeon's diagnostic armamentarium leads to streamlined evaluation of thyroid disease. A surgeon who can examine, image, diagnose, and treat a thyroid mass improves continuity of care and reduces the time and expense required for evaluation.

1. Fujimoto Y, Oka A, Omoto R, Hirose M. Ultrasound scanning of the thyroid gland as a new diagnostic approach. Ultrasonics 1967;5:177-180.
2. Rizzatto G, Solbiati L, Croce F, Derchi LE. Aspiration biopsy of superficial lesions: ultrasonic guidance with a linear-array probe. AJR Am J Roentgenol 1987;148:623-625.
3. Hatada T, Okada K, Ishii H, Ichii S, Utsunomiya J. Evaluation of ultrasound-guided fine-needle aspiration biopsy for thyroid nodules. Am J Surg 1998;175:133-136.
4. Brander A, Viikinkoski P, Tuuhea J, Voutilainen L, Kivisaari L. Clinical versus ultrasound examination of the thyroid gland in common clinical practice. J Clin Ultrasound 1992;20:37-42.
5. Scheible W, Leopold GR, Woo VL, Gosink BB. High-resolution real-time ultrasonography of thyroid nodules. Radiology 1979;133:413-417.
6. Liu Q, Castelli M, Gattuso P, Prinz RA. Simultaneous fine-needle aspiration and core-needle biopsy of thyroid nodules. Am Surg 1995;61:628-632.
7. Cohen M, Lubin E, Olsha M, Freeman JL, Feinmesser R. Treatment decisions in thyroid surgery based upon ultrasonography. Isr J Med Sci 1996;32:1302-1305.
8. Gharib H, Goellner JR, Johnson DA. Fine-needle aspiration cytology of the thyroid. A 12-year experience with 11,000 biopsies. Clin Lab Med 1993;13:699-709.