本帖最後由 lsc0019 於 2009-5-27 00:30 編輯
作者：Alice McCarthy
出處：WebMD醫學新聞
May 11, 2009 (波士頓) —一篇使用電腦斷層大腸鏡檢查(CTC)的研究發現，此技術可以在將近92%的案例中實際偵測出小達6mm的息肉。此發現發表於美國放射線醫學會(ARRS)2009年會中。
這項由威斯康辛大學醫學院進行的研究，CTC(或稱為虛擬大腸鏡檢查)偵測出479名大腸直腸篩檢病患739個病灶中的667處(91.6%)。
本研究最初有5,124名病患使用CTC篩檢，其中，639名病患(整體的12.5%)發現有6mm以上的息肉；其中，479名病患接受後續的光學大腸鏡檢查進一步確認，並以大腸鏡息肉切除術確認陽性預測值(PPV)。
主要研究者、威斯康辛大學醫學暨公共衛生學院的Steven Wise醫師向Medscape Radiology表示，我認為我們的資料支持使用CTC作為大腸癌的初步篩檢工具；我們認為它可以作為初步篩檢檢測，讓CTC篩檢陽性的病患可以接受適當的大腸鏡檢查與後續的大腸鏡息肉切除術。
他表示，為了作為有效的篩檢工具，CTC必須不只可以敏感地偵測臨床發現的病灶，如本研究的6mm以上的息肉，也要有低的偽陽性率以及與光學大腸鏡的高一致性。
這項研究發現，CTC的PPV並未因為息肉大小而變。10mm以上的息肉有將近92.7%被CTC偵測。6-9mm息肉的偵測率差不多有90.1%。不過，研究者發現，息肉型態對於不同的PPV發現有所影響。分類為腫塊病灶或地毯狀病灶者，可以100%被偵測。不過，扁平病灶只偵測到76.8%的案例。
Wise醫師表示，他的研究源自於他及共同作者Perry Pickhardt醫師與其他威斯康辛大學的夥伴的診斷放射小組的合作。Pickhardt醫師的研究是大腸癌診斷放射學這個領域中最大之一。其提出CTC可以被善用於癌症篩檢工具的觀念。我們現在的資料顯示，這個被我們稱為CTC的工具，可以讓光學大腸鏡檢查醫師信賴足以找到顯示的病灶。
【缺乏給付與訓練】
研究者認為，CTC可以幫助克服光學大腸鏡的限制因素之一。Wise醫師表示，光學大腸鏡是個有效的篩檢工具，但是它目前並未用於多數適合篩檢的族群。沒有足夠的內視鏡醫師，所以運用有限。
不過，CTC有它自己的限制因素。會議主持人、芝加哥大學醫學中心電腦斷層主任Abraham Dachman醫師解釋，CT大腸造影已經被用作篩檢工具，但是還未常規使用。缺乏廣泛使用並不是因為醫療不足，而是財務問題。Dachman醫師向Medscape Radiology表示，現在與CTC有關的最熱門議題就是給付問題。
直到2004年7月，保險公司完整給付進行虛擬大腸鏡檢查的放射科醫師。但是在2004年7月，虛擬大腸鏡被再度分類為第3類診斷碼。
Dachman醫師表示，結果，所有的保險與Medicare都停止給付虛擬大腸鏡檢查。我們一直致力於恢復給付並擴大保險範圍。
現在，多數保險公司僅在診斷目的時給付CTC，而非篩檢目的。美國癌症協會在2008年終認可虛擬大腸鏡檢查，但是給付並未隨之改變。並且到目前為止，聯邦醫療保險及醫療補助中心(CMS)仍否決給付虛擬大腸鏡檢查。不過，在美國放射學會的正面給付立場下，此抗爭仍持續進行中。2009年3月的國會聽證會聚焦在CMS懸而未決的最後決定，將於本月底宣布。
其他對於CTC整體成功限制的影響是此技術的放射訓練。在Wise醫師發表研究時，Dachman醫師在ARRS生殖泌尿道影像小組提到的主旨為，我相當關注放射師的CTC訓練以及認證。一般的放射師無法再現Pickhardt醫師等人與Wise醫師的結果。其他中心顯示可接受的或好的結果，但是它們通常未達敏感度的標準且專一度低。
最後的CMS決策會相當程度地影響使用CTC於篩檢的比率，但是應適當持續訓練。Dachman醫師表示，我認為CMS終究會改變心意，但是我認為我們必須有前瞻性，提供高品質的訓練給放射科醫師。如果你試著建立一個虛擬大腸鏡計畫，而你的放射科醫師不適任，將會喪失信度。
Wise醫師宣告沒有相關財務關係。共同作者、Pickhardt 醫師宣告與Viatronix、Medicsight、Fleet、Covidien、Philips以及VirtuoCTC有利益關係。共同作者、Kim醫師宣告與Viatronix、Medicsight以及VirtuoCTC有利益關係。Dachman 醫師擔任iCAD Inc、GE Healthcare, Inc以及ACR Image Metrix, Inc.等公司的顧問。
美國放射線醫學會(ARRS)2009年會：摘要110。發表於2009年4月27日。
ARRS 2009: Study Confirms Virtual Colonoscopy Is Reliable for Colorectal Cancer Screening
By Alice McCarthy
Medscape Medical News
May 11, 2009 (Boston, Massachusetts) — A study using computed tomography colonoscopy (CTC) found that the technique can reliably detect polyps as small as 6?mm in approximately 92% of cases. The finding was presented here at the American Roentgen Ray Society (ARRS) 2009 Annual Meeting.
In the study, conducted at the University of Wisconsin Medical School, CTC (also known as virtual colonoscopy) detected 667 (91.6%) of 739 lesions in 479 patients presenting for colorectal screening.
This study was based on an initial population of 5124 patients screened with CTC. Of this group, 639 patients (12.5% of the total) were found to have a polyp 6?mm in size or larger. Of those, 479 patients received subsequent optical colonoscopy for confirmation and polypectomy to determine positive predictive value (PPV).
"I feel that our data support the use of [CTC] as a primary screening tool for colon cancer," lead study researcher Steven Wise, MD, from the University of Wisconsin School of Medicine and Public Health in Madison, told Medscape Radiology. "We propose that it be used as an initial screening test so that the patients who do have positive CTC screening exams can then be selected out for optical colonoscopy and subsequent polypectomy."
To function as an effective screening tool, CTC must not only be sensitive for the detection of clinically relevant lesions, classified in this study as polyps 6?mm or larger, it must also demonstrate a low false-positive rate and high concordance with optical colonoscopy, he said.
The study found that the PPV of CTC did not vary according to polyp size. Approximately 92.7% of polyps 10?mm or larger were detected by CTC. The PPV for polyps 6 to 9?mm was similar, at 90.1%. However, researchers did find that polyp morphology plays a role in different PPV findings. Lesions classified as mass or carpet lesions were detected 100% of the time. However, flat lesions were identified in only 76.8% of cases.
Dr. Wise said his research stems from his association with the highly regarded diagnostic radiology team of coauthor Perry Pickhardt, MD, and others at the University of Wisconsin. "Dr. Pickhardt's body of work is one of the largest?.?.?.in the field of diagnostic radiology in colon cancer," Dr. Wise said. "Much of it contributes to this idea that CTC is going to be well-suited to serve as a screening modality for cancer. Our data here demonstrate that if we call it at [CTC], the optical colonoscopist can be confident that they will find a lesion where we said it was."
Reimbursement and Training Lacking
Study researchers suggest that CTC might help overcome 1 of the limiting factors for optical colonoscopy. "Optical colonoscopy is an effective screening tool, but it is currently not being used for the majority of the eligible screening population," Dr. Wise said. "There are not enough endoscopists, so that also limits its application."
However, CTC faces its own limiting factors. "CT colonography is used as a screening tool already, but not routinely yet," explained session moderator Abraham Dachman, MD, director of computed tomography at the University of Chicago Medical Center in Illinois. [The lack of its] widespread use is not a medical deficit but a fiscal problem. "The reimbursement issue is the hottest topic now with regard to CTC," Dr. Dachman told Medscape Radiology.
Until July 2004, insurance companies fully reimbursed radiologists for performing virtual colonoscopy. But in July 2004, virtual colonoscopy was reclassified with category?3 diagnostic codes.
"As a result of that, all insurance and Medicare stopped paying for virtual colonoscopy. We have been fighting an uphill battle ever since to reinstate and expand insurance coverage," Dr. Dachman said.
Today, most insurance companies pay for CTC only for diagnostic purposes, not for screening purposes. The American Cancer Society endorsed virtual colonoscopy in late 2008, but reimbursement has not followed suit. And thus far, the Centers for Medicaid and Medicare Services (CMS) have denied reimbursement for virtual colonoscopy. But that fight is still ongoing, with the American College of Radiology pursuing a positive reimbursement stand. Congressional hearings in March 2009 focused on the pending final decision from CMS, which will be announced later this month.
Another limiting influence on the overall success of CTC has to do with radiology training for the technique. In his keynote address at the ARRS session on genitourinary imaging, during which Dr. Wise presented his study, Dr. Dachman said: "I have significant concerns about radiologist training and certification when it comes to CTC. The average radiologist cannot usually reproduce the kind of data published by Pickhardt et al and by Dr. Wise here. Other centers show acceptable or good results, but they often do not reach that level of sensitivity and have lower specificity."
The final CMS decision will certainly influence the rate of use of CTC for screening, but the fight for optimal training will linger. Dr. Dachman said: "I think CMS will eventually change its mind, but I think we have to be proactive as radiologists to offer high-quality training to the radiologists. If you try to institute a virtual-colonoscopy program and your radiologists can't get it right, you will lose credibility."
Dr. Wise has disclosed no relevant financial relationships. Coauthor Dr. Pickhardt has disclosed financial interests with Viatronix, Medicsight, Fleet, Covidien, Philips, and VirtuoCTC. Coauthor Dr. Kim has disclosed financial interests with Viatronix, Medicsight, and VirtuoCTC. Dr. Dachman is a consultant to iCAD Inc; GE Healthcare, Inc; and ACR Image Metrix, Inc.
American Roentgen Ray Society 2009 Annual Meeting: Abstract 110. Presented April 27, 2009. |
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