Chung K C, Greenfield M L, Walters M
University of Michigan Medical Center and Department of Clinical Research, St. Joseph Mercy Hospital, Ann Arbor 48109-0340, USA.
Plast Reconstr Surg. 1998 Sep;102(3):689-95. doi: 10.1097/00006534-199809030-00011.
Despite numerous studies advocating ultrasonography and magnetic resonance imaging (MRI) in the evaluation of women with possible silicone breast implant rupture, an appropriate algorithm has not been published for the optimal use of these tests. To derive a diagnostic algorithm using ultrasonography and MRI, we applied a decision-analytic model using Bayes' theorem to calculate the probabilities of implant rupture for three representative patient characteristics. A Medline search was conducted to identify literature related to the diagnosis of silicone breast implant rupture using ultrasonography and MRI since 1994. Also examined were case series of implant rupture to obtain rupture prevalence in cases in which rupture was dependent on patient presentation (symptomatic versus asymptomatic) and dependent on implant age. Test characteristics (sensitivity and specificity) and implant rupture prevalence are used to calculate the probability of rupture by using Bayes' theorem. These probabilities are derived for three patient categories: (1) asymptomatic, (2) symptomatic with implant age < or = 10 years, and (3) symptomatic with implant age >10 years. In asymptomatic patients, the pretest rupture prevalence is 6.5 percent. If a screening ultrasonography shows no rupture, the probability of rupture drops to 2.2 percent. If ultrasonography shows rupture, the probability of true rupture increases to 37.8 percent. Removal of implants in this setting will result in a high probability of extracting normal implants. However, if MRI after the ultrasonography shows rupture, the probability of true rupture increases to 86 percent, which gives better assurance of removing true-ruptured implants. In "symptomatic" patients (i.e., breast asymmetry, capsular contracture) with implants < or = 10 years old, the prevalence of rupture is estimated at 31 percent. If ultrasonography shows no rupture, the probability of rupture drops to 16 percent. If ultrasonography shows rupture, the probability of true rupture is 79.7 percent, and this probability increases to 97.5 percent if a follow-up MRI also shows rupture. In symptomatic patients with implants >10 years old, the prevalence of rupture is estimated at 64 percent. If ultrasonography shows rupture, the probability of true rupture increases to 94 percent, and no further diagnostic work-up is necessary. In an asymptomatic patient who is worried about the integrity of her implants, ultrasonography should be used as an initial diagnostic test because of its lower cost. If ultrasonography shows no rupture, no further work-up is necessary. If ultrasonography shows rupture, the low probability (37.8 percent) of true rupture requires a confirmatory test using MRI. In "symptomatic" patients, the high prevalence of rupture markedly raises the posttest probability of rupture for positive ultrasonography findings. Particularly in "symptomatic" patients with implants >10 years old, the high posttest probability of rupture (94 percent) with a positive ultrasonography obviates the need for any further diagnostic testing. This diagnostic algorithm will assist plastic surgeons in counseling women who are worried about the integrity of their silicone breast implants.
尽管有大量研究提倡使用超声检查和磁共振成像（MRI）来评估可能发生硅胶乳房植入物破裂的女性，但尚未发表关于如何最佳使用这些检查的合适算法。为了推导使用超声检查和MRI的诊断算法，我们应用了一种基于贝叶斯定理的决策分析模型，来计算三种具有代表性患者特征的植入物破裂概率。我们进行了Medline检索，以找出自1994年以来与使用超声检查和MRI诊断硅胶乳房植入物破裂相关的文献。还研究了植入物破裂的病例系列，以获取破裂发生率，该发生率取决于患者表现（有症状与无症状）以及植入物使用年限。利用检查特征（敏感性和特异性）以及植入物破裂发生率，通过贝叶斯定理来计算破裂概率。这些概率是针对三类患者得出的：（1）无症状患者，（2）植入物使用年限≤10年且有症状的患者，（3）植入物使用年限>10年且有症状的患者。在无症状患者中，检查前的破裂发生率为6.5%。如果筛查超声检查显示没有破裂，破裂概率降至2.2%。如果超声检查显示破裂，真正破裂的概率升至37.8%。在此情况下取出植入物将导致取出正常植入物的可能性很高。然而，如果超声检查后进行的MRI显示破裂，真正破裂的概率升至86%，这能更好地确保取出真正破裂的植入物。在植入物使用年限≤10年的“有症状”患者（即乳房不对称、包膜挛缩）中，破裂发生率估计为31%。如果超声检查显示没有破裂，破裂概率降至16%。如果超声检查显示破裂，真正破裂的概率为79.7%，如果后续MRI也显示破裂，该概率将升至97.5%。在植入物使用年限>10年的有症状患者中，破裂发生率估计为64%。如果超声检查显示破裂，真正破裂的概率升至94%，无需进一步的诊断检查。对于担心其植入物完整性的无症状患者，由于超声检查成本较低，应将其作为初始诊断检查。如果超声检查显示没有破裂，则无需进一步检查。如果超声检查显示破裂，真正破裂的低概率（37.8%）需要使用MRI进行确认性检查。在“有症状”患者中，破裂的高发生率显著提高了超声检查阳性结果时破裂的检查后概率。特别是在植入物使用年限>10年的“有症状”患者中，超声检查阳性时破裂的高检查后概率（94%）使得无需任何进一步的诊断检查。这种诊断算法将有助于整形外科医生为担心其硅胶乳房植入物完整性的女性提供咨询。
