ThinPrep and Conventional Smear Cyto-Preparation FNA - Essay Example

Literature Review of Comparison between the ThinPrep and Conventional Smear Cyto-preparation FNA Literature Review of Comparison between the ThinPrep and Conventional Smear Cyto-preparation FNA Diagnostic accuracy in the technique of Fine Needle Aspiration has been a major concern for researchers for decades. Necessarily studies on the Fine Needle Aspiration Biopsies have had to focus on other features of conveniences such as cost effectiveness, time consumed in the whole process, the potential pitfalls, etc. In the field of diagnosis several procedures of FNA were innovated in pursue of accuracy, but none of them, except ThinPrep was proved to be qualified enough to be competent with the conventional one. The points of accuracy of FNA are such that they never yield any clear demarcation or any standard at which the accuracy of the technique can be measured as well as defined. As a result, the pathologists and clinicians are to depend on the conveniences of a particular method that is most pertinent to the circumstance. A series of researches was led on the comparative diagnostic accuracy of the two techniques of FNA and their popularity among the clinicians and the pathologists (Frost et al, 1998). An analysis of the studies that have been led on the evaluation and the development of the techniques of Fine Needle Aspiration show an encouraging support for the ThinPrep technique of Fine Needle Aspiration Biopsies and trace the significant attempts in avoiding the pitfalls in the technique. In general, researchers are of the opinion that the accuracy of FNA at any site in the head and neck depends on both the skill and knowledge of the sites of the individual who will perform the FNA biopsies. As Layfield (2007) says, ‘Studies have shown that FNA is most accurate when the individual interpreting the FNA is the same individual who obtained the aspirate material’ (p. 798). In order to evaluate the performance of the FNA at the sites in the head and neck studies have had to revolve around the following questions: a. Is FNA the best procedure of diagnosis for lesions in the head and neck? b. What are the potential diagnostic challenges associated with FNA? c. Which features of FNA are most alluring: accuracy, cost effectiveness, rapid performance, etc.? d. What are the potential artifacts and pitfalls of FNA involving conventional Direct Smear and ThinPrep techniques? e. To find whether one technique is more effective than the other technique at a particular site in the head and neck? f. What are the cyto-morphologic and cyto-logic features of FNA involving Conventional Smear technique and the ThinPrep technique? As far as the procedure of biopsy involves the obtainment of tissue, cell, or other specimen for diagnostic purposes, Fine Needle Aspiration has always played a crucial role as an initial technique of collecting them from a number of sites of human body. Indeed FNA is applied at a number of sites within the head and neck. The pressing appeal of the technique lies in several factors such rapidity, inexpensiveness, high convenience, low morbidity and necessarily in a relatively high diagnostic accuracy (Lester 2007). The amenability that areas in the head and neck show to this technique is mainly due to its capability to overcome the structural obstructions and barriers of the sites such as intra-oral lesions, thyroid, salivary, cervical masses and nodules, lesions in the Para-spinal area, etc. where the application of FNA is more effective than any other techniques. In order to evaluate the efficacy of FNA biopsies in the head neck lesions, researchers have focused in the efficacy of FNA as well as the innovations of various techniques in the procedure. Literature on the efficacy of FNA has shown a clear agreement that FNA is the most effective way of diagnosis at the sites in the head and neck. In an article ‘Diagnostic Value and Cost-Effectiveness of On-Site Evaluation of Fine-Needle Aspiration Specimens: Review of 5,688 Cases’ Nasuti et al (2002) claim FNA as a proven safe, cost-effective, and easy-to-perform way of biopsies for diagnosis. Meanwhile they further added the criteria that the success of FNA mainly depends on the adequacy of the celularity of specimen and on the skill of the clinicians and the cyto-pathologists in preparing the specimen (pp. 1-3). In this regard they opine that onsite evaluation of FNA aspirate is helpful for the determination of the adequacy of the celularity if the specimen. At this point, though not directly, Layfield agrees with the Nasuti et al, as he comments, “Diagnostic accuracy is dependent on the site of aspiration as well as the skill of the individual performing and interpreting the FNA” (798). As accuracy is the prime concern of any FNA, the researchers are primarily concerned with the any technique that yields more results that are accurate. In this regard, cost-effectiveness comes as an aftermath of the accuracy. Accordingly, the studies showed that the cost of FNA fluctuates with the oscillations of the use of techniques in FNA. However, the challenges that techniques of FNA pose grab the prime concern of the cyto-pathologists. Depending on the sites in the head and neck, the challenges for FNA may vary. Despite the presence of the numerous techniques, the conventional smear method of FNA is often regarded as the best way to collect specimen. Yet various other methods for collecting FNA aspiration and preparation may prove to be pertinent to various situations. Often a lot of experience is necessary to choose the proper technique for a particular. Ford et al (2002) comments, ‘The ultimate diagnostic goal of FNA is accuracy. Secondary goals are to achieve as much safety, speed, and cost effectiveness as possible’ (p. 558). Researches show that Conventional Direct Smear method and ThinPrep are the two of the most competent techniques of FNA to meet these two goals at a time. In a research article, ‘Comparison of ThinPrep versus conventional smear cyto-preparatory techniques’ Ford et al (2002) comment that ThinPrep for FNA specimen aspiration and preparation is applicable to the ‘salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions’ (p. 554). Their research significantly reveals the site-oriented usability features of ThinPrep. At the same time, they assert that Conventional Smears Technique is more effective for non-metastatic lymphoid lesions. They cautiously assert that the uses of both Conventional Cyto-preparatory and ThinPrep Techniques can be complementary to each other in several cases of bloody aspirates, avoiding the patients’ blood-borne infectious diseases, or for facilitating an inexperienced clinician. Especially at the thyroid around the head and neck area of human body, the aspirate may be non-diagnostic up to 32% of FNAs. The aspirates may be non-diagnostic due to the inadequacy of cellularity of specimen (Ford et al 2002). In Ford et al’s paper, several questions regarding the comparison between ThinPrep Techniques and the Conventional cyto-preparatory techniques were in focus of their study. First the question that was addressed in the paper is: which one of the two technique is more accurate than the other? And what are the convenient features of the two technique? Then another question was investigated: which one is superior to the other in an overall consideration? For this investigation, 236 FNA involving both conventional smear and ThinPrep Techniques in 209 patient-cases of FNA were investigated. From this investigation, Ford et al reached the conclusion that ThinPrep Technique for FNA was less assisted by the air-drying artifact and mechanical distortions. About 63 percent of the Total FNA specimen using Conventional Direct Smear Technique was proved diagnostic, whereas 55 percent of the FNA specimen was diagnostic. As to the preference of the pathologists and clinicians for the two techniques, the findings of Ford et al’s (2002) paper was as following: ‘When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cyto-preparatory technique for most head and neck masses’ (p. 798). The research appeared to win its credibility by employing an apparently flawless method. Both of the conventional Smear and the ThinPrep Techniques were applied to obtain the aspirates from the head and neck masses. In order to avoid the effect of one technique on the other due to their order of use Ford et al attempted to randomize the order of applications of the techniques. If the specimen using one technique was obtained adequately, the other technique was applied. For the conventional Smear technique, the aspirate was taken up to the hub of the needle in order to avoid the air-drying, subsequently expressed on slides, and smeared. Once smeared, ‘the slides were immersed in a 95% ethyl alcohol solution.’ (Ford et al, 2002, p. 555) For the ThinPrep technique once obtained, the needle and the syringe were rinsed in ‘30 ml of a methanol-based preservative solution.’ (Ford et al, 2002, p. 556) Then after centrifuging the specimen, the supernatant was discarded and transferred to the Cytyc or other preservative. In another research article ‘Thin layer compared to direct smear in thyroid fine needle aspiration’ Scurry and Duggan’s investigation into the comparison of the use of Thin Layer Tech with the Smears in an unbiased and natural clinical environment. Scurry and Duggan principally focused on the accuracy and cost effectiveness of FNA using both of the Thin Layer Technique and the Smear technique. Indeed, what they found was with a clear agreement with the most other researches on the accuracy rates of the techniques. In this study, also the accuracy rate of Thin Layer Technique was negligibly lower than the Smear technique. As Scurry and Duggan (1999) assert, ‘We have taken advantage of largely unchanged clinical, laboratory….to concentrate on answering the single question of whether thin layer produces better or worse thyroid aspirates for diagnostic purposes’ (p. 105). Indeed though some difference between the accuracy rates of the two techniques was found, Scurry and Duggan tended to defy the quality difference between the techniques. Their study showed that Thin Layer aspirates demonstrate a higher rate of benignity (24% up to 31%), ‘a lower proportion of inadequate specimens (50% down to 41%), and most importantly, a lower false-negative rate (9% down to 3%).’ (Scurry and Duggan, 1999, p. 107) Though the method of this research was the intended one, its limitation is the method itself. As the study was targeted to investigate aspirates from ThinPrep in an unbiased commercial environment, the patients at the Foothills Hospital from 1994 to 1997 were based as target bearers of the investigation. The patients who underwent the FNA using ThinPrep from were excluded in order to attain more perfection, because at the beginning of the duration the FNA techniques were changed from the conventional to the ThinPrep. In an average 2 or 3 passes were used every nodule and aspirates were obtained with a 23 gauge needle based onto a 10-cc syringe. For the patients who underwent the ThinPrep of Thyroid FNA at least one slide was used to prepare air-dried direct smear for Giemsa staining. A portion of the aspirates was fixated by 95% alcohol solution for Pap staining. In case of cyst presence in the aspirate, Cytospin technique was used. Indeed the Limitation of this study was that it was not able to use both of the two techniques for the same patient. As a result, a thorough comparison was impeded. For the Cyto-preparation of FNA from the Head and neck masses, the ThinPrep was introduced just to overcome the impediment that a computerized cyto-detection system faces when analyzing the FNA specimen produced using the Conventional smear. Indeed until the technique if ThinPrep FNA was targeted to meet both of the effectiveness and the cost effectiveness. Pap test often appears to be a laborious task for the pathologists. Also the Pap smear is prone to produce false-negative results at a higher rate due to the inexperience of the individuals who are involved with the job. In spite of the computer depended FNA processing system was innovated in the cyto-pathology, the problem was that the new system requires a more effective preparation of FNA in order to perform the detection properly. Eventually the new system was helpful in many regards to avoid the problems that exist with the conventional Smear Technique, as Ljung (2008) says, ‘It became clear that humans found the new preparations easier to read and achieved better screening results with the liquid-based preparation compared with traditional smears’ (p. 144). Studies on the comparison between the two techniques showed that the technical research is prone to prove the technical accuracy of the smears technique, researchers have concluded about the superiority of one technique over the other differently from different points of view. In a research article, Fulya et al (2008) were able to prove the superiority of ThinPrep technique from the morphologic point. In their research, the cyto-morphologic characteristics of ThinPrep and Conventional Smear FNA of the head and neck lesions were compared and the authors concluded that cellularity and the cyto-plasmic details of the conventions smears were higher than the ThinPrep FNA was. However, the authors also commented, ‘TP preparations were superior to CS as for absence of blood and necrosis’ (Fulya et al, 2008, p. 161). Though the diagnostic accuracy of the conventional smear was proved technically, the convenience-related aspects of ThinPrep was assert in a firm way. Fulya et al commented that ThinPrep FNA specimens could easily be interpreted, as the cells were scattered within a small area and less overlapped. Though there is not any major controversy on the accuracy of Thin-Layer Preparation Technique for Fine Needle Aspiration compared with the conventional Direct Smear method and though the Thin-Layer Preparation technique of FNA is assisted with a set of convenient utility features, the certainty that goes with the conventional method has retained its appeal to the clinicians and pathologists (Alaa, Liu & Khaphaji, 2001). In this regard, Ljung (2008) comments, ‘Most of these studies found that smears were superior, providing fewer non-diagnostic specimens and/or providing a higher proportion of definitive and/or accurate diagnoses using histology as a gold standard’ (p. 146). The conveniences that the Thin-Layer Prep for Fine Needle Aspiration Method provides are with a modernizing tone, void of the flabbiness of the conventional one gradually are winning the appraisal of the frequent users of FNA. References Alaa M. A. Liu, J. & Al-Khaphaji, M. B 2001, ‘Cytologic Artifacts and Pitfalls of Thyroid Fine-Needle Aspiration Using ThinPrep: A Comparative Retrospective Review’, Cancer (Cancer Cyto-Pathology), American Cancer Society, vol. 93, No. 3 Ljung, B 2008, ‘Thyroid Fine-Needle Aspiration: Smears Versus Liquid-based Preparations’, Cancer (Cancer Cyto-Pathology), vol. 114, no. 3 Ford et al 2002, ‘Comparison of ThinPrep versus conventional smear cytopreparatory techniques for fine-needle aspiration specimens of head and neck masses’, Otolaryngology–Head and Neck Surgery, vol. 126, no. 5 Frost Et al 1998, ‘Utility of Thin-Layer Preparations in Thyroid Fine-Needle Aspiration’, Cancer (Cancer Cyto-Pathology), American Cancer Society Vol. 84, N. 1 Fulya et al 2008, ‘Comparison of ThinPrep and conventional smears in head and neck fine needle aspiration cytology’, Turkish Journal of Pathology, vol. 24, no, 3, pp: 159-165 Layfield, J. L 2007, ‘Fine-Needle Aspiration in the Diagnosis of Head and Neck Lesions: A Review and Discussion of Problems in Differential Diagnosis’, Diagnostic Cytopathology, Willy Inter-Science, vol. 35, No. 12 Nasuti, J. F., YU G., Boudousquie, A. & Gupta. P 1999, ‘Diagnostic value of lymph node fine needle aspiration cytology: an institutional experience of 387 cases observed over a 5-year period’, Cytopathology, Blackwell Science Ltd, vol. 11, pp. 18–31 Nasuti, J. F. & Gupta, K. P 2001, ‘Diagnostic Value and Cost- Effectiveness of On-Site Evaluation of Fine-Needle Aspiration Specimens: Review of 5,688 Cases’, Diagnostic Cytopathology, Willy Inter-Science, Vol 27, No 1 Scurry, P. J & Duggan, A. M 1999, ‘Thin layer compared to direct smear in thyroid fine needle aspiration’, Blackwell Science Ltd, Cytopathology, vol. 11, pp. 104–115 Read More