Thyroid Ultrasound and Ultrasound-Guided FNA

---

Releasing the suction before needle withdrawal forces the aspirated specimen into the needle, but not into the needle tract, which could prevent potential complications such as needle tract seeding 1 , 9 , To obtain a sufficient amount of specimen, the operator routinely uses a mL plastic syringe attached to a conventional gauge needle 1 , 7 , 9 , 31 , A syringe holder may or may not be used, according to the preference of the operator.

The number of needle passes, ranging from 2 to 3, for each thyroid nodule is determined depending on the US characteristics of the thyroid nodule and the operator's preference To improve the cellular adequacy of FNA, several methods are recommended. For example, a gentler manipulating needle technique involving small needle size, capillary technique, and short needle dwell time, followed by manual compression would be effective for preventing bloody aspirates and procedure-related hematoma when targeting a hypervascular nodule 1 , 9 , 12 , For cystic or complex lesions, sampling could be done from the solid elements and from suspicious areas of complex lesions after drainage of the viscous colloid using a large needle 1 , 7 , In the parallel technique, the needle advances along the long axis of the probe and is visualized from the skin puncture to the thyroid nodule, allowing the operator to observe needle penetration, location of distal tip, and the entire pathway of the needle 31 , In the perpendicular technique, the nodule is positioned in the mid-portion of the screen and the point of needle insertion might be central, just over the nodule to be targeted 31 , The needle advances perpendicular to the probe footprint at an angle determined by the nodule's depth and only the tip of the needle is visualized when it enters the nodule.

Therefore, the needle tip should be continuously monitored by US to prevent vascular, tracheal or esophageal injury during the entire duration of the FNA. According to one study comparing parallel and perpendicular techniques with regard to specimen adequacy from thyroid nodules, the parallel technique significantly decreased the overall nondiagnostic sampling compared to the perpendicular technique However the sample size of the study was small and the two techniques were applied to different lesions.

Cytologic details of samples will vary depending on the experience of the technical staff or laboratory facilities for handing specimens obtained by US-FNA, thus proper methods should be applied during smearing, fixation, and staining of samples to improve diagnostic yield 1. For conventional smear preparations, the syringe-needle unit is disassembled first. The empty syringe is then filled with air, reconnected to the needle and the needle content is extruded onto glass slides. Sometimes, excessive pressure between the spreader slide and non-spreader slide results in crush artifacts which may interfere with evaluation of nuclear morphology 1 , 4.

Subjects and Methods

Therefore, liquid-based cytology LBC , originally developed for gynecologic cervical smears, was recently introduced for the FNA of thyroid nodules due to its specific advantages including clear background, a monolayer cell preparation, and more convenient handling of specimens 1 , 45 , 46 , This method is based on a two-step procedure: However, several changes that occur during the cellular processing step of LBC, such as loss of cell artitecture, cytomorphologic changes of colloid, and decrease of inflammatory cells, were pointed out as the drawbacks of LBC.

Therefore, a dedicated training program would be necessary for cytopathologists to maintain the diagnsotic accuracy of US-FNA 1 , To summarize the advantages of two different cytologic preparation methods, cellular specimen processing by conventional smear techniques enables rapid, real-time assessment of sample adequacy and allows for a more accurate evaluation of cell architecture and colloids than LBC, whereas LBC enables rapid processing of samples with clearer backgrounds than conventional smears and the possibility of saving material for additional marker studies.

The role of immediate cytologic assessment is controversial 9. Many previous reports have stated that immediate assessment of cytologic adequacy at the time of FNA significantly decreased the numbers of nondiagnostic results and helped to avoid repeated FNAs 10 , 48 , 49 , 50 , However, others did not find a statistically significant difference in cytologic adequacy between FNAs of thyroid nodules with and without immediate cytological analysis, and stated that immediate cytological analysis considerably extended the cost and duration of the procedure It may not be necessary for the success of the procedure to perform an immediate assessment, especially if a highly-experienced operator with a relatively low nondiagnostic rate performs the US-FNA for the thyroid nodule Rather, immediate cytologic assessment can be reserved for the less-experienced operator and for repeat FNA of thyroid nodules with previous nondiagnostic results if available 50 , 51 , Generally, the risk of FNA-related bleeding diminishes with a few minutes of manual compression immediately after needle withdrawal Upon completion of the FNA procedure, the operator should examine the patient's neck to identify any bleeding-related manifestations, such as progressive swelling or ecchymosis.

INTRODUCTION

In addition, it would be empirically recommended for the patient to manually compress the skin puncture site for an additional minute observation period after US-FNA and his or her neck should be ultrasonographically re-examined if FNA-related complications are suspected. This is especially important in patients with bleeding tendencies and these patients should be observed for minutes to detect any bleeding-related symptoms Local pain or bruising can be minimized by an ice pack. The patient should be discharged with instructions to seek medical care if sudden swelling or unrelenting pain occurs In regard to complications related with US-FNA, there is limited epidemiological data on the incidence and the relation to techniques including needle size, number of passes or the technique used.

However, the possibility and severity of complications, including hemorrhage, may be increased by a medical history of hemorrhagic risk factors, thicker needles, vigorous handling of the needle, or lack of operator experience 12 , Local pain and ecchymosis are the most frequent complications related to US-FNA, however, serious events are very rare 4 , 5 , 8 , 25 , Most of the complications related to US-FNA can be sufficiently managed if the physician is aware and the patient is informed 8 , 9. Local pain and slight ecchymosis related to minor hematomas are relatively tolerable; however, if they persist, mild painkillers such as Tylenol or temporary application of an ice pack on the painful area can control the pain very well 9.

Aspirin or aspirin substitutes Motrin, Naprosyn should not be taken within 48 hours after the procedure, although there is no direct evidence against them. Intrathyroidal- or perithyroidal-hemorrhage after US-FNA might be caused by venous extravasation into or around the nodules. Clinical manifestations of hemorrhage include increased pain, swelling and ecchymosis of the neck, dyspnea, dysphonia and dysphagia 9 , If hemorrhage is suspected, the patient's neck should be sonographically examined to ensure stabilization prior to discharging the patient.

Small to moderate-sized hematomas can be successfully managed in out-patient settings with manual compression as well as an ice-pack and they usually resolve spontaneously within days. Only a few cases of uncontrolled hemorrhage, requiring hospital admission and more active intervention, have been reported in the literature 25 , 28 , 29 , Rarely, subendothelial carotid hematoma manifests as acute, persistent pain immediately after US-FNA To prevent bleeding around the thyroid glands or a potential complication such as pseudoaneurysm, firm pressure should be applied after confirming the presence of a hematoma.

Ultrasound-Guided Fine Needle Aspiration Biopsy of the Thyroid

Reduced activity and upper positioning of the head can be useful to decrease the spread of hematoma along the vessel wall. Usually, the hematoma absorbs spontaneously within a week.

Some patients experience vasovagal reactions, such as light-headedness, nausea, sweating, clammy hands or seizure-like activity, due to pain or anxiety about the procedure, prior to, during, or after the procedure 9. Especially, seizure-like activities such as uncontrollable jerking movements of the arms or legs can make the patients feel very scared. The symptoms usually last for minutes. It is advisable to calm the patient by placing them in a supine position with legs slightly elevated and cold compression applied to the forehead 8 , 9.

Vital signs should be immediately monitored. The incidence of needle track seeding following FNA of thyroid carcinomas is exceedingly rare and only a few cases have been reported in the literature Although the evidence is limited, several factors have been presumed to cause needle tract seeding, including larger needle size, excessive or vigorous needle manipulation, withdrawing the needle without releasing suction, and inherent characteristics of the lesion e. In all described cases, surgical treatment successfully removed the tumor seeding, and there was no evidence of recurrence during the follow-up period.

Other rare complications are pseudoaneurysm, recurrent laryngeal nerve palsy, infection or post-FNA thyrotoxicosis 9 , Although US guidance ensures safe and exact targeting, the rates of nondiagnostic FNA results were highly variable and ranged between 0.

What are some common uses of the procedure?

Considering the fact that the results of US-FNA have primarily supported the decision on whether to manage the thyroid nodule medically or surgically, its overall diagnostic yield, which reflects the operator's level of proficiency in this technique, should be continuously monitored 1 , Measuring technical proficiency in US-FNA ideally would include monitoring the frequency of nondiagnostic material leading to missed or delayed diagnoses of cancers.

However, this approach is quite difficult because it requires large numbers of cases and access to long term reliable follow-up in all cases, not just those referred to surgery soon after FNA. For these reasons, the nondiagnostic rate of each operator, documenting the number of nondiagnostic results divided by the number of total FNA procedures, may be used as a limited indicator for the level of proficiency So, nondiagnostic FNA results should not be regarded as simply benign. In general, repeat US-FNA is recommended after a minimum interval of three months to prevent false-positive interpretations caused by reactive or reparative changes 1 , 4 , 6 , In contrast, two recent studies demonstrated that repeat FNAs within a shorter interval did not significantly influence the diagnostic yield of thyroid nodules with previously nondiagnostic results 58 , Therefore, a shorter waiting period may be possible in some patients if malignancy is highly suggested by clinical or US features Alternatively, a core needle biopsy is recommended as a complimentary tool to patients for whom previous FNA results are nondiagnostic to improve the diagnostic yield of US-FNA 60 , Apart from cytologic preparation and interpretation of FNA specimen, the diagnostic yield of US-FNA highly depends on both the US appearance of the thyroid nodule and the operator's experience Table 1 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , For example, certain US features such as cystic dominancy, macrocalcification, size less than mm, or hypoechogenicity, have been reported to increase the likelihood of nondiagnostic sampling despite highly variable nondiagnostic rates between studies 13 , 14 , 15 , 16 , 18 , 19 , 20 , 21 , 23 , 39 , 62 , 63 , Particularly, cystic dominancy and intranodular macrocalcification were reported to be independent findings that increase the possibility of nondiagnostic results, even when experienced operators performed US-FNA US guidance, gauge needle, four passes and preparation of samples four total smears: Especially for a nodule with peripheral calcification, it would be helpful to target the specific portion that favors the possibility of malignancy, such as the area with focal discontinuity or soft tissue rim, rather than an egg-shell like completely calcified rim 32 , 39 , Furthermore, previous studies indicated that approximately 2.

Therefore, FNA sampling should be specifically targeted to the internal solid portion that suggests malignancy after drainage of cystic content. Similar to other operator-dependent procedures, significant differences existed in nondiagnostic rates when US-FNAs were performed by highly experienced versus less experienced groups 13 , 14 , For example, nondiagnostic rates from one comparative study on operator experience were Five patients were lost to follow-up after the procedure and were not included in the analysis.

During the procedure, the patient was kept in the supine position with slight hyperextension of the neck. Local anesthetic was not routinely applied unless requested by the patient. A to gauge needle was introduced next to the medial edge of the transducer, allowing visualization of the tip of the needle while it was guided to the biopsy site. Our initial approach was to perform a first biopsy with partial aspiration of the fluid, followed by a second biopsy of the solid part of the nodule 42 nodules. However, after a high rate of hemorrhage within the cavity of the nodule was observed after partial aspiration, it was decided not to aspirate the fluid and to proceed directly to biopsy the solid part of the nodule.

Once the needle was introduced into the solid part of the nodule, 3—5 ml of negative syringe pressure was applied. After aspiration, the smear was placed on slides and air-dried. One to three slides from each patient were stained with Wright-Giemsa stain to confirm the presence of follicular cells. If follicular cells were scanty or absent, the procedure was repeated until the number of cells was considered sufficient. To evaluate the diagnostic yield from simple aspiration, the fluid from the first 42 samples in which fluid was aspirated was stained with Papanicolaou stain after cytospin cytocentrifugation.

Interpretation of the slides was performed by one of two experienced cytopathologists. A subgroup of 14 patients were referred for surgery, and the surgical pathology was compared with preoperative UG-FNAB. The mean age of the patients was The majority of the nodules were located in the right lobe Eighty-nine percent of the patients were euthyroid at the time of the procedure, and the average longest diameter of the nodules was 2.

There was a problem providing the content you requested

The average number of passes for each nodule was 1. No complications were seen during the procedure. In of the nodules, adequate number of cells were present for cytological diagnosis, yielding a diagnostic rate of Of these nodules, were benign and 2 were malignant.

Results were indeterminate in 7 nodules 6 follicular neoplasm and 1 suspicious for malignancy. Follicular cells were scanty or absent nondiagnostic aspirates in the other 7 nodules.

What is Ultrasound-Guided Fine Needle Aspiration Biopsy of the Thyroid?

Of the initial 42 nodules in which fluid aspiration was performed, 11 On UG-FNAB, 23 were confirmed to be benign colloid nodules, 1 was nondiagnostic, and 2 were diagnosed as indeterminate follicular lesion one of these patients was referred for surgery, and the surgical pathology showed colloid goiter. Numbers in parentheses represent the number of patients.

All patients with either a benign or a malignant diagnosis on UG-FNAB had confirmation of these cytological findings on surgical pathology. One patient with nondiagnostic cytology was found to have papillary carcinoma. Among four patients with indeterminate results follicular neoplasm on cytology, one had a benign colloid nodule, one had a follicular adenoma, one had a papillary carcinoma, and one had a follicular carcinoma.

Accuracy for the detection of malignancy was These data clearly suggest that complex nodules are better evaluated under ultrasound guidance. The transducer is a small hand-held device that resembles a microphone, attached to the scanner by a cord. Some exams may use different transducers with different capabilities during a single exam. The transducer sends out high-frequency sound waves that the human ear cannot hear into the body and then listens for the returning echoes from the tissues in the body. The principles are similar to sonar used by boats and submarines.

The ultrasound image is immediately visible on a video display screen that looks like a computer or television monitor. The image is created based on the amplitude loudness , frequency pitch and time it takes for the ultrasound signal to return from the area within the patient that is being examined to the transducer the device placed on the patient's skin to send and receive the returning sound waves , as well as the type of body structure and composition of body tissue through which the sound travels.

A small amount of gel is put on the skin to allow the sound waves to travel from the transducer to the examined area within the body and then back again. Ultrasound is an excellent modality for some areas of the body while other areas, especially air-filled lungs, are poorly suited for ultrasound.

Ultrasound-Guided Fine Needle Aspiration Biopsy of the Thyroid

The physician inserts a fine gauge needle through the skin and advances it into the thyroid nodule. Samples of the cells are then obtained and put on a slide for review by the pathologist. Image-guided, minimally invasive procedures such as fine needle aspiration of the thyroid are most often performed by a specially trained radiologist with experience in needle aspiration and ultrasound.

The neck will be cleansed with antiseptic. Medicine to numb the area may or may not be used. An ultrasound transducer with a small amount of sterile water soluble gel will be placed on your neck over the thyroid nodule. The radiologist will insert the needle through the skin under direct imaging guidance, advance it to the site of the thyroid nodule and aspirate samples of tissue. After the sampling, the needle will be removed. New needles will be reinserted if additional samples are required. Several specimens may be needed for a complete analysis.

Once the biopsy is complete, pressure will be applied to the area to decrease the risk of bleeding. A bandage may be placed if necessary. No sutures are needed.

During the test, you will lie on your back with a pillow under your shoulders, your head tipped backward, and your neck extended. This position makes it easier for the radiologist to access the thyroid gland. You may feel some pressure on your neck from the ultrasound transducer and mild discomfort as the needle is moved to obtain the cells. You will be asked to remain still and not to cough, talk, swallow or make a sound during the procedure. Aftercare instructions vary, but generally you can resume normal activities and any bandage can be removed within a few hours.

The biopsy site may be sore and tender for one to two days.

• Penning Poesies
• Logics Prophet: An Original Screenplay
• LAISSEZ MOI VOUS ATTENDRE (French Edition)
• Seduzione milionaria (Italian Edition)
• Iphigenie in Aulis - Versuch einer Darstellung aus rezeptionsgeschichtlicher Sicht (German Edition)