Colorectal Cancer Liver Metastases — RadCall Procedure Guide

1

Indications & Patient Selection

CRC mets, ablation vs IAT criteria, contraindications, workup

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Indications — Ablation

CRC is the #1 indication for liver-directed therapy in the US — ~50% of CRC patients develop liver metastases
Lesions ≤3–4 cm, ≤5 lesions, ≥1 cm from bile ducts and major vessels
Curative intent possible for oligometastatic disease
Fit for anesthesia (General or MAC); Child-Pugh A/B
Simultaneous 2-probe technique for 2–4 cm lesions (15 mm apart)

Indications — Intra-arterial Therapy (IAT)

Unresectable disease or chemo-refractory liver-dominant CRC
≤75% liver replacement by tumor
Options: TACE (DEBs or DEBIRI), TARE (Y-90), HAI pump (hepatic arterial infusion)
Multi-disciplinary discussion required: IR + colorectal surgery + oncology
DEBIRI (irinotecan-eluting beads) preferred agent for CRC TACE — matches CRC chemosensitivity

Contraindications

Ablation: lesion >4 cm near major bile duct, Child-Pugh C, central portal vein thrombosis, >5 lesions
IAT: >75% liver replacement, hepatic decompensation (bilirubin >2×ULN), uncorrectable coagulopathy
Uncorrectable coagulopathy (INR >1.5, platelets <50K)
Active GI bleeding or bowel obstruction
Lung shunt fraction >20% (Y-90 absolute contraindication)

Pre-procedure Workup

CT chest/abdomen/pelvis (staging — rule out extrahepatic disease)
MRI liver with contrast (lesion count, characterization, margin assessment)
CEA level (baseline; trend post-treatment)
Colonoscopy (rule out synchronous primary or local recurrence)
LFTs, bilirubin, coagulation panel (PT/INR, platelets)
MDT discussion documented before proceeding

2

Pre-Procedure Checklist

Equipment, medications, consent points — ablation and IAT

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Ablation Setup

MWA probe: Neuwave 17G or Covidien HS System
2–3 probes available for overlapping ablation of 3–4 cm lesions
CT or US guidance system; US fusion capability if available
D5W for hydrodissection (50–100 mL) — lesions near diaphragm or bowel
General anesthesia or MAC (coordinate with anesthesia in advance)
Laparoscopic access available for difficult-to-reach lesions

IAT / Angiography Setup

Standard angiography suite (biplane preferred for hepatic work)
Diagnostic hepatic arteriogram supplies (5 Fr sheath, Cobra/SH catheter)
2.4 Fr or 2.7 Fr microcatheter for superselective access
CBCT (cone-beam CT) capability — essential for CRC (hypovascular tumors)
DEBIRI beads 100–300 µm (preferred) or doxorubicin DEBs as alternative
Y-90: Tc-99m MAA for pre-treatment mapping arteriogram
Blood bank availability; liver function trend monitoring

MRI liver reviewed. Lesion count confirmed, target lesions characterized, margins from bile ducts and major vessels measured (≥1 cm required for ablation).

Coagulopathy corrected. INR ≤1.5, platelets ≥50K before any hepatic procedure.

MDT sign-off documented. IR + colorectal surgery + oncology consensus recorded in chart.

Antibiotics ordered. Routine: cefazolin 1–2 g IV pre-procedure. Post-Whipple: cefazolin + metronidazole (Flagyl); consider IV ertapenem 1 g for 24h post-procedure.

Hydrodissection supplies confirmed (D5W, 18G needle, syringe) for lesions near diaphragm or bowel.

Y-90 MAA mapping done (if Y-90 planned): lung shunt fraction <20% confirmed; dose calculated via BSA method (SIR-Spheres) or partition model (TheraSphere).

Consent obtained. Key risks discussed: bile duct injury, hepatic abscess (esp. post-Whipple), RILD (Y-90), post-embolization syndrome, need for repeat procedures.

3

Relevant Anatomy

Couinaud segments, hepatic arteries, bile ducts, portal vein

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Liver Segment Anatomy (Couinaud)

Segments I–VIII (Couinaud classification): critical for surgical resection planning vs ablation targeting
Right lobe: segments V, VI, VII, VIII; left lobe: II, III, IV; caudate: I
Segment IV (quadrate lobe): between middle hepatic vein and falciform ligament; served by left hepatic artery segment IV branches — important for selective TACE
Segment VI/VII: near IVC → heat sink effect during ablation; may require higher power/longer ablation time

Hepatic Arterial Anatomy

Replaced/accessory hepatic artery variants common (20–25%) — always verify before IAT
Right hepatic artery (RPHA): most commonly from proper hepatic artery; replaced right: from SMA (~15%)
Left hepatic artery (LPHA): standard from proper; replaced left: from left gastric artery (~10%)
Segment IV branches: from left hepatic artery (not right) — must identify to avoid non-target embolization to left lobe during right lobe TACE
Cystic artery origin: from RPHA — identify to avoid cholecystitis during embolization

Bile Ducts & Thermal Ablation Safety

Lesion within 1 cm of bile duct = high risk of bile duct injury with thermal ablation (RFA/MWA)
Right and left hepatic ducts: confluence at hepatic hilum — avoid ablation near hilum
Biliary cooling via ERCP balloon inflation can protect duct during hilar ablation (if available)
Biloma formation (bile duct leak → cystic collection): manage with percutaneous drainage if symptomatic

Portal Vein & IVC

Portal vein: right PV (segments V–VIII) and left PV (segments II–IV)
Tumor thrombus in main PV: contraindication to TACE (hepatic ischemia risk); consider Y-90 (radiation tolerates partial flow)
IVC: segments VI/VII lesions adjacent to IVC → heat sink effect dissipates ablation zone; plan for extended ablation time or cryo
Hepatic veins (right, middle, left): 5 mm proximity = heat sink; tumor touching hepatic vein = positive margin risk with ablation

4

Step-by-Step Technique

MWA ablation, DEBIRI-TACE, Y-90 radioembolization, comparison table

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A. CT/US-Guided Liver Ablation (MWA)

1

Positioning & Pre-procedure Planning

Patient supine on CT table. Obtain planning CT scan; co-register with pre-procedure MRI (lesion characterization and margin assessment). Confirm lesion visibility on CT — if poorly visible, plan US fusion guidance. Identify nearest bile duct, hepatic vein, and bowel proximity for all target lesions.

2

Hydrodissection (if Required)

For lesions near diaphragm or bowel: inject D5W 50–100 mL via 18G needle into the peritoneal space between lesion and at-risk structure. Confirm adequate separation (≥1 cm) on CT before probe placement. D5W preferred over normal saline (electrically non-conductive; does not interfere with MWA field).

3

MWA Probe Placement

Advance 17G MWA probe (Neuwave or Covidien HS) to center of target lesion under CT guidance. For 2–4 cm lesions: simultaneous dual-probe technique with probes placed 15 mm apart for adequate overlapping ablation zone. Confirm probe tip position in all three planes on CT before firing.

4

MWA Firing

Single probe (<2 cm lesion): 65W × 10 minutes. Dual-probe (2–4 cm): simultaneous firing per system protocol; typical setting 65W × 12–15 minutes with overlapping zones. Monitor for probe position stability during ablation (patient breathing; use breath-hold or ventilator apnea if under GA).

5

Post-ablation Assessment

Obtain CT after ablation: look for low-density ablation zone (CT) or hyperechoic zone (US). Confirm 1-cm margin in all directions beyond visible tumor. If margin appears <1 cm, perform second overlapping ablation before probe removal. Remove probe with tract ablation if indicated (hepatocellular approach).

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Post-ablation CT & Recovery

Final CT to confirm adequate zone and rule out immediate complications (perihepatic hematoma, pneumothorax). Patient recovers under monitored anesthesia care. Discharge same-day (if outpatient procedure) or admit overnight for pain management. MRI liver at 4–6 weeks for first surveillance imaging.

B. TACE for Unresectable CRC Liver Mets (DEBIRI Preferred)

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Diagnostic Hepatic Arteriogram

Access via right common femoral artery (CFA) with 5 Fr sheath. Flush aortogram or selective SMA injection first to identify replaced/accessory hepatic arteries. Celiac arteriogram: identify proper hepatic artery, RHA, LHA, GDA, cystic artery, and segment IV branches. Note any arterial variants before proceeding.

2

CBCT for Tumor Targeting

CBCT is mandatory for CRC — CRC liver mets are hypo- to isovascular on DSA and are frequently invisible on standard fluoroscopy. Perform CBCT with contrast injection to identify tumor enhancement and feeding vessels. Use CBCT roadmap to guide superselective catheterization to tumor-bearing segments.

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Superselective Catheterization

Advance 2.4 Fr microcatheter coaxially to the tumor-feeding segmental or subsegmental vessel. Position beyond GDA and cystic artery origin to avoid non-target embolization. Confirm catheter tip position with CBCT or DSA. For bilobar disease: treat dominant lobe first; contralateral lobe treated at separate session 4–6 weeks later.

4

DEBIRI Injection

Inject irinotecan drug-eluting beads (DEBIRI) 100–300 µm slowly under fluoroscopic guidance. Slow injection to stasis; do NOT over-embolize to complete stasis of main hepatic artery. Monitor for reflux. If doxorubicin DEBs used instead (off-label for CRC): same technique, 100–300 µm. Confirm stasis and adequate distribution.

5

Post-TACE Assessment & Admission

Final angiogram to confirm stasis. Remove access; manual compression or closure device. Admit overnight for post-embolization syndrome management: IV fluids, ondansetron, IV ketorolac or opioid PRN, antiemetics. Discharge next day if tolerating PO. Repeat treatment of contralateral lobe at 4–6 weeks if bilobar disease.

C. Y-90 Radioembolization (Glass or Resin Microspheres)

1

Pre-treatment MAA Mapping Arteriogram

Perform diagnostic hepatic arteriogram; plan treatment position. Inject Tc-99m MAA (macroaggregated albumin) via microcatheter at planned treatment position. Nuclear medicine lung scintigraphy immediately after: calculate lung shunt fraction (LSF). LSF <10% = ideal; 10–20% = proceed with dose reduction; >20% = contraindicated (radiation pneumonitis risk).

2

Dose Calculation

Resin SIR-Spheres: BSA (body surface area) method — dose (GBq) = [BSA − 0.2] + (liver tumor volume / total liver volume). Glass TheraSphere: partition model — prescribe target dose to tumor 80–150 Gy; calculate activity based on tumor and normal liver volumes. Adjust for LSF. Radiation safety physicist involvement required for dose calculation.

3

Y-90 Delivery

Treatment performed 1–2 weeks after MAA mapping. Microcatheter positioned at same location as MAA mapping. Inject Y-90 microspheres slowly per manufacturer protocol (radiation safety team present in suite). Avoid reflux. Post-injection bremsstrahlung scan (or PET/CT for glass microspheres) immediately after to confirm distribution within targeted hepatic segments.

4

Post-procedure & Radiation Precautions

Discharge same-day in most cases (Y-90 is outpatient). Radiation safety instructions given to patient (contact precautions, pregnancy avoidance). LFT and bilirubin check at 1 month (RILD surveillance). Imaging (CT or MRI) at 3 months for response assessment. CEA trend monitored alongside imaging.

Treatment Comparison: Ablation vs TACE vs Y-90 vs HAI Pump for CRC Liver Mets

Feature	Ablation (MWA/RFA)	DEBIRI-TACE	Y-90 (TARE)	HAI Pump
Best lesion size	≤3–4 cm	Any (multi-focal)	Any (diffuse)	Any (diffuse)
Lesion count	≤5	Multi-focal OK	Multi-focal OK	Multi-focal OK
Curative potential	Yes (oligomets)	No (palliative)	Rare	No (palliative)
Vascularity needed	No	Less critical (CBCT)	No	No
Key agent	Heat	Irinotecan (DEBIRI)	Y-90 microspheres	FUDR (floxuridine)
Portal vein thrombus	OK if peripheral	Contraindicated	Relative CI	No direct effect
Key complication	Bile duct injury	Post-embolization syndrome	RILD	Biliary sclerosis
Evidence	Gillams et al 2013	PRECISION V (DEBIRI)	SIRFLOX/FOXFIRE/EPOCH	Kemeny et al NEJM 1999

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5

Fluoroscopy / CT Landmarks

Tumor blush, CBCT, ablation zone adequacy

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Angiographic Appearance of CRC Mets

CRC liver mets are characteristically hypo- to isovascular on DSA — tumor blush may be absent or subtle on standard DSA fluoroscopy
CBCT is essential for CRC TACE: cone-beam CT with contrast injection shows tumor enhancement and feeding vessel anatomy not visible on DSA alone
CBCT technique: inject 2–3 mL/s dilute contrast via microcatheter; acquire CBCT during late arterial phase; overlay with pre-procedural MRI for fusion guidance
Capillary blush on CBCT: subtle enhancement in tumor vs adjacent liver parenchyma — use window/level optimization to highlight

Ablation Zone Adequacy on CT

Target: 1-cm circumferential margin of ground-glass opacity (GGO) or low-density halo beyond visible tumor edge on post-ablation CT
Check ablation zone in all three planes: axial, coronal, sagittal — lesions near dome of liver may appear adequate on axial but have inadequate superior margin
Low-density zone on CT correlates with thermally damaged tissue; confirm margins before removing probe
US appearance: hyperechoic ablation zone (gas bubbles) — overestimates true ablation zone; CT is more reliable for margin assessment
Heat sink effect (near large vessels/IVC): ablation zone may appear asymmetric with narrowing adjacent to vessel — consider probe repositioning or second ablation

Portal Venous Phase CT — Lesion Detection

CRC liver mets are best visualized on portal venous phase CT (60–70 sec delay) as hypodense lesions relative to enhancing background liver parenchyma. On MRI, diffusion-weighted imaging (DWI) and hepatobiliary phase (HBP) are most sensitive for lesion detection and margin assessment. Co-registering pre-procedure MRI with intraprocedural CT/US improves targeting accuracy for lesions poorly visible on CT guidance alone.

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Troubleshooting

Intraoperative problems and solutions

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Invisible Lesion

Lesion Not Visible on CT Guidance

Use real-time US fusion guidance (pre-procedure MRI or CT overlay registered to live US). Cone-beam CT with contrast via a previously placed angiographic catheter can make lesions visible. Intraoperative US (laparoscopic or open) considered if other modalities fail. Ensure patient adequately hydrated (IV contrast enhancement improves lesion conspicuity on intraprocedural CT).

Inadequate Margin Near Bile Duct

Ablation Margin Insufficient Due to Proximity to Bile Duct (<1 cm)

Adjust probe angle to maximize distance between ablation zone margin and bile duct; do not simply increase power (increases duct injury risk). Biliary cooling: advance balloon catheter into biliary system via ERCP with continuous cold saline irrigation during ablation. Consider alternative therapy (Y-90 or TACE) for lesions abutting central bile ducts. Document planned approach before probe placement.

Poor Tumor Blush (TACE)

Hypovascular CRC — No Visible Blush on DSA

Perform CBCT with contrast to identify enhancement not visible on DSA (mandatory step for CRC). If CBCT confirms viable tumor, proceed with superselective DEBIRI embolization based on CBCT roadmap. If tumor truly hypovascular and no CBCT enhancement: consider Y-90 (radioembolization is particle-based and does not require hypervascularity for efficacy). Discuss with MDT.

Non-target Embolization

GDA or Cystic Artery at Risk During TACE

Always identify the GDA before embolization — GDA reflux with DEB particles → duodenal ischemia and gastroparesis. Position microcatheter beyond GDA origin. Identify cystic artery (from RPHA) and ensure catheter tip is distal to its origin before injecting DEBIRI to right lobe. If adequate selectivity cannot be achieved, stop and reassess; do not force injection.

Lung Shunt >20% (Y-90)

Excessive Hepatopulmonary Shunting on MAA Mapping

LSF >20% is absolute contraindication for Y-90 (radiation pneumonitis). Consider: (1) coil embolization of hepatic artery to redirect flow prior to repeat mapping; (2) fractionated dosing over multiple sessions; (3) switch to TACE or HAI pump as alternative. Recheck LSF after coil embolization if attempted. Document and discuss with patient before proceeding with any modification.

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Complications

Ablation, TACE, Y-90 specific complications and management

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Ablation Complications

Bile duct injury (stricture / leak) — most common serious complication; occurs when lesion <1 cm from bile duct; presents as biloma or biliary stricture weeks post-procedure; manage with ERCP stenting or percutaneous biliary drainage
Hepatic abscess (1–3%) — especially in post-Whipple patients (biliary-enteric anastomosis = contaminated biliary system); prophylactic antibiotics mandatory; IV ertapenem 24h post-procedure
Perihepatic hematoma — usually self-limited; monitor with CT
Pneumothorax (dome lesions) — rare; managed conservatively or with chest tube
Tumor seeding along probe tract — rare; use coaxial technique to minimize

IAT Complications (TACE / Y-90)

Post-embolization syndrome — fever, nausea, right upper quadrant pain 1–3 days after TACE; expected; supportive care; admit overnight; NSAIDs + ondansetron + IV fluids
Radiation-induced liver disease (RILD) — Y-90 complication; bilirubin >3× baseline at 1 month; anicteric RILD (ascites, elevated LFTs without jaundice); avoid Y-90 if marginal liver function (bilirubin >2 mg/dL baseline)
Biloma — bile duct injury from non-target embolization or ablation; percutaneous drainage if symptomatic; ERCP stenting if biliary leak
Cholecystitis (TACE) — non-target embolization of cystic artery; prophylactic cholecystectomy not standard; manage medically; rarely requires cholecystectomy
Radiation pneumonitis (Y-90, LSF >20%) — prevented by pre-treatment mapping

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Critical Pearls

High-yield clinical guidance for CRC liver-directed therapy

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❖

Plan the 1-cm ablative margin before placing the probe. The 1-cm margin is the standard for local tumor control — negative ablative margins are oncologically equivalent to surgical resection for local recurrence-free survival. Map the planned ablation zone on pre-procedure CT/MRI and confirm the planned probe trajectory achieves this margin in all planes before committing to probe placement.

❖

Post-Whipple patients require prophylactic antibiotics before ANY liver procedure. Biliary-enteric anastomosis creates a permanently contaminated biliary system. Cefazolin + metronidazole (Flagyl) pre-procedure is the minimum; consider IV ertapenem 1 g for 24h post-procedure for ablation in Whipple patients. Hepatic abscess in this population can be life-threatening and is largely preventable with aggressive antibiotic prophylaxis.

❖

CBCT is not optional for CRC TACE — it is the procedure. CRC liver mets are characteristically hypovascular; standard DSA fluoroscopy will not show the tumor. Cone-beam CT with contrast injection at the planned treatment position identifies tumor enhancement, feeding vessels, and non-target anatomy. Skip CBCT and you are embolizing blindly in most CRC cases.

❖

DEBIRI > conventional TACE for CRC. Irinotecan-eluting beads provide superior local drug delivery that matches CRC chemosensitivity (CRC is an irinotecan-responsive tumor; doxorubicin is NOT first-line for CRC). The PRECISION V trial and subsequent data support DEBIRI for improved response rates and tolerability. Use DEBIRI 100–300 µm as the default agent when performing TACE for CRC liver mets.

❖

Ablation + resection is additive — think combinatorial. For patients with bilobar disease where complete resection would require an excessively large liver resection: limited resection of dominant/large lesions + MWA of smaller contralateral lesions maximizes oncologic clearance while preserving functional liver volume. This combined approach can convert an unresectable patient to R0 status. Discuss at MDT before each case.

✶

COLLISION Trial (Lancet Oncol 2024): Landmark RCT (n=308) demonstrating non-inferiority of thermal ablation vs resection for resectable colorectal liver metastases ≤3 cm (3-year OS 79.6% ablation vs 84.5% resection). Ablation had significantly fewer complications and shorter hospital stay. This is practice-changing: ablation is now a first-line option (not backup) for tumors ≤3 cm in appropriate patients with favorable location. Does not apply to tumors adjacent to major bile ducts or vessels.

❖

Y-90 for chemo-refractory unresectable CRC: use SIRFLOX/FOXFIRE/EPOCH data. Y-90 + FOLFOX vs FOLFOX alone (SIRFLOX trial): Y-90 significantly improves hepatic progression-free survival. The EPOCH pooled analysis confirmed benefit in hepatic PFS. Y-90 is a validated option for chemo-refractory CRC liver-dominant disease. Reference these trials when advocating for Y-90 in multidisciplinary tumor boards.

9

References & Resources

Primary sources and related procedures

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Key Trials & Data

PRECISION V: DEBIRI vs conventional TACE — DEBIRI superior response, tolerability in CRC liver mets
SIRFLOX (Van Hazel et al): Y-90 + FOLFOX vs FOLFOX alone — improved hepatic PFS
FOXFIRE / EPOCH pooled analysis: Y-90 benefit in hepatic progression-free survival confirmed
Gillams et al, Ann Oncol 2013: Ablation outcomes in CRC liver mets — survival benefit with curative ablation

Primary References

Faintuch S, Salazar G, eds. Interventional Radiology Procedures in Biopsy and Drainage. Thieme; 2016. Ch. 7: Ahmed M. Liver Tumor Ablation. Ch. 8: Narayanan G, Mohan PP. Intra-arterial Therapies for Liver Tumors.
Gillams A, Khan Z, Osborn P, Lees W. Survival after radiofrequency ablation in 494 patients with multiple inoperable colorectal liver metastases. Ann Oncol. 2013;24(5):1274–1280.
Fiorentini G, Aliberti C, Tilli M, et al. Intra-arterial infusion of irinotecan-loaded drug-eluting beads (DEBIRI) versus intravenous therapy (FOLFIRI) for hepatic metastases from colorectal cancer: final results of a phase III study. Anticancer Res. 2012;32(4):1387–1395.
Van Hazel GA, Pavlakis N, Goldstein D, et al. Treatment of fluorouracil-refractory patients with liver metastases from colorectal cancer by using yttrium-90 resin microspheres plus concomitant systemic oxaliplatin, fluorouracil, and leucovorin chemotherapy. J Clin Oncol. 2009;27(25):4089–4095.
Wasan HS, Gibbs P, Sharma NK, et al. (FOXFIRE, SIRFLOX, FOXFIRE-Global investigators). First-line selective internal radiotherapy plus chemotherapy versus chemotherapy alone in patients with liver metastases from colorectal cancer (FOXFIRE, SIRFLOX, and FOXFIRE-Global): a combined analysis of three multicentre, randomised, phase 3 trials. Lancet Oncol. 2017;18(9):1159–1171.
Kemeny N, Huang Y, Cohen AM, et al. Hepatic arterial infusion of chemotherapy after resection of hepatic metastases from colorectal cancer. N Engl J Med. 1999;341(27):2039–2048.
van der Reijd DJ, et al. (COLLISION Trial). Resection versus local ablation of colorectal liver metastases (COLLISION): a phase 3 prospective, multi-institutional, open-label, randomised controlled trial. Lancet Oncol. 2024;25(12):1562–1572. DOI: 10.1016/S1470-2045(24)00660-0 — RCT of resection vs thermal ablation (MWA/RFA) for resectable colorectal liver metastases ≤3 cm. Ablation was non-inferior to resection for overall survival (3-year OS: 79.6% vs 84.5%, non-inferiority met). Ablation had significantly fewer complications. Supports ablation as a primary treatment option (not just for unresectable disease) for tumors ≤3 cm in appropriate patients.