Barabasch Alexandra, Kraemer Nils A, Ciritsis Alexander, Hansen Nienke L, Lierfeld Marco, Heinzel Alexander, Trautwein Christian, Neumann Ulf, Kuhl Christiane K
From the Departments of *Diagnostic and Interventional Radiology, †Nuclear Medicine, ‡Internal Medicine III, and §General, Visceral and Transplantation Surgery, University Hospital RWTH Aachen, Aachen, Germany.
Invest Radiol. 2015 Jun;50(6):409-15. doi: 10.1097/RLI.0000000000000144.
Patients with hepatic metastases who are candidates for Y90-radioembolization (Y90-RE) usually have advanced tumor stages with involvement of both liver lobes. Per current guidelines, these patients have usually undergone several cycles of potentially hepatotoxic systemic chemotherapy before Y90-RE is at all considered, requiring split (lobar) treatment sessions to reduce hepatic toxicity. Assessing response to Y90-RE early, that is, already after the first lobar session, would be helpful to avoid an ineffective and potentially hepatotoxic second lobar treatment. We investigated the accuracy with which diffusion- weighted magnetic resonance imaging (DWI-MRI) and positron emission tomography/computed tomography (PET/CT) can provide this information.
An institutional review board-approved prospective intraindividual comparison trial on 35 patients who underwent fluorodeoxyglucose PET/CT and DWI-MRI within 6 weeks before and 6 weeks after Y90-RE to treat secondary-progressive liver metastases from solid cancers (20 colorectal, 13 breast, 2 other) was performed. An increase of minimal apparent diffusion coefficient (ADCmin) or decrease of maximum standard uptake value (SUVmax) by at least 30% was regarded as positive response. Long-term clinical and imaging follow-up was used to distinguish true- from false-response classifications.
On the basis of long-term follow-up, 23 (66%) of 35 patients responded to the Y90 treatment. No significant changes of metastases size or contrast enhancement were observable on pretreatment versus posttreatment CT or magnetic resonance images.However, overall SUVmax decreased from 8.0 ± 3.9 to 5.5 ± 2.2 (P < 0.0001), and ADCmin increased from 0.53 ± 0.13 × 10(-3) mm2/s to 0.77 ± 0.26 × 10(-3) mm2/s (P < 0.0001). Pretherapeutic versus posttherapeutic changes of ADCmin and SUVmax correlated moderately (r = -0.53). In 4 of the 35 patients (11%), metastases were fluorodeoxyglucose-negative such that no response assessment was possible by PET. In 25 (71%) of the 35 patients, response classification by PET and DWI-MRI was concordant; in 6 (17%) of the 35, it was discordant. In 5 of the 6 patients with discordant classifications, follow-up confirmed diagnoses made by DWI. The positive predictive value to predict response was 22 (96%) of 23 for MRI and 15 (88%) of 17 for PET. The negative predictive value to predict absence was 11 (92%) of 12 for MRI and 10 (56%) of 18 for PET. Sensitivity for detecting response was significantly higher for MRI (96%; 22/23) than for PET (65%; 15/23) (P < 0.02).
Diffusion-weighted magnetic resonance imaging appears superior to PET/CT for early response assessment in patients with hepatic metastases of common solid tumors. It may be used in between lobar treatment sessions to guide further management of patients who undergo Y90-RE for hepatic metastases.
适合钇-90放射性栓塞（Y90-RE）治疗的肝转移患者通常处于肿瘤晚期，双侧肝叶均受累。根据现行指南，这些患者在考虑进行Y90-RE治疗之前通常已经接受了几个周期的可能具有肝毒性的全身化疗，需要分阶段（分叶）治疗以降低肝毒性。早期评估Y90-RE的疗效，即在第一次分叶治疗后就进行评估，将有助于避免无效且可能具有肝毒性的第二次分叶治疗。我们研究了扩散加权磁共振成像（DWI-MRI）和正电子发射断层扫描/计算机断层扫描（PET/CT）提供此信息的准确性。
进行了一项经机构审查委员会批准的前瞻性个体内比较试验，对35例患者进行了研究，这些患者在Y90-RE治疗实体癌（20例结直肠癌、13例乳腺癌、2例其他癌症）继发进展性肝转移之前6周内和之后6周内接受了氟脱氧葡萄糖PET/CT和DWI-MRI检查。最小表观扩散系数（ADCmin）增加或最大标准摄取值（SUVmax）降低至少30%被视为阳性反应。通过长期临床和影像学随访来区分真反应和假反应分类。
基于长期随访，35例患者中有23例（66%）对Y90治疗有反应。在治疗前与治疗后的CT或磁共振图像上未观察到转移灶大小或对比增强有明显变化。然而，总体SUVmax从8.0±3.9降至5.5±2.2（P<0.0001），ADCmin从0.53±0.13×10⁻³mm²/s增加至0.77±0.26×10⁻³mm²/s（P<0.0001）。治疗前与治疗后ADCmin和SUVmax的变化呈中度相关（r=-0.53）。35例患者中有4例（11%）转移灶为氟脱氧葡萄糖阴性，因此无法通过PET进行反应评估。35例患者中有25例（71%）PET和DWI-MRI的反应分类一致；35例中有6例（17%）不一致。在6例分类不一致的患者中有5例，随访证实了DWI做出的诊断。预测反应的阳性预测值，MRI为23例中的22例（96%），PET为17例中的15例（88%）。预测无反应的阴性预测值，MRI为12例中的11例（92%），PET为18例中的10例（56%）。检测反应的敏感性MRI（96%；22/23）显著高于PET（65%；15/23）（P<0.02）。
对于常见实体瘤肝转移患者的早期反应评估，扩散加权磁共振成像似乎优于PET/CT。它可用于分叶治疗期间，以指导接受Y90-RE治疗肝转移的患者的进一步管理。
