Ultrasound-guided regional anesthesia: learning with an optimized cadaver model

Ultrasound-guided injection into the lateral crico-arytenoid muscle: a pilot study

OBJECTIVES

The anterior, percutaneous Botulinum neurotoxin (BoNT) injection in the lateral cricoarytenoid muscle (LCA) guided by laryngeal electromyography (LEMG) is considered the golden standard treatment for several neurolaryngological disorders. The study presented in this article aims to assess the effectiveness of an alternative approach by which the injection is performed laterally under ultrasound monitoring.

STUDY DESIGN

Anatomical dissection study in human cadavers.

SETTINGS

Academic health care center.

METHODS

Ultrasound-guided bilateral dye (0.1 mL of dye solution containing cold-curing polymers, latex, acrylates, acrylic esters, alcohol, and green color) injection in the LCA was performed by means of 24G needles and 1 mL syringes using the lateral approach. The dye location and distribution were assessed by anatomic dissection, performed immediately after the injection.

RESULTS

In 9/10 specimens, the dye was exclusively detectable in the LCA. In 1/10 case (left side), the dye could not be delivered in the LCA because of unintended penetration of the thyroid cartilage by the needle during injection. Anatomic dissection confirmed that the dye spread neither into the thyroarytenoid (TA) nor the cricothyroid muscle (CT).

CONCLUSIONS

The anatomic dissection following lateral dye injection in the LCA under ultrasound guide confirmed the precision of this approach in delivery a substance exclusively in a pre-determined target. This feature makes this method an interesting addition or alternative to the standard LEMG-guided BoNT injection at least when the LCA is its target.

LEVEL OF EVIDENCE

III.

European Society of Anaesthesiology and Intensive Care Guidelines on peri-operative use of ultrasound for regional anaesthesia (PERSEUS regional anesthesia): Peripheral nerves blocks and neuraxial anaesthesia

Nowadays, ultrasound-guidance is commonly used in regional anaesthesia (USGRA) and to locate the spinal anatomy in neuraxial analgesia. The aim of this second guideline on the PERi-operative uSE of UltraSound (PERSEUS-RA) is to provide evidence as to which areas of regional anaesthesia the use of ultrasound guidance should be considered a gold standard or beneficial to the patient. The PERSEUS Taskforce members were asked to define relevant outcomes and rank the relative importance of outcomes following the GRADE process. Whenever the literature was not able to provide enough evidence, we decided to use the RAND method with a modified Delphi process. Whenever compared with alternative techniques, the use of USGRA is considered well tolerated and effective for some nerve blocks but there are certain areas, such as truncal blocks, where a lack of robust data precludes useful comparison. The new frontiers for further research are represented by the application of USG during epidural analgesia or spinal anaesthesia as, in these cases, the evidence for the value of the use of ultrasound is limited to the preprocedure identification of the anatomy, providing the operator with a better idea of the depth and angle of the epidural or spinal space. USGRA can be considered an essential part of the curriculum of the anaesthesiologist with a defined training and certification path. Our recommendations will require considerable changes to some training programmes, and it will be necessary for these to be phased in before compliance becomes mandatory.

Ultrasound-Guided Neuraxial Anesthesia

PURPOSE OF REVIEW

There has been a recent surge of interest in clinical applications of ultrasound, which has revolutionized acute pain management. This review is to summarize the current status of ultrasound utilization in neuraxial anesthesia, the most common type of regional anesthesia.

RECENT FINDINGS

Ultrasound-assisted and ultrasound-guided neuraxial anesthesia has improved clinical accuracy and patient safety through landmark identification including proper vertebral level and midline, as well as via measurements on neuraxial space. Direct needle or catheter visualization during the entire procedure has not yet been achieved consistently. The recent introduction of ultrasound into neural anesthesia has clinical performance benefits and patient safety implications, with documented improvement on overall efficacy with higher first attempt success rate as well as less needle pass. More controlled studies are needed for the overall impact of ultrasonography in neuraxial anesthesia in obstetric and non-obstetric patients.

Anesthesia of the anterior femoral cutaneous nerves for total knee arthroplasty incision: randomized volunteer trial

BACKGROUND AND OBJECTIVES

For pain relief after total knee arthroplasty (TKA), an injection at the midthigh level may produce analgesia inferior to that of a femoral nerve block as the anterior femoral cutaneous nerves (intermediate femoral cutaneous nerve (IFCN) and medial femoral cutaneous nerve (MFCN)) are not anesthetized. The IFCN can be selectively anesthetized in the subcutaneous tissue above the sartorius muscle and the MFCN by an injection in the proximal part of the femoral triangle (FT). The primary aim was to investigate the area of cutaneous anesthesia in relation to the surgical incision for TKA and anteromedial knee area after intermediate femoral cutaneous nerve blockade (IFCNB) in combination with an injection in the proximal or distal part of the FT (proximal vs distal femoral triangle block (FTB)).

METHODS

The study was carried out as two separate investigations: first, dissection of nine cadaver sides to verify a technique for IFCNB; second, a volunteer study with 40 healthy volunteers. The surgical midline incision for TKA was drawn bilaterally. All volunteers received an active distal FTB combined with a placebo proximal FTB on one side and vice versa on the other side. All volunteers were randomized to an active IFCNB on one side and placebo IFCNB on the contralateral side.

RESULTS

Identification of IFCN was successful in all cadaver sides. Fifteen out of 20 volunteers had complete anesthesia of the incision line after IFCNB combined with proximal FTB, which was significantly higher compared with proximal FTB alone and with distal FTB+IFCNB. A gap at the anteromedial knee area was present in 2/20 volunteers with proximal FTB compared with 17/20 with distal FTB when all volunteers had active IFCNB.

CONCLUSION

Ultrasound-guided blockade of the IFCN and MFCN anesthetize the surgical midline incision and the anteromedial area of the knee relevant for TKA. In contrast, an injection at the midthigh level produces insufficient cutaneous anesthesia not covering the areas of interest.

TRIAL REGISTRATION NUMBER

EudraCT: 2018-004986-15.

The inguinal region revisited: the surgical point of view : An anatomical-surgical mapping and sonographic approach regarding postoperative chronic groin pain following open hernia repair

PURPOSE

Inguinodynia or chronic post-herniorrhaphy pain, defined as pain lasting longer than 3 months after open inguinal hernia repair, has become the most important complication after inguinal surgery and therefore compromises the patient´s quality of life. A major reason for inguinodynia might be the lack of neuroanatomical knowledge and suboptimal "management" of the nerves during surgery.

METHODS

We present a detailed neuroanatomic mapping of the inguinal region by dissection including the most important surgical landmarks with all nerves confirmed by immunohistochemistry, ultrasound guided visualization of the iliohypogastric, ilio-inguinal, and genital branch of the genitofemoral nerve, and a practical (preoperative) algorithm for clinical management.

RESULTS

Surgically and ultrasonographically relevant structures ("landmarks") in open hernia repair are the anterior-superior iliac spine, pubic tubercle, Camper´s fascia (superficial layer of the superficial abdominal fascia), External oblique aponeurosis, Internal oblique muscle, Transversus abdominis muscle, superficial inguinal ring, external spermatic fascia, cremasteric fascia with cremaster muscle fibers, internal spermatic fascia, cremasteric vein (=external spermatic vein = "blue line"), ductus deferens, pampiniform plexus, inguinal ligament and the inferior epigastric vessels.

CONCLUSION

A detailed understanding of inguinal anatomy is an indispensable basic requirement for all surgeons to perform inguinal ultrasonography as well as open inguinal hernia repair, avoiding complications, especially postoperative inguinodynia.

Are single-injection erector spinae plane block and multiple-injection costotransverse block equivalent to thoracic paravertebral block?

BACKGROUND

Thoracic paravertebral block (TPVB) is considered the gold standard for hemithoracic regional anaesthesia. Erector spinae plane block (ESPB) is a new posterior thoracic wall block. Multiple-injection costotransverse block (MICB) mimics TPVB but with injection points within the thoracic intertransverse tissue complex and posterior to the superior costotransverse ligament. We aimed to compare the spread of injectate into the thoracic paravertebral space (TPVS) resulting from single-injection ESPB and MICB, respectively, with TPVB.

METHODS

Ten soft-embalmed cadavers were utilised. In five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided single-injection ESPB or single-injection TPVB; vice versa on the other side. In another five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided MICB or multiple-injection TPVB. About 20 mL of dye was injected in each hemithorax with all techniques.

RESULTS

With TPVB, the dye was consistently present in the TPVS with concomitant epidural spread in the majority of cases. The injectate spread into the TPVS with ESPB (60%) and MICB (100%). MICB consistently stained the ventral rami (T1-7), communicating rami and thoracic sympathetic trunk without epidural spread. Dissection after MICB revealed dye spread into the TPVS via the costotransverse foramina and along the dorsal branches of the posterior intercostal veins.

CONCLUSIONS

Consistent spread of dye into the TPVS colouring the ventral rami, the communicating rami, and the sympathetic trunk was observed with MICB; in this respect equivalent to TPVB. ESPB exhibited only partial success and was not equivalent to TPVB. No epidural spread was found with neither MICB nor ESPB.

Randomized trial of ultrasound-guided superior cluneal nerve block

BACKGROUND AND OBJECTIVES

The superior cluneal nerves originate from the dorsal rami of primarily the upper lumbar spinal nerves. The nerves cross the iliac spine to innervate the skin and subcutaneous tissue over the gluteal region. The nerves extend as far as the greater trochanter and the area of innervation may overlap anterolaterally with the iliohypogastric and the lateral femoral cutaneous (LFC) nerves. A selective ultrasound-guided nerve block technique of the superior cluneal nerves does not exist. A reliable nerve block technique may have application in the management of postoperative pain after hip surgery as well as other clinical conditions, for example, chronic lower back pain. In the present study, the primary aim was to describe a novel ultrasound-guided superior cluneal nerve block technique and to map the area of cutaneous anesthesia and its coverage of the hip surgery incisions.

METHODS

The study was carried out as two separate investigations. First, dissection of 12 cadaver sides was conducted in order to test a novel superior cluneal nerve block technique. Second, this nerve block technique was applied in a randomized trial of 20 healthy volunteers. Initially, the LFC, the subcostal and the iliohypogastric nerves were blocked bilaterally. A transversalis fascia plane (TFP) block technique was used to block the iliohypogastric nerve. Subsequently, randomized, blinded superior cluneal nerve blocks were conducted with active block on one side and placebo block contralaterally.

RESULTS

Successful anesthesia after the superior cluneal nerve block was achieved in 18 of 20 active sides (90%). The area of anesthesia after all successful superior cluneal nerve blocks was adjacent and posterior to the area anesthetized by the combined TFP and subcostal nerve blocks. The addition of the superior cluneal nerve block significantly increased the anesthetic coverage of the various types of hip surgery incisions.

CONCLUSION

The novel ultrasound-guided nerve block technique reliably anesthetizes the superior cluneal nerves. It anesthetizes the skin posterior to the area innervated by the iliohypogastric and subcostal nerves. It improves the anesthetic coverage of incisions used for hip surgery. Among potential indications, this new nerve block may improve postoperative analgesia after hip surgery and may be useful as a diagnostic block for various chronic pain conditions. Clinical trials are mandated.

TRIAL REGISTRATION NUMBER

EudraCT, 2016-004541-82.

Clinical-anatomic mapping of the tarsal tunnel with regard to Baxter's neuropathy in recalcitrant heel pain syndrome: part I

Purpose

Neuropathy of the Baxter nerve (BN) seems to be the first cause of the heel pain syndrome (HPS) of neurological origin.

Methods

41 alcohol–glycerol embalmed feet were dissected. We documented the pattern of the branches of the tibial nerve (TN) and describe all relevant osteofibrous structures. Measurements for the TN branches were related to the Dellon–McKinnon malleolar-calcaneal line also called DM line (DML) for the proximal TT and the Heimkes Triangle for the distal TT. Additionally, we performed an ultrasound-guided injection procedure of the BN and provide an algorithm for clinical usage.

Results

The division of the TN was 16.4 mm proximal to the DML. The BN branches off 20 mm above the DML center or 30 mm distally to it. In most of the cases, the medial calcaneal branch (MCB) originated from the TN proximal to the bifurcation. Possible entrapment spots for the medial and lateral plantar nerve (MPN, LPN), the BN and the MCB are found within a circle of 5 mm radius with a probability of 80%, 83%, and 84%, respectively. In ten out of ten feet, the US-guided injection was precisely allocated around the BN.

Conclusions

Our detailed mapping of the TN branches and their osteofibrous tubes at the TT might be of importance for foot and ankle surgeons during minimally invasive procedures in HPS such as ultrasound-guided ankle and foot decompression surgery (UGAFDS).

Spread of injectate around hip articular sensory branches of the femoral nerve in cadavers

BACKGROUND

Anatomical knowledge dictates that regional anaesthesia after total hip arthroplasty requires blockade of the hip articular branches of the femoral and obturator nerves. A direct femoral nerve block increases the risk of fall and impedes mobilisation. We propose a selective nerve block of the hip articular branches of the femoral nerve by an ultrasound-guided injection in the plane between the iliopsoas muscle and the iliofemoral ligament (the iliopsoas plane). The aim of this study was to assess whether dye injected in the iliopsoas plane spreads to all hip articular branches of the femoral nerve.

METHODS

Fifteen cadaver sides were injected with 5 mL dye in the iliopsoas plane guided by ultrasound. Dissection was performed to verify the spread of injectate around the hip articular branches of the femoral nerve.

RESULTS

In 10 dissections (67% [95% confidence interval: 38-88%]), the injectate was contained in the iliopsoas plane staining all hip articular branches of the femoral nerve without spread to motor branches. In four dissections (27% [8-55%]), the injection was unintentionally made within the iliopectineal bursa resulting in secondary spread. In one dissection (7% [0.2-32%]) adhesions partially obstructed the spread of dye.

CONCLUSION

An injection of 5 mL in the iliopsoas plane spreads around all hip articular branches of the femoral nerve in 10 of 15 cadaver sides. If these findings translate to living humans, injection of local anaesthetic into the iliopsoas plane could generate a selective sensory nerve block of the articular branches of the femoral nerve without motor blockade.

Teaching concepts in ultrasound-guided regional anesthesia

PURPOSE OF REVIEW

Ultrasound-guided regional anesthesia is a challenging, complex skill and requires competence in teaching. The aim of this study was to review current literature on identification of education and learning of ultrasound-guided regional anesthesia and to summarize recent findings on teaching concepts.

RECENT FINDINGS

Several teaching programs have been described and implemented into daily routine. Factors relevant to current practice are the knowledge of sonoanatomy, the acquisition of manual skills, the teaching ability, and the feedback given to the trainee. Simulation is a rapidly growing field and is supported by the development of phantoms. Needle visualization is one of the core competencies that is necessary for successful ultrasound-guided procedures and could be supported by technical developments in the future to improve teaching concepts.

SUMMARY

Although a lot of key questions cannot be answered by the latest study results, some interesting findings were able to improve existing education programs. These results should be tailored to the individual need of a trainee, and the effects of improved training programs on patient safety and quality of care have to be investigated. The see one, do one, teach one approach is obsolete and should be abandoned.

The supraorbital region revisited: An anatomic exploration of the neuro-vascular bundle with regard to frontal migraine headache

BACKGROUND

Recent findings on the pathogenesis of frontal migraine headache support, besides a central vasogenic cause, an alternative peripheral mechanism involving compressed craniofacial nerves. This is further supported by the efficiency of botulinum toxin injections as a new treatment option in frontal migraine headache patients.

METHODS

The supraorbital regions of 22 alcohol-glycerine-embalmed facial halves of both sexes were dissected. Both the supratrochlear and supraorbital nerves (STN and SON, respectively) were identified, and their relationship with the corrugator supercilii muscle (CSM) was investigated by dissection and ultrasound. The course of both nerves was defined, and the interaction between the supraorbital artery (SOA) and SON was determined.

RESULTS

We discovered a new possible compression point of the STN passing through the orbital septum and verified previously described compression points of both STN and SON. Osteofibrous channels used by the STN and SON were found constantly. We described the varying topography of the STN and CSM, the SON and CSM, and the SON and SOA. Further, we provide an algorithm for the ultrasound visualization of the supraorbital neurovascular bundle.

CONCLUSION

Our data support the hypothesis of a peripheral mechanism for frontal migraine headache because of following potential irritation points: first, the CSM is constantly perforated by the SON and frequently by the STN; second, the topographic proximity between SOA and SON and the osteofibrous channels is used by the SON and STN; and third, the STN passes through the orbital septum.

Benefits and Pitfalls of Cadavers as Learning Tool for Ultrasound-guided Regional Anesthesia

Ultrasound-guided regional anesthesia (UGRA), like other basic skills, should be learnt in a simulation laboratory before performing on the patient. Cadavers provide an ideal tool for learning sonoanatomy and skills required for performing UGRA. On the basis of preservation technique used, the cadavers can be formalin embalmed cadavers, Thiel cadavers (soft cadavers), and fresh frozen cadavers. We compared three types of cadavers for performing ultrasound-guided upper and lower limb blocks. We observed that fresh frozen and Thiel cadavers were less smelling and had more realistic appearance as compared to formalin embalmed cadavers. It was seen that Thiel cadavers were more flexible and hence, rotation of neck, shoulder and knee was easier. Although images seen in most cadavers were comparable with live subjects but, Thiel cadavers provided more realistic model.

Ultrasound-Guided Approach for L5 Dorsal Ramus Block and Fluoroscopic Evaluation in Unpreselected Cadavers

BACKGROUND AND OBJECTIVES

Medial branch blocks are frequently performed to diagnose lumbar facet-joint-mediated pain. Ultrasound guidance can increase practicability and eliminate exposure to ionizing radiation when compared with fluoroscopy. However, ultrasound-guided L5 dorsal ramus block, which, together with L4 medial branch block is necessary to anesthetize the most commonly affected facet joint L5/S1, has not been described so far. The objective of this study was to develop a technique and to evaluate its accuracy with standard fluoroscopy in unpreselected cadavers.

METHODS

Twenty ultrasound-guided L5 dorsal ramus block approaches were performed with a new oblique out-of-plane technique in a rotated cross-axis view bilaterally in 10 cadavers. After checking the needle position in a second perpendicular sonographic plane, the final needle position was confirmed with conventional fluoroscopy by an independent observer.

RESULTS

All cadavers had significant degenerations of the lumbar spine, and 5 of them had moderate to severe spondylolisthesis. Skin-to-target distances were 42 ±7 mm. Sixteen L5 dorsal ramus block attempts were located at the exact radiological target, 1 was slightly too lateral, and 3 were slightly too caudal (3-10 mm away). The overall success rate in unpreselected cadavers reached 80% (95% confidence interval, 56%-94%) and in the subgroup of corpses without spondylolisthesis 100% (95% confidence interval, 69%-100%).

CONCLUSIONS

This is the first study to show that ultrasound-guided L5 dorsal ramus block is accurate and feasible in the absence of significant spondylolisthesis when performed with an oblique out-of-plane technique.

New laparoscopic approach to the pudendal nerve for neuromodulation based on an anatomic study

AIMS

The aim was to develop a new laparoscopic technique for placement of a pudendal lead.

METHODS

Development of a direct, feasible and reliable minimal-invasive laparoscopic approach to the pudendal nerve (PN). Thirty-one embalmed human specimens were dissected for the relevant anatomic structures of the pelvis. Step-by-step documentation and analysis of the laparoscopic approach in order to locate the PN directly in its course around the medial part of the sacrospinous ligament and test this approach for feasibility. Landmarks for intraoperative navigation towards the PN as well as the possible position of an lead were selected and demonstrated.

RESULTS

The visible medial umbilical fold, the intrapelvine part of the internal pudendal artery, the coccygeus muscle and the sacrospinous ligament are the main landmarks. The PN traverses the medial part of the sacrospinous ligament dorsally, medially to the internal pudendal artery. The medial part of the sacrospinous ligament has to be exposed in order to display the nerve. An lead can be placed ventrally on the nerve or around it, depending on the lead type or shape.

CONCLUSIONS

A precise and reliable identification of the PN by means of laparoscopy is feasible with an easy four-step approach: (1) identification of the medial umbilical fold; (2) identification of the internal iliac artery; (3) identification of the internal pudendal artery and incision of the coccygeus muscle ('white line', arcuated line); and (4) exposition of the medial part of the sacrospinous ligament to display the PN.

The nonrecurrent laryngeal nerve: A clinical anatomic mapping with regard to intraoperative neuromonitoring

BACKGROUND

We investigated the nonrecurrent inferior laryngeal nerve (nrILN), an important variant in the course of the inferior laryngeal nerve (ILN; 0.5-6.0%). Its importance was demonstrated in a clinical case as well as in cadaver specimens, and the pattern was identified with intraoperative neuromonitoring (IONM).

METHODS

The ILN and the presence of an nrILN were investigated in 36 formaldehyde-embalmed specimens. Our anatomic findings showed differences in the anatomic course of the ILN and thus produced possible explanations for different IONM signals that would correlate with differences in the anatomic course of the ILN. Preoperative ultrasonographic evaluation of the brachiocephalic trunk and the recurrent laryngeal nerve were used for the exclusion or identification of an nrILN, respectively.

RESULTS

We found 2 nrILNs (ascending, horizontal; 6%) in the anatomic specimens. These 2 specimens each showed an aberrant right subclavian artery (lusorial artery) and were, therefore, associated with the absence of a brachiocephalic trunk. The intraoperative case displayed a descending nrILN. Signals derived from the vagus nerve were positive if derived proximal to and negative if derived distal to the branching of an nrILN. By ultrasonographic identification of a normal brachiocephalic trunk, an nrILN could be excluded.

CONCLUSION

Surgeons need a working knowledge about nrILNs to avoid recurrent nerve palsy and should be familiar with all the possible course variations in the ILN when IONM signals are absent with vagal stimulation. Moreover, endocrine surgeons need to be able to interpret correctly negative as well as positive signals. Preoperative ultrasonography should ideally be performed, because the presence of a normal brachiocephalic trunk is a quick method to exclude or identify a nrILN.

Histological confirmation of needle tip position during ultrasound-guided interscalene block: a randomized comparison between the intraplexus and the periplexus approach

PURPOSE

Ultrasound-guided interscalene block can be performed using either periplexus or intraplexus needle placement. In this novel study, we histologically examined the needle tip position in relation to the neural tissues with the two techniques. Our objective was to investigate the variable risk of subepineurial needle tip placement resulting from the two ultrasound-guided techniques.

METHODS

In an embalmed cadaveric model, periplexus or intraplexus interscalene injections were performed with the side, order, and technique assigned randomly. Under real-time ultrasound guidance, the block needle was placed next to the hyperechoic layer of the plexus (periplexus) or between the hypoechoic nerve roots (intraplexus). Once positioned, 0.1 mL of black acrylic ink was injected. The brachial plexus tissues were then removed and histology sections were prepared and then coded in order to blind two reviewers to group allocation. The area of ink staining was used to determine needle tip location, and the groups were compared for the presence of subepineurial ink.

RESULTS

Twenty-six cadavers had each of the blocks performed on either brachial plexus (i.e., 52 injections). No subepineurial ink deposits were observed in the periplexus group (0%), but subepineurial ink deposition was observed in 3/26 (11.5%) intraplexus injections (odds ratio, 0; 95% confidence interval, 0 to 2.362; P = 0.235). Furthermore, in the intraplexus group, two (of the three) subepineurial ink deposits were observed under the perineurium.

CONCLUSION

Although our study was somewhat underpowered due to a lower than previously reported rate of subepineurial needle tip positioning, our results suggest that there may be an increased likelihood of subepineurial needle tip position with the intraplexus approach. The periplexus technique resulted in no subepineurial spread of ink, suggesting that this approach may be less likely to result in mechanical trauma to nerves from direct needle injury.

Simulation in teaching regional anesthesia: current perspectives

The emerging subspecialty of regional anesthesiology and acute pain medicine represents an opportunity to evaluate critically the current methods of teaching regional anesthesia techniques and the practice of acute pain medicine. To date, there have been a wide variety of simulation applications in this field, and efficacy has largely been assumed. However, a thorough review of the literature reveals that effective teaching strategies, including simulation, in regional anesthesiology and acute pain medicine are not established completely yet. Future research should be directed toward comparative-effectiveness of simulation versus other accepted teaching methods, exploring the combination of procedural training with realistic clinical scenarios, and the application of simulation-based teaching curricula to a wider range of learner, from the student to the practicing physician.

A low cost training phantom model for radio-guided localization techniques in occult breast lesions

Radio-guided localization (RGL) for identifying occult breast lesions has been widely accepted as an alternative technique to other localization methods, including those using wire guidance. An appropriate phantom model would be an invaluable tool for practitioners interested in learning the technique of RGL prior to clinical application. The aim of this study was to devise an inexpensive and reproducible training phantom model for RGL. We developed a simple RGL phantom model imitating an occult breast lesion from inexpensive supplies including a pimento olive, a green pea and a turkey breast. The phantom was constructed for a total cost of less than $20 and prepared in approximately 10 min. After the first model's construction, we constructed approximately 25 additional models and demonstrated that the model design was easily reproducible. The RGL phantom is a time- and cost-effective model that accurately simulates the RGL technique for non-palpable breast lesions. Future studies are warranted to further validate this model as an effective teaching tool.