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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3645_Библиотеки_им_академика_М_И_Перельмана
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Case 20 Placement of Fiducial Markers to Facilitate Image-Guided
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Radiation Therapy
Figure 20.3
Figure 20.4
Figure 20.5
Findings
Figure 20.6
▶ Asingle image from a contrast-enhanced computed tomography (CT) scan shows a 6cm viable tumor at the
dome of the liver (Fig.20.3, arrows). Posteriorly (arrowhead) is an area of treated tumor that had been stable
for 18months.
▶ Noncontrast CT at the time of ducial marker placement (Fig.20.4) shows two gold ducial markers
(arrowheads), one at the anterior medial border of the tumor and a second at the lateral aspect of the tumor.
Aneedle is seen targeting a third location within the tumor for placement of an additional ducial markers.
▶ Anteroposterior and lateral scout images from the treatment-planning CT (Figs. 20.5 and 20.6) show
placement of four ducial markers in multiple superior/inferior and anterior/posterior positions relative to
the tumor. Coils are present lower in the liver (arrowhead) from prior embolization of an arterio-portal shunt
seen during a therapeutic embolization.
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Teaching Points
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▶ Image-guided radiation therapy (IGRT) is performed using orthogonal imaging to visualize opaque ducial
markers to provide precise targeting of the tumor during the entire treatment. is is most commonly
indicated in areas susceptible to respiratory motion, including the lung and upper abdominal viscera.
▶ Fiducial markers placed within necrotic parts of tumors are prone to migrating within the tumor. is has also
been an issue with ducial markers placed in small lung lesions.
▶ Optimal placement involves placement of at least three markers in dierent planes within the tumor as seen
on orthogonal imaging.
Management
▶ Fiducial markers can be made from gold or platinum. ey are typically submillimeter in diameter and can be
placed coaxially through an 18- or 19-gauge needle.
▶ As an alternative in lung, coils may be placed to minimize the risk of migration of markers out of the
parenchyma and into the pleural space.
▶ When indicated, core biopsy can be performed through the access needle prior to ducial implantation.
Further Reading
Kothary N, Dieterich S, Louie JD, etal. Percutaneous implantation of ducial markers for imaging-guided radiation therapy.
Am J Roentgenol. 2009; 192:1090–1096.
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History
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▶ Hepatocellular Carcinoma in a Patient with Nonalcoholic Steatohepatitis
Case 21
Figure 21.1
Figure 21.3
Figure 21.2
Figure 21.4
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Case 21 Hepatocellular Carcinoma Treated with Microwave Ablation
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Figure 21.5
Figure 21.6
Figure 21.7 Figure 21.8
Findings
▶ Arterial phase contrast-enhanced computed tomography (CT) shows a hypervascular lesion in a cirrhotic
liver (Fig. 21.5). e lesion contains macroscopic fat (arrow), a nding common to hepatocellular carcinoma
(HCC) and hepatic adenomata.
▶ Angiography immediately prior to embolization shows the hypervascular tumor corresponding to the ndings
on CT (Fig.21.6) Postembolization noncontrast CT (Fig. 21.7) shows contrast retention in the majority of the
tumor with a defect in the anterior margin (arrow).
▶ Amicrowave electrode is seen in the anterior margin of the tumor targeting the area that was suboptimally
treated by embolization (Fig.21.8).
Teaching Points
▶ In a patient with risk factor(s) for HCC, early arterial enhancement with portal venous phase washout in a
lesion >1–2cm is diagnostic of HCC. is is one of few malignancies that may be diagnosed with imaging
alone (i.e., does not require tissue conrmation).
▶ Patients with cirrhosis may not be candidates for surgery due to liver dysfunction or nonhepatic
comorbidities. Embolization alone is a palliative (i.e., noncurative) procedure. e addition of ablation for
appropriate lesions is considered a potentially curative treatment. Ablation alone may be considered for
lesions <3cm; for lesions 3–5cm, survival following combination of embolization ablation approximates that
of surgical resection.
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▶ Extrahepatic supply from branches of the the phrenic, gastroduodenal, superior mesenteric, renal capsular,
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and/or internal mammary arteries should be considered based on the location of a given lesion. In this case,
the phrenic artery was studied but did not demonstrate tumor vascularity.
▶ Whether bland embolization (as in this case) or chemoembolization with either drug-eluting beads or
lipiodol, immediate noncontrast CT aer embolization can identify suboptimally treated areas within a tumor.
In select cases, these areas may be targeted with ablation.
▶ Microwave electrodes are bipolar and therefore do not requiregrounding pads. Unlike radiofrequency ablation
in which heat is created passively by frictional agitation, microwave provides active heating. is provides a
more reliable ablation defect, but it may also be more likely to injure adjacent structures such as bile ducts in
the liver or bronchi in the lung leading to bronchopleural stula in centrally located lung lesions.
Management
▶ Compared to radiofrequency ablation, microwave ablation results in higher temperatures, faster ablation
times, and larger ablation volume. For larger tumors, multiple electrodes can be placed simultaneously.
▶ When ablation alone is performed, triple-phase CT immediately aer ablation may identify untreated areas.
Adequate ablation zone should include a margin of 0.5–1cm.
▶ Patients with hepatocellular carcinoma have a very high rate of recurrence due to the underlying eld defect
(parenchymal damage) of cirrhosis and must be followed closely.
Further Reading
Elnekave E, Erinjeri JP, Brown KT, etal. Long-term outcomes comparing surgery to embolization-ablation for treatment of
solitary HCC <7cm. Ann Surg Oncol. 2013; 20(9):2881–2886.
Wang X, Erinjeri JP, Jia X, etal.Pattern of retained contrast on immediate postprocedure computed tomography (CT) aer
particle embolization of liver tumors predicts subsequent treatment response. Cardiovasc Intervent Radiol. 2013; 36(4):c.
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Case 22
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History
▶ A60-year-old male with metastatic colon cancer status post recent pulmonary metastatectomy is referred to
you with the positron emission tomography (PET)/computed tomography (CT) scans shown in Figures22.1
and 22.2. What are the treatment options for this patient?
Figure 22.1
Figure 22.2
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Case 22 Lung Ablation
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Figure 22.3
Figure 22.4
Figure 22.5
Findings
▶ Local tumor recurrence at the staple line (Fig.22.3, white arrow).
▶ Follow-up PET/CT aer pulmonary metastatectomy demonstrates a nodular area of uorodeoxyglucose
(FDG) avidity (arrows) consistent with local tumor recurrence (Fig. 22.3).
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▶ Lung ablation was performed Fig. 22.4. Intraprocedural images (le to right) demonstrate the nodule adjacent
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to the wedge resection site in the right lower lobe followed by an image with a cryoablation probe within the
lesion.
▶ A3-month postablation PET/CT (Fig. 22.5) demonstrates interval decrease in size of the nodule with no
residual FDG-avidity (arrows).
Teaching Points
▶ Indications for lung ablation include the following:
■ Early-stage lung cancer in nonsurgical candidates
■ Local tumor recurrence in a previously radiated or postsurgical site
■ Pain palliation in pleural-based disease
▶ Complications include the following:
■ Pneumothorax
■ Hemoptysis (very rarely massive)
■ Broncho-pleural stula
▶ Similar to considerations with lung biopsy, trajectory should avoid vital structures and limit the number of
pleural punctures (see Case 7).
▶ An ablation margin of at least 1.0cm is recommended to minimize the likelihood of marginal recurrence.
▶ When utilizing microwave or radiofrequency ablative techniques, a ground glass opacity surrounding the
target lesion is expected immediately aer treatment and corresponds to the ablation zone. With cryoablation,
the iceball can be seen as a low-density structure around the cryoprobe.
Management
▶ Most practitioners recommend follow-up imaging (CT or PET/CT) at 3 and 6months, and every 6months
thereaer.
▶ FDG avidity and ground glass opacity surrounding the target lesion may persist on the 3-month PET/CT,
which is used primarily as a baseline for comparison for future scans.
▶ Local tumor recurrence is suspected if new nodular area of FDG avidity is seen not attributable to
postablation changes (the latter is typically seen as a thin rim of FDG avidity surrounding the target lesion).
▶ Local tumor recurrences aer ablation can and may be retreated with ablation if identied early.
Further Reading
Pua BB, ornton RH, Solomon SB. Ablation of pulmonary malignancy:current status. J Vasc Interv Radiol. 2010;
21:S223–S232.
Sharma A, Abtin F, Shepard JA. Image-guided ablative therapies for lung cancer. Radiol Clin North Am. 2012; 50:975–999.
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History
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▶ A70-Year-Old Female Presents with Hematuria
Figure 23.1
Case 23
Figure 23.2
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Case 23 Renal Cell Carcinoma Treated with Cryoablation
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Figure 23.3
Figure 23.4
Figure 23.5
Findings
▶ Magnetic resonance imaging (MRI) demonstrates a well-circumscribed lesion within the le kidney
demonstrating enhancement pattern suspicious for renal cell carcinoma (Fig. 23.1).
▶ Cryoablation was planned to treat this lesion. However, given the proximity of the lesion (Fig. 23.3, white
arrows) to the colon (black arrow), instillation of saline between the colon and renal lesion, was used to
separate the two in order to protect the colon from the ablative energy.
▶ Aneedle (white arrow, Fig. 23.4) has been placed between the colon and renal lesion (black arrow) with gentle
saline infusion showing some separation of the two organs.
▶ Amore caudal computed tomography (CT) image shows saline (open arrow) creating a potential space
between the target lesion (white arrow) and colon (black arrow, Fig. 23.5).
Figure 23.6
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