Preoperative detection of pancreatic insulinomas on multiphasic helical CT

OBJECTIVE

The objective was to analyze enhancement characteristics of insulinomas and to determine the ability of multiphase CT to localize these tumors.

MATERIALS AND METHODS

Prospective interpretations of multiphase helical CT scans were reviewed in 30 patients who had insulinomas resected over a 5-year period. CT scans were retrospectively reviewed to determine enhancement characteristics, tumor conspicuity in each phase of enhancement, and potential causes for false-negative findings.

RESULTS

Sixty-three percent (19/30) of tumors were identified on CT prospectively. An additional six tumors were visualized in retrospect, allowing characterization of 25 (83%) of 30 tumors. Most tumors were hyperdense on at least one phase (n = 19), three tumors were hypoattenuating, and three were isodense and pedunculated. Insulinomas were most conspicuous on the early phase in 15 patients and in the portal venous phase in three. All tumors that underwent pancreatic phase imaging were seen (13/13), whereas three of 18 arterial and six of 25 portal venous phase findings were inconclusive for tumor. In the six examinations with false-negative findings in which the tumor could be seen in retrospect, two tumors were isodense and pedunculated, three were in close proximity to vessels, and one had a cystic appearance.

CONCLUSION

Multiphasic CT has a moderate sensitivity in the detection of insulinomas. Most tumors are more conspicuous on the earlier phases of enhancement. The pancreatic phase may be more useful than the arterial phase. Potential sources of false-negative results include tumors adjacent to vessels, pedunculated morphology, or nonhyperattenuating lesions.

Imaging-guided radiofrequency ablation of solid renal tumors

OBJECTIVE

We performed a retrospective review of imaging-guided radiofrequency ablation of solid renal tumors.

MATERIALS AND METHODS

Since May 2000, 35 tumors in 20 patients have been treated with radiofrequency ablation. The size range of treated tumors was 0.9-3.6 cm (mean, 1.7 cm). Reasons for patient referrals were a prior partial or total nephrectomy (nine patients), a comorbidity excluding nephrectomy or partial nephrectomy (10 patients), or a treatment alterative to nephron-sparing surgery (one patient who refused surgery). Tumors were classified as exophytic, intraparenchymal, or central. Sixteen patients had 31 lesions that showed serial growth on CT or MR imaging. Of these 16 patients, four patients with 10 lesions had a history of renal cell carcinoma, and two patients with 11 lesions had a history of von Hippel-Lindau disease. Four patients had incidental solid masses, two of which were biopsied and shown to represent renal cell carcinoma, and the remaining two masses were presumed malignant on the basis of imaging features. Successful ablation was regarded as any lesion showing less than 10 H of contrast enhancement on CT or no qualitative evidence of enhancement after IV gadolinium contrast-enhanced MR imaging.

RESULTS

Of the 35 tumors, 22 were exophytic and 13 were intraparenchymal. Twenty-seven of the 35 were treated percutaneously using either sonography (n = 22) or CT (n = 5). Two patients had eight tumors treated intraoperatively using sonography. Patients were followed up with contrast-enhanced CT (n = 18), MR imaging (n = 5), or both (n = 5) with a follow-up range of 1-23 months (mean, 9 months). No residual or recurrent tumor and no major side effects were seen.

CONCLUSION

Preliminary results with radiofrequency ablation of exophytic and intraparenchymal renal tumors are promising. Radiofrequency ablation is not associated with significant side effects. Further follow-up is necessary to determine the long-term efficacy of radiofrequency ablation.

Painful metastases involving bone: feasibility of percutaneous CT- and US-guided radio-frequency ablation

PURPOSE

To determine the safety and efficacy of radio-frequency (RF) ablation for pain reduction, quality of life improvement, and analgesics use reduction in patients with skeletal metastases.

MATERIALS AND METHODS

Over 10 months, 12 adult patients with a single painful osteolytic metastasis in whom radiation therapy or chemotherapy had failed and who reported severe pain (pain score > or = 4 [scale of 0-10]) over a 24-hour period were treated with percutaneous imaging-guided RF ablation with a multi-tined electrode while under general anesthesia. Patient pain was measured with a Brief Pain Inventory 1 day after the procedure, every week for 1 month, and thereafter every other week (total follow-up, 6 months). Patient analgesics use was also recorded at these follow-up intervals. Follow-up contrast material-enhanced computed tomography was performed 1 week after the procedure. Complications were monitored. Analysis of the primary end point was undertaken with paired comparison procedures.

RESULTS

Lesion size was 1-11 cm. Before RF ablation, mean worst pain score in a 24-hour period in 12 patients was 8.0 (range, 6-10). At 4 weeks after treatment, mean worst pain decreased to 3.1 (P =.001). Mean pain before treatment was 6.5 and decreased to 1.8 (P <.001) 4 weeks after treatment. Mean pain interference in general activity decreased from 6.6 to 2.7 (P =.002) 4 weeks after treatment. Eight of 10 patients using analgesics reported reduced use at some time after RF ablation. No serious complications were observed.

CONCLUSION

RF ablation of painful osteolytic metastases is safe, and the relief of pain is substantial.

Ultrasound-guided biopsy and ablation in the neck

Management and therapy of conditions of the thyroid, parathyroid glands, and cervical lymph nodes have evolved rapidly during the past 15 years. The development and continued improvement of high-resolution ultrasound (US) equipment, US-guided biopsy, and image-guided ablative techniques have fueled this change. These technical improvements and the knowledge and experience gained during this time have decreased the rate of unnecessary surgery in patients with thyroid nodules. They have also allowed more limited neck dissection in patients with parathyroid adenomas and have led to the development of US-guided ablative techniques that have eliminated the need for surgery in some cases. This article reviews the rationale and techniques of US-guided biopsy of the thyroid, parathyroid, and cervical lymph nodes. Established and evolving ablative techniques of these structures are also examined.

Percutaneous ethanol injection for treatment of cervical lymph node metastases in patients with papillary thyroid carcinoma

OBJECTIVE

The objective of this study was to evaluate the technique, efficacy, and side effects of percutaneous ethanol injection in patients with limited cervical nodal metastases from papillary thyroid carcinoma.

SUBJECTS AND METHODS

Fourteen patients who had undergone thyroidectomy for papillary thyroid carcinoma presented with limited nodal metastases (one to five involved nodes) in the neck between May 1993 and April 2000. All patients had received previous iodine-131 ablative therapy with a mean total dose per patient of 7,548 MBq. Ten of the patients either were considered poor surgical candidates or preferred not to have surgery, and all were unresponsive to iodine-131 therapy. Each metastatic lymph node was treated with percutaneous ethanol injection, and patients received both clinical and sonographic follow-up.

RESULTS

Twenty-nine metastatic lymph nodes in our 14 patients were injected. Mean sonographic follow-up was 18 months (range, from 2 months to 6 years 5 months). All treated lymph nodes decreased in volume from a mean of 492 mm(3) before percutaneous ethanol injection to a mean volume of 76 mm(3) at 1 year and 20 mm(3) at 2 years after treatment. Six nodes were re-treated 2-12 months after initial percutaneous ethanol injection because of persistent flow on color Doppler sonography (n = 4), stable size (n = 1), or increased size (n = 1). Two patients developed four new metastatic nodes during the follow-up period that were amenable to percutaneous ethanol injection. Two patients developed innumerable metastatic nodes that precluded retreatment with percutaneous ethanol injection. No major complications occurred. All patients experienced long-term local control of metastatic lymph nodes treated by percutaneous ethanol injection. In 12 of 14 patients, percutaneous ethanol injection was successful in controlling all known metastatic adenopathy.

CONCLUSION

Sonographically guided percutaneous ethanol injection is a valuable treatment option for patients with limited cervical nodal metastases from papillary thyroid cancer who are not amenable to further surgical or radioiodine therapy.

Ultrasound-guided intervention: expanding horizons

Ultrasound-guided intervention has enjoyed a period of unprecedented growth because its many advantages over other guidance modalities have been recognized. The decreased procedure time, increased accuracy, and safety of procedures performed under ultrasound guidance are of obvious benefit to radiologist and patient alike for all interventional applications. Lesions once considered unsafe to sample are now reasonably approached with ultrasound guidance. As equipment technology continues to improve and radiologists increasingly recognize the benefits of guiding procedures with ultrasound, the shift of procedures away from CT and fluoroscopic guidance will continue and ultrasound guidance will become the guidance method of choice for most interventional procedures.

Penetrating injury to the brainstem after a nailgun accident: a case study

Nonfatal penetrating injuries to the brainstem offer a unique opportunity to assess subcortical auditory pathway function. A case study of a patient suffering a severe nailgun accident is presented. Hearing sensitivity and acoustic reflexes were normal bilaterally, but word recognition was reduced for one ear. Auditory brainstem response results indicated waves I-IV were present bilaterally, but wave V was absent bilaterally. Results of vestibular findings indicated central pathology also. Results of audiologic, vestibular, radiologic, neurologic, and physical medicine examinations are discussed.

Electronic imaging and clinical implementation: work group approach at Mayo Clinic, Rochester

Electronic imaging clinical implementation strategies and principles need to be developed as we move toward replacement of film-based radiology practices. During an 8-month period (1998 to 1999), an Electronic Imaging Clinical Implementation Work Group (EICIWG) was formed from sections of our department: Informatics Lab, Finance Committee, Management Section, Regional Practice Group, as well as several organ and image modality sections of the Department of Diagnostic Radiology. This group was formed to study and implement policies and strategies regarding implementation of electronic imaging into our practice. The following clinical practice issues were identified as key focus areas: (1) optimal electronic worklist organization; (2) how and when to link images with reports; (3) how to redistribute technical and professional relative value units (RVU); (4) how to facilitate future practice changes within our department regarding physical location and work redistribution; and (5) how to integrate off-campus imaging into on-campus workflow. The EICIWG divided their efforts into two phases. Phase I consisted of Fact finding and review of current practice patterns and current economic models, as well as radiology consulting needs. Phase II involved the development of recommendations, policies, and strategies for reengineering the radiology department to maintain current practice goals and use electronic imaging to improve practice patterns. The EICIWG concluded that electronic images should only be released with a formal report, except in emergent situations. Electronic worklists should support and maintain the physical presence of radiologists in critical areas and direct imaging to targeted subspecialists when possible. Case tools should be developed and used in radiology and hospital information systems (RIS/HIS) to monitor a number of parameters, including professional and technical RVU data. As communication standards improve, proper staffing models must be developed to facilitate electronic on-campus and off-campus consultation.

Indications, technique, and efficacy of alcohol injection of enlarged parathyroid glands in patients with primary hyperparathyroidism

BACKGROUND

Percutaneous alcohol ablation of the parathyroid gland (PAAP) has been proposed as an alternative treatment for primary hyperparathyroidism in patients unsuitable for surgery. The current study aimed to determine the (1) selection criteria, (2) associated morbidity, and (3) efficacy of PAAP.

METHODS

From 1987 to 1998, 36 patients with primary hyperparathyroidism (mean age 65 years) underwent PAAP. The indications for PAAP were (1) medical comorbidity, (2) technically unsafe reoperative surgery, (3) partial ablation of a single remaining gland, and (4) patient choice.

RESULTS

There were no long-term complications. Two patients had temporary recurrent laryngeal nerve injury and 4 had temporary hypocalcemia. Over a median follow-up of 16 months, 12 (33%) of the patients remained eucalcemic. For analysis purposes patients were separated into 2 separate groups: 29 with attempted complete ablation and 7 with partial ablation of a single remaining gland only. Ten of the complete ablation group (34%) remained eucalcemic. In the partial ablation group only 2 remained eucalcemic, but all had adequately controlled serum calcium levels.

CONCLUSION

PAAP should be considered for hyperparathyroid patients with excessive reoperative morbidity or prohibitive medical comorbidity or those in whom the intent is to partially ablate a single remaining enlarged gland. In these patients close follow-up of serum calcium is required, and repeat treatments may be necessary because recurrence of hypercalcemia is likely.

Phase I study of immunotherapy of hepatic metastases of colorectal carcinoma by direct gene transfer of an allogeneic histocompatibility antigen, HLA-B7

We have completed a phase I study to test feasibility and toxicity of immunotherapy of hepatic metastases from colorectal carcinoma by direct gene transfer of HLA-B7, a MHC class I gene. Eligible patients were HLA-B7 negative, immunocompetent by PHA lymphocyte stimulation and had at least two measurable hepatic lesions on CT scan for measurement of response of the injected lesion, as well as evaluation of possible distant response. Under ultrasonographic guidance the hepatic lesions were injected with Allovectin-7, a liposomal vector containing the combination of the HLA-B7 gene with beta 2-microglobulin formulated with the lipid DMRIE-DOPE. Eligible patients were injected on two schedules. On the first schedule patients received an injection on day 1 and the injected lesion was biopsied to determine transfection every 2 weeks for 8 weeks. Doses were escalated from 10 micrograms to 50 micrograms to 250 micrograms with three patients treated at each level. The second schedule included multiple injections of 10 micrograms. Three patients received injections on days 1 and 15. Three patients received injections on days 1, 15 and 29. A total of 15 patients have completed treatment. The plasmid DNA was detected in 14 of 15 patients (93%) by PCR. In five of 15 patients (33%) mRNA was also detected. The HLA-B7 protein was detected in five of eight patients (63%) by immunohistochemistry and in seven of 14 patients (50%) tested by fluorescence activated cell sorting (FACS) analysis. There has been no serious toxicity directly attributable to allovectin-7. Our results suggest that liposomal gene transfer by direct injection is feasible and non-toxic. Further studies will be necessary in order to establish the therapeutic efficacy.

The role of ultrasonography and automatic-needle biopsy in outpatient percutaneous liver biopsy

The risk of complications from percutaneous liver biopsy is low, but discomfort is common and complications require hospitalization in approximately 4% of patients. The optimal method of performing these biopsies is unknown. The goal of our study was to determine whether the use of ultrasonography in the biopsy room immediately prior to or during the procedure would lessen the risk of complications and to compare the safety and efficacy in obtaining tissue by use of a Trucut needle versus an automatic biopsy needle. Between 1992 and 1994, 836 patients were entered into a randomized study (489 in Rochester, MN; 347 in Barcelona, Spain). Patients were randomized immediately prior to liver biopsy into four groups: Trucut needle, or automatic biopsy needle, and with or without ultrasonography. Fisher's Exact Test and a logistic regression model were also used to assess the effect of needle and ultrasonography on the odds for complications. The four biopsy groups were well-matched at entry with respect to age, sex, underlying liver disease, hemoglobin, prothrombin time, and platelet count. The use of ultrasound was associated with a decreased rate of hospitalization for pain, hypotension, or bleeding (2 vs. 9, P < .05). No difference in safety was found between the two types of needles. The number of passes needed to obtain specimens was similar for all four groups. The average length of the specimen was slightly greater with ultrasonographic-guided biopsies (1.7 mm vs. 1.6 mm, P < .05) and with biopsies obtained using the automatic biopsy needle when compared with the Trucut needle (1.7 mm vs. 1.5 mm, P < .05), but this did not seem to be clinically important. The addition of ultrasonography reduces complications in patients undergoing percutaneous liver biopsy. The type of needle appears to offer little difference in safety or yield of diagnostic tissue. The use of ultrasonography for guidance of percutaneous liver biopsy will lead to a lower rate of complications. The value of this benefit must be weighed against the added cost of ultrasonographic guidance.

The role of ultrasonography and automatic-needle biopsy in outpatient percutaneous liver biopsy

The risk of complications from percutaneous liver biopsy is low, but discomfort is common and complications require hospitalization in approximately 4% of patients. The optimal method of performing these biopsies is unknown. The goal of our study was to determine whether the use of ultrasonography in the biopsy room immediately prior to or during the procedure would lessen the risk of complications and to compare the safety and efficacy in obtaining tissue by use of a Trucut needle versus an automatic biopsy needle. Between 1992 and 1994, 836 patients were entered into a randomized study (489 in Rochester, MN; 347 in Barcelona, Spain). Patients were randomized immediately prior to liver biopsy into four groups: Trucut needle, or automatic biopsy needle, and with or without ultrasonography. Fisher's Exact Test and a logistic regression model were also used to assess the effect of needle and ultrasonography on the odds for complications. The four biopsy groups were well-matched at entry with respect to age, sex, underlying liver disease, hemoglobin, prothrombin time, and platelet count. The use of ultrasound was associated with a decreased rate of hospitalization for pain, hypotension, or bleeding (2 vs. 9, P < .05). No difference in safety was found between the two types of needles. The number of passes needed to obtain specimens was similar for all four groups. The average length of the specimen was slightly greater with ultrasonographic-guided biopsies (1.7 mm vs. 1.6 mm, P < .05) and with biopsies obtained using the automatic biopsy needle when compared with the Trucut needle (1.7 mm vs. 1.5 mm, P < .05), but this did not seem to be clinically important. The addition of ultrasonography reduces complications in patients undergoing percutaneous liver biopsy. The type of needle appears to offer little difference in safety or yield of diagnostic tissue. The use of ultrasonography for guidance of percutaneous liver biopsy will lead to a lower rate of complications. The value of this benefit must be weighed against the added cost of ultrasonographic guidance.

Solitary thyroid nodule. Comparison between palpation and ultrasonography

OBJECTIVE

To determine the accuracy of clinical palpation in the diagnosis of solitary thyroid nodule in comparison with ultrasonographic findings.

METHODS

From a computerized database of 1774 patients with the diagnosis of nodular thyroid disease made from January 1990 through December 1991 at our institution, we retrieved and reviewed the medical records of the 193 patients who underwent ultrasonography of the thyroid (42 patients with multinodular glands on palpation were excluded). Nodules were categorized as "solitary" or "dominant nodule of a multinodular gland." Concordance rates were measured between results of palpation and ultrasonographic findings.

RESULTS

Of 151 patients included in the study, 78 had solitary nodules on ultrasonography and 73 had multiple nodules. Of those with multiple nodules, 49 had two nodules and 24 had three or more nodules. Of clinically palpable nodules, 89% were 1 cm or greater in diameter. In 72% of the patients with multiple nodules, the other nodules not identified on palpation were less than 1 cm in diameter. The overall concordance rate between the size of the solitary nodule or the dominant nodule in a multinodular gland estimated with clinical palpation and the actual size seen on ultrasonography was 72%. The relationship between multiple nodules and malignancy was not statistically significant.

CONCLUSIONS

Our results suggest that (1) a palpable solitary nodule represents a multinodular gland in about 50% of patients, (2) clinical palpation is less sensitive than thyroid ultrasonography in identifying multiple nodules, and (3) palpation is reliable only if a nodule is at least 1 cm in diameter. We recommend that small, occult (impalpable) thyroid nodules not be considered clinically important; they do not warrant further evaluation unless ultrasonographic features suggest malignancy or the nodule increases in size.

Thyroid and parathyroid imaging

This article reviews the current roles of imaging in the diagnosis of thyroid and parathyroid disorders, with an emphasis on ultrasound evaluation. Imaging of the thyroid and parathyroid can be performed with nuclear medicine, ultrasound, CT, and MRI. Indications for thyroid and parathyroid imaging studies have recently changed. The availability of experienced endocrine surgeons, as well as the development of accurate laboratory tests, fine-needle aspiration (FNA) biopsy, and high-resolution ultrasound, have dramatically influenced the evaluation of thyroid and parathyroid disease. In patients with thyroid nodular disease, a clinical examination by an experienced clinician with appropriate lab values and palpation-guided FNA is the current diagnostic protocol of choice. Ultrasound evaluation of high-risk patients and ultrasound-guided FNA both augment this protocol when necessary. In patients with diffuse thyroid glandular disease, radionuclide imaging and color Doppler sonography both can be used for evaluation. When preoperative imaging is clinically necessary, sonography or scintigraphy can be used for parathyroid adenoma localization in patients with primary hyperparathyroidism. The recent development of technetium-99m sestamibi as a parathyroid imaging agent has improved the sensitivity of scintigraphy for parathyroid adenoma localization. Ultrasound and radionuclide imaging have also become valuable imaging techniques for parathyroid localization in patients with recurrent or persistent hyperparathyroidism.

Imaging of gastrointestinal neuroendocrine tumors

Gastrointestinal neuroendocrine tumors are rare neoplasms that cause classic clinical syndromes because of the excess secretion of specific gastrointestinal hormones. The two most important tumors clinically are insulinomas and gastrinomas. The clinical management of patients with these disorders usually involves the localization and surgical removal of the responsible tumor. Many radiological techniques can be used for tumor localization, including preoperative and intraoperative ultrasound, endoscopic ultrasound, CT, MRI, radionuclide scanning, angiography, and venous sampling. However, there are conflicting claims as to the relative accuracy of these procedures, and many of these investigations are difficult to justify because of their high cost, degree of invasiveness, or lack of precise anatomic information that is obtained. If surgical resection of a neuroendocrine tumor is planned, intraoperative sonography should always be used to detect occult nonpalpable tumors and to discern the relationship of the tumor to vital adjacent pancreatic ductal anatomy. The choice of preoperative imaging is more controversial, and depends on the clinical problem, local expertise, and availability of imaging techniques. Sonography and contrast-enhanced helical CT are the most commonly used preoperative imaging methods, because of their relatively low cost and widespread availability. Radionuclide scanning with a somatostatin analogue, which is a relatively new procedure, may be valuable in patients with symptoms of tumor recurrence.

Purified CD34+ Lin- Thy+ stem cells do not contain clonal myeloma cells

High-dose therapy with autologous marrow or peripheral blood stem cell (PBSC) rescue has been extensively applied in the treatment of multiple myeloma (MM) patients during the past 10 years resulting in improved event-free and overall survival when compared with standard chemotherapy. However, relapses are common and cure is unlikely in the majority of patients. Because both bone marrow and PBSCs are contaminated with myeloma cells it is conceivable that relapse after autotransplantation originates at least in part from autografted tumor cells. In this study, mobilized PBSCs were examined for the presence of myeloma cells based on immunophenotyping and sensitive polymerase chain reaction (PCR)-based techniques. In addition, CD34+ Lin- Thy+ stem cells were purified from mobilized PBSC harvests of 10 MM patients by sequentially using counterflow elutriation centrifugation, treatment with phenylalanine methylester, and flow sorting, using 5-parameter gating (propidium iodide, forward scatter, side scatter, CD34+ v Lin- and CD34+ v Thy+). Virtually all mobilized unsorted PBSC preparations contained myeloma cells in sufficient quantities (range, < 0.01 to > 10%) potentially causing a disease relapse. Stem cell purification led to an overall enrichment by about 50-fold in all 10 patients; approximately 90% of the final cell population expressed CD34+ Lin- Thy+ with no evidence of myeloma cell contamination based on flow cytometric analysis of CD38bright cells (< 0.1%). Quantitative PCR amplification of patient-specific complementarity determining region III (CDRIII) DNA sequences showed depletion of clonal B cells by 2.7 to 7.3 logs, with the highest log reduction noted in the samples initially containing the most tumor cells. Our results show that purification of CD34+ Lin- Thy+ cells depletes myeloma cells to undetectable levels from up to 10% present in unsorted PBSCs, thus offering a tool to investigate whether MM relapse after autotransplantation can be reduced markedly.

MR measurements of mesenteric venous flow: prospective evaluation in healthy volunteers and patients with suspected chronic mesenteric ischemia

PURPOSE

To quantify portal vein (PV) and superior mesenteric vein (SMV) flow before and after a standardized meal in healthy volunteers and to prospectively evaluate patients with a clinical suspicion of chronic mesenteric ischemia on the basis of magnetic resonance (MR) measurement of flow in the mesenteric venous system in volunteers.

MATERIALS AND METHODS

Cine phase-contrast flow measurements were acquired in 10 asymptomatic volunteers and in 10 patients.

RESULTS

In volunteers, the difference between the fasting and post-prandial flows in the SMV and PV was significant (P < .001), with a peak flow augmentation of 245% +/- 74 and 70% +/- 29, respectively. Postprandial augmentation of peak flow in the SMV was significantly less in patients with mesenteric ischemia compared with volunteers (64% +/- 28; P = .02). SMV flow augmentation in patients without mesenteric ischemia did not differ significantly from that in volunteers (206% +/- 36; P = .31).

CONCLUSION

Measurement of postprandial flow augmentation in the SMV with MR imaging shows promise as a noninvasive screening test for chronic mesenteric ischemia.

Sonography guides biopsy and therapy in the neck

Sonography is a powerful imaging method that can be used in the evaluation of patients with thyroid and parathyroid disease. The role of sonography in visualizing normal superficial neck structures and detecting small pathologic neck masses is being enhanced and expanded by its ability to accurately characterize suspected pathologic processes through precise percutaneous needle biopsy under real-time visualization.

Thyroid imaging techniques

Nuclear medicine, ultrasound, CT, and MRI are imaging methods that can be used to evaluate the thyroid gland. All these techniques give structural information about the thyroid gland and show the location and size of thyroid nodules. Nuclear medicine scanning also adds functional information about nodules. In many practices, however, FNA has supplanted imaging methods as the primary method of thyroid nodule evaluation because it is safe, inexpensive, and results in a better selection of patients for operation. Imaging studies are very useful in the setting of recurrent thyroid cancer. Ultrasound is extremely sensitive in the detection of recurrent malignancy in regional cervical lymph nodes and as a guide in performing a biopsy of these nodes. CT is very useful in identifying distant metastases in the chest and abdomen. Nuclear medicine scanning can detect functioning distant metastases when the metastases are from differentiated thyroid cancers. MRI can be used to evaluate the possibility of recurrent thyroid cancer; however, because of its relatively high cost, it is used less frequently than other imaging methods.