Key points
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Standardized follow-up after an oncologic intervention is needed to improve the quality of care.
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MRI, CT, and PET-CT are the main modalities.
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PET-CT is most valuable in lung cancer and colorectal liver metastases.
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RECIST 1.1 is suboptimal for follow-up after oncologic intervention.
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Research on adequate response evaluation methods is needed.
Background
Methods
Topic | Disease | Intervention | Modalities | Hits | Articles included |
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Thermal ablation in CRLM | Colorectal liver metastasis | Thermal ablation techniques: radiofrequency, microwave | CT, MRI, FDG-PET(-CT), CE-US | 497 | 14 |
TARE in liver cancer | Liver metastasis, intrahepatic cholangiocarcinoma, hepatocellular carcinoma | Transarterial radioembolisation (Yttrium90/TARE/SIRT) | CT, MRI, FDG-PET(-CT), Y90 SPECT/CT/PET | 128 | 12 |
TACE in HCC | Hepatocellular carcinoma | Transarterial chemoembolization | CT, MRI, FDG-PET(-CT), CE-US | 417 | 69 |
Thermal ablation in RCC | Renal cell carcinoma | Thermal ablation techniques: cryoablation, radiofrequency, microwave | CT, MRI | 518 | 39 |
Thermal ablation in NSCLC | Non-small cell lung cancer | Thermal ablation techniques: radiofrequency, microwave | CT, MRI, FDG-PET(-CT) | 181 | 21 |
Exclusion criteria all topics | Case reports, meta-analysis, reviews, other locoregional therapies, other language than English, mixed cohort studies where data on specific disease separately was not derivable. | ||||
Purpose in all topics | Evaluation of accuracy or efficacy of imaging modalities to detect local tumor progression or tumor recurrence. |
Results
Kidney | Liver | Lung | |
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Follow-up schedule | First year: 1, 3, 6 , 12 months Thereafter: every 12 months (chest imaging every 12 months) | First year: 1, 3, 6, 9, 12 months Thereafter: every 6 months Consider shortening of interval in high risk patients or other signs of recurrence | First year: 1, 3, 6, 9, 12 months (optional: before discharge after ablation) Thereafter: every 6 months |
Recommended modalities | 1. CT or MRI of the kidneys 2. Biopsy only after 6 months in case of suspected recurrence | 1. Primary MRI (mandatory after TACE with Lipiodol), secondary CT 2. PET-CT only for metastases > 2cm and not for HCC 3. PET-CT (if available) within 48h after ablation 4. PET-CT as a problem solver and in case of suspected LTP 5. Biopsy of ablation margin can be considered in margins < 5mm (➔optional to replace MRI at 6 and 12 months by PET-CT) | 1. CT 2. PET-CT not before 6 months, only in case of suspected recurrence (and targeted biopsy for recurrence), whole-body evaluation |
Computed tomography | unenhanced | unenhanced (HCC) | unenhanced CT optional to establish enhancement compared to baseline late arterial (35s) after treatment |
arterial phase (20-30s) | late arterial (35-40s) (HCC) | ||
nephrogenic phase (100s) | portal-venous (70s) (CRLM+HCC) | venous (70s) optional, if available | |
delayed phase (10 min; to assess complications) | late venous (≥120s) (HCC) | ||
slice thickness maximally 3 mm | slice thickness maximally 3 mm | slice thickness 1 mm | |
Magnetic resonance imaging | axial T2W (with and without fatsat) | axial GRE in and opposed phase T1W | |
axial and coronal dual echo | axial T2W FSE (with and without fatsat | ||
axial dynamic 3D GRE before and after Gd (20/70/180s) | axial dynamic 3D fatsat GRE before and after Gd (20/70/180s) | ||
axial 5 min post contrast GRE | axial 20 min after hepatobiliary specific Gd agent | ||
axial DWI | axial DWI | ||
subtraction images are highly recommended for HCC | |||
axial and coronal T2 HASTE | |||
PET-CT | NA | Only in CRLM: standard protocol for FDG-PET-CT | standard protocol for FDG-PET-CT |
Thermal ablation for CRLM | TARE for CRLM | TACE&TARE for HCC | Thermal ablation for renal cancer | Thermal ablation for lung cancer | |
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CT | * increase of ablation zone size * small size difference between metastasis and ablation zone * ablation rim discontinuity or irregular shape | * Choi outperforms RECIST 1.1 for response assessment * arterial perfusion has potential to assess response (reduction in arterial perfusion predicts outcome in liver mets, not HCC) | * residual arterial enhancement (thick, nodular or irregular ring, especially with wash-out) | * early peripheral enhancing rim that sustains after 3 months * focal or nodular enhancement at ablation margin (enhanced > 15 HU at CT * increase in scar volume after 2 months post-ablation | * increase in size of the ablation scar * appearance of nodular, irregular, eccentric solid component in or at the margin of ablation zone * new contrast enhancement > 15 HU |
MRI | * increase of ablation zone size * small size difference between metastasis and ablation zon same as on CT * T2 moderate high signal (focal, eccentric or nodular) at the margin * persistent high signal intensity on high b-value DWI and low ADC * disruption of the interface between ablation zone and liver parenchyma * T1 hyperintensity > 9 months * thickened or irregular peri-ablation zone tissue rim (low T1 & high T2) | * DWI at 4 weeks can predict outcome and potentially can outperform PET-CT * caveat false positives due to inflammation | * same as for CT * DWI and DCE seem promising | * same criteria as for CT * enhancement: >15% increase in signal intensity on MRI is significant) * after cryoablation: interrupted T2 low intensity rim | NA |
PET-CT | * focal, eccentric or rim shaped FDG-uptake after 4-6 months post-ablation | * reduction of ≥50% in SUVmax (FDG-PET-CT) at 4 weeks predicts outcome | NA | NA | * new FDG uptake in the scar > 6 months after ablation |
A. Liver cancer: thermal ablation of CRLM, TARE of CRLM, and intra-arterial therapy (TACE and TARE) of HCC
1. Follow-up after thermal ablation for colorectal liver metastases: RFA and MWA
Computed tomography
FDG-PET-CT
MRI
Ultrasound
Ablation zone biopsy
Recommendations
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MRI and PET-CT are the primary recommended modalities, CT is the secondary recommended modality
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MRI and PET-CT seem to be comparable in accuracy to detect local tumor progression, depending on the time point of follow-up
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PET-CT is superior to CT during follow-up after thermal ablation (RFA/MWA) to detect local tumor progression
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PET-CT seems most useful to detect local tumor progression shortly after ablation (24–48 h) or after 4 months
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PET-CT is only indicated for metastases > 2 cm
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MRI might suffice with PET-CT as a problem solver or in case of suspected recurrence > 6 months (mostly based on expert opinion)
2. Follow-up after TARE for CRLM
FDG-PET-CT
Computed tomography
MRI
Radiation-induced changes in the liver due to TARE
Conclusion
Recommendations
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FDG-PET-CT is recommended to assess early response 4 weeks after TARE in CRLM
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Size-based criteria using RECIST 1.1 are not reliable for follow-up of patients, while ceCT with the use of Choi criteria might be a suitable alternative
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Early contrast-enhancement on MRI is usually caused by inflammation and diffusion-weighted imaging can help distinguish inflammation from tumor
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Arterial perfusion on ceCT has the potential to assess response, but new studies need to confirm these findings
3. Follow-up after TACE or TARE for HCC
Computed tomography
MRI
FDG-PET-CT
Ultrasound
Recommendations
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MRI is the recommended follow-up modality; CT is the next best modality
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MRI is mandatory when conventional TACE with lipiodol has been performed, multiphasic CT can be performed to assess lipiodol distribution
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CT protocol should include a quadruple-phase CT protocol including unenhanced images
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There is no (established) role for PET-CT or (contrast-enhanced) ultrasound in follow-up
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During follow-up, modified RECIST or EASL criteria should be the basis to identify recurrence
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Sufficient evidence is lacking on new techniques such as DWI/DCE-MRI and perfusion CT but these techniques seem promising
4. Follow-up schedules after locoregional treatment of the liver
Recommendations for follow-up schedule (Table 2):
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Imaging at 1, 3, 6, 9, 12 months in the first year and every 6 months in the subsequent years
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In patients with a high risk for recurrence (ex. infiltrative type, irregular necrosis after TACE, or poor lipiodol deposition after cTACE), some evidence exists to shorten follow-up intervals in the first year in HCC
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In case of other indications for a recurrence (e.g. increasing CEA in CRLM or equivocal findings on imaging), an additional follow-up moment can be scheduled
B. Follow-up after thermal ablation for renal cancer
Recommendations
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Follow-up imaging at 1 month after ablation to assess for complications and set baseline for future follow up by CT or MRI
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If there is a concern for incomplete treatment at 1 month, a 3-month follow-up is recommended to evaluate the need and prepare for a second treatment
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If complete treatment was performed, follow-up is recommended at 6 and 12 months
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Annual contrast-enhanced CT or MR are suggested up to 5 years
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If concern for recurrence, consider biopsy to confirm
C. Follow-up after thermal ablation of lung tumors
Computed tomography
FDG-PET-CT
MRI
Recommendations
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Contrast-enhanced CT is the preferred modality
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PET-CT is recommended > 6 months after ablation, due to the high rate of false-positive results before 6 months
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PET-CT should be used when local progression is suspected at CT, when the whole-body evaluation is required, or to precisely target a suspected recurrence for biopsy.
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A contrast-enhanced CT is recommended before discharge of the patient to provide baseline measurements of the ablation zone and detect early complications
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A contrast-enhanced CT 1 month after ablation is recommended as baseline for further follow-up
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After 1 month, the ablation zone is expected to remain homogeneous without any significant enhancement, with gradual decrease in size and regular margins.
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After 6 months, the treated lesion may remain stable or slightly decrease in size after RFA or MWA. Shrinkage after cryoablation is usually more profound.
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Dual-energy CT, perfusion CT, and thoracic MR will possibly play a role in patient’s surveillance after lung ablation, but are still under investigation.