Diagnostic ultrasound ( PDFDrive )

CHAPTER 19 The Thyroid Gland 715
A
B
FIG. 19.31 Use of Ultrasound Elastography on Thyroid Nodule: Benign Nodular Hyperplasia (Pattern 1). (A) Conventional longitudinal
B-mode sonogram with color Doppler shows a hypoechoic solid nodule (arrows) with peripheral halo, internal comet-tail artifacts, and perilesional
blood low pattern. (B) Longitudinal ultrasound elastography at same location demonstrates a “soft” color pattern.
FIG. 19.32 Use of Ultrasound Elastography on Thyroid Nodule: Benign Nodular Hyperplasia With Cystic Changes (Pattern 2). Left half
of image shows a cystic, poorly deined nodule on conventional B-mode gray-scale sonogram. Right half of elastogram of the nodule shows a
predominantly elastic (green) pattern with a few internal anelastic bandlike areas.
pressure is required and pulsations of the carotid artery induce
the displacement necessary to assess tissue elasticity. 89 Several
papers and recent meta-analyses show very interesting results
of qualitative and quantitative elastography. 90-93
Four elastographic patterns have been classiied as
follows 86,87,94,95 :
Pattern 1: Elasticity in the whole nodule (Fig. 19.31)
Pattern 2: Elasticity in a large part of the nodule, with inconstant
appearance of anelastic areas (Fig. 19.32)
Pattern 3: Constant presence of large unelastic areas at the
periphery (Fig. 19.33)
Pattern 4: Uniformly unelastic (Fig. 19.34)
In literature reports, 78% to 100% of benign nodules had a
score of 1 to 2, whereas 88% to 96% of malignant nodules had
a score of 3 to 4. Sensitivity was 82% to 97%, speciicity 78% to
100%, positive predictive value 64% to 81%, and negative predictive
value 91% to 98%. 87-98 Speciicity and sensitivity are relatively
independent of the nodule size. However, the best accuracy is
achieved in small nodules and when FNA biopsy is nondiagnostic
or suggests a follicular lesion, provided the nodule is solid and
devoid of coarse calciications. Both strain elastography and SWE
should be performed as additional tools to conventional ultrasound
and to guide follow-up of lesions previously diagnosed
as benign at FNA because multiparametric sonographic assessment
can increase the accuracy of the ultrasound evaluation (Fig.
19.35), avoiding unnecessary biopsies or surgery.
Guidance for Needle Biopsy
Sonographically guided percutaneous needle biopsy of cervical
masses has become an important technique in many clinical
situations. Its main advantage is that it afords continuous realtime
visualization of the needle, a crucial requirement for the
biopsy of small lesions. Most physicians use a 25-gauge needle,
employing either capillary action or minimal suction with a