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272 Diagnostic reporting using postradioembolization imaging
(a)
(e)(f)
(b)
(d)(c)
(h)(g)
Figure 13.10 Multifocal hepatocellular carcinoma with portal vein tumor thrombosis. (a, b) Portal vein
tumor thrombosis (arrows) depicted on portal venous phase of triphasic CT liver in trans-axial and coronal planes. (c, d) 90Y PET/CT shows, in high resolution, subtle 90Y activity within the portal vein tumor
thrombus, which is unlikely to be effective. (e, f) Bremsstrahlung SPECT/CT was indeterminate for the
presence or absence of focal activity within the portal vein tumor thrombus due to visual interference
from adjacent liver activity. (g, h) Follow-up triphasic CT liver 3 months after radioembolization shows
progression of the portal vein tumor thrombosis, depicted here in the portal venous phase in transaxial and coronal planes. This clinically validates the 90Y PET/CT nding of subtle, ineffective activity
within the portal vein tumor thrombosis.
closely adjacent to the liver serosa such as the gastric
13.4.4 TECHNICAL FAILURE
pylorus, proximal duodenum, or gallbladder fundus.
Due to the poor spatial resolution of bremsstrahlung
SPECT/CT, these areas are oen indeterminate for
the nontarget activity. e improved spatial resolution of 90Y PET partially ameliorates this problem
with additional quantitative capability.
e fundamental premise of radioembolization is
to balance safety and ecacy within a multidisciplinary framework. Technical failure has occurred
when the 90Y activity biodistribution is adversely
inconsistent with pretherapy planning expectations.
13.4 Principles of diagnostic reporting / 13.4.4 Technical failure 273
(a)
(c)
(a)
(b)
Figure 13.11 Nontarget 90Y activity in the proximal duodenum. 90Y PET/CT shows mild nontarget
activity in a linear morphology corresponding to the proximal duodenal wall. Nontarget activity can
be appreciated both on the fused 90Y PET/CT (a) and 90Y PET image (b). 90Y PET quantication was not
performed. The patient was clinically asymptomatic on follow-up.
(b)
(d)
Figure 13.12 Nontarget 90Y activity in the untargeted left lobe. (a) Large hypovascular hepatocel-
lular carcinoma of the right lobe depicted by catheter-directed CT of the right hepatic artery. (b)
Bremsstrahlung SPECT/CT shows, in low resolution, subtle diffuse bremsstrahlung activity in the
untargeted left lobe (arrows). (c, d) 90Y PET/CT shows, in high resolution, nontarget activity in a nonrandom distribution conforming to the anatomy of the untargeted left lobe. The nontarget activity
was probably due to mild microsphere reux, arterioportal shunting, or both.
In other words, signicant irreversible technical
complications had occurred during radioembolization with the potential to cause severe radiomicrosphere toxicity. Technical failure is, therefore, a
serious diagnosis that should not be made without
due consideration because it implies a high likelihood of adverse clinical outcomes and also negatively impacts team morale. A diagnosis of technical
failure should prompt an urgent clinical review for
early management in terms of adjuvant treatment or
mitigative action to minimize potential toxicity.
e specic denition of technical failure differs depending on the size and distribution of the
targeted tumors and the overall treatment intent.
For tumors, technical failure generally means very
poor tumor 90Y activity coverage and early disease
274 Diagnostic reporting using postradioembolization imaging
(a)
(b
Threshold: 499018 Bq/mL
, 100 HU
progression is expected. For massive tumors, technical failure means that large regions of the tumor
are devoid of 90Y activity, excluding central necrosis.
For nontarget activity, technical failure means
that a signicant amount of 90Y activity has been
detected within nontarget tissue and severe toxicity
is likely. However, visual assessment alone is subjective and unreliable for toxicity prediction. erefore,
any nontarget activity of clinical concern should be
guided by 90Y PET absorbed dose quantication.
13.4.5 QUANTIFICATION OF
NONTARGET ABSORBED
DOSE
For clinically meaningful diagnostic reporting,
nontarget activity should be reported together
with its likelihood of toxicity. To achieve this, 90Y
PET quantication of the nontarget absorbed dose
6PT CT 3D
should be performed because visual assessment
alone is subjective. e nontarget tissue absorbed
dose provides an objective and radiobiologically
rational basis to predict toxicity, which in turn
impacts mitigative action. Nontarget activity may
be assumed to be clinically insignicant only if
visually subtle; all other cases should be objectively
supported by absorbed dose quantication.
e likelihood and severity of nontarget toxicity
depends on the organ involved and absorbed dose
biodistribution and should always be assessed on a
case-specic basis. Radiomicrosphere dose–response
data for nontarget tissue toxicity are currently scarce.
To ll this knowledge gap, dose–response experiences of external beam radiotherapy may serve as
an interim guide using mathematical extrapolations
such as the biologically eective dose (Cremonesi et
al., 2014). However, such extrapolations must be cautiously used because the radiobiology of radioactive
6
Avg: 1076665 Bq/mL, 19 HU
Max: 3424908 Bq/mL, 100 HU
Volume: 22.47 cm
Threshold: 499018 Bq/mL
) (c)
6PT CT 3D
6
Avg: 1076665 Bq/mL, 19 HU
Max: 3424908 Bq/mL, 100 HU
Volume: 22.47 cm
Figure 13.13 Absorbed dose quantication of nontarget activity in the gastric pylorus by 90Y PET.
3
6PT CT 3D
3
6
Avg: 1076665 Bq/mL, 19 HU
Max: 3424908 Bq/mL
Volume: 22.47 cm
Threshold: 499018 Bq/mL
3
A volume-of-interest was dened in the pylorus by volumetric isocontour thresholding and its mean
radioconcentration obtained. After decay correction to the time of radioembolization, a mean
absorbed dose of approximately 65 Gy was obtained. This patient developed chronic abdominal
pain and pyloric ulceration seen on endoscopy 3 months later. Parts a, b, and c are axial, coronal, and
sagittal reconstructions, respectively.
13.4 Principles of diagnostic reporting / 13.4.6 Verication of absorbed doses 275
(a) (b)
microspheres is dierent to that of external beam
radiotherapy and also between dierent types of
radioactive microspheres.
90
Y PET absorbed dose quantication in hollow viscus is challenging. A simple solution may
be to dene a volume-of-interest to obtain its mean
radioconcentration. is is then decay corrected
and the 90Y absorbed dose coecient (approximately 50 Gy per GBq/kg) applied to obtain its
mean absorbed dose (Figure 13.13). Using this
method, preliminary data for 90Y resin microspheres found that approximately 49 Gy to a localized area of the gastric wall may cause gastritis,
65 Gy may result in ulceration, whereas less than
18 Gy may be asymptomatic; 53 Gy to the duodenum may cause duodenitis (Kao et al., 2013b). Due
to the current paucity of data, further research into
nontarget dose–response is warranted to guide
toxicity prognostication.
13.4.6 VERIFICATION OF ABSORBED
DOSES
Modern personalized radioembolization utilizes
patient-specic tomographic parameters to optimize the brachytherapy radiation plan. If a scientically sound and meticulous method of pretherapy
radiation planning had been used for 90Y activity
prescription (e.g., “artery-specic SPECT/CT partition model”; Kao et al., 2012), then technical success means that the intended radiation plan may
be assumed to be valid within the general limits of
Figure 13.14 Absorbed dose quantication of a portal vein tumor thrombus by 90Y PET. (a) Triphasic
CT liver in the arterial phase demonstrates a large contrast-enhancing portal vein tumor thrombus (arrow). (b, c) A volume-of-interest approximating the activity boundaries of the portal vein
tumor thrombus was dened by volumetric isocontour thresholding and its mean radioconcentration obtained. After decay correction to the time of radioembolization, a mean absorbed dose of
approximately 248 Gy was obtained. (d) Follow-up triphasic CT liver in the arterial phase at 4 months
postradioembolization shows a slight decrease in lesion size and a complete lack of contrast enhancement within the portal vein tumor thrombus (arrow), suggesting a complete response; this clinically
validates the mean radiation absorbed dose quantied by
(d)(c)
90
Y PET.
276 Diagnostic reporting using postradioembolization imaging
(b)
(a)
(c)
(d
Tumor radiation absorbed dose (Gy)
umor volume (%
1600
dosimetric uncertainty (Kao et al., 2013c; Song et
al., 2015). is means that the treatment response
is expected to be in accordance to the prescribed
tissue absorbed doses. In such cases, postradioembolization verication of absorbed doses by 90Y
PET quantication is unnecessary unless for quality control, research, or dose–volume histograms,
or if the absorbed dose of a specic lesion is
Length: 3.974 cm (61.652 pts)
Length: 3.458 cm (63.652 pts)
)
Length: 2.116 cm (30.849 pts)
Length: 1.822 cm (26.550 pts)
desired, for example, portal vein tumor thrombus
(Figure 13.14).
One method of 90Y PET quantication is to
apply the “local deposition method” (Chapter
12) to obtain the mean absorbed dose and dose–
volume histogram within a volume-of-interest
(Figure 13.15) (Kao et al., 2013b; Pasciak et al.,
2014). Using this analysis, predictive dosimetry
(e)
(f)
100
90
80
)
70
60
50
40
30
20
T
10
0
0 100 200 300 400 500 600 700 800 900 1000
Volume 74.4 cm
T/N ratio 11.8
Mean 425.3 Gy
Minimum 30.1 Gy
Maximum 1618.9 Gy
11001200130014001500
3
Figure 13.15 90Y PET tumor voxel dosimetry and dose–volume histogram using the local deposi-
tion method. (a) Triphasic CT liver in the arterial phase shows a right lobe hepatocellular carcinoma
measuring 4.0 × 3.5 cm. (b) 90Y PET/CT depicts activity biodistribution in high resolution, with intense
tumor activity and low-grade activity in nontumorous liver. (c) Corresponding trans-axial slice of the
90
Y PET display used for manual contouring of tumor volume-of-interest for voxel dosimetry, indicated
by small black dots. (d) Isodose map of the corresponding trans-axial slice of the right liver lobe provides a visual representation of dose heterogeneity within the target arterial territory and displays the
full range of delivered dose from 0 Gy to >1600 Gy. (e) Follow-up triphasic CT liver in arterial phase
5.5 months later shows a noncontrast-enhancing hypodensity with signicant size reduction to 2.1
× 1.8 cm, representing a complete response. (f) Dose–volume histogram generated by 90Y PET voxel
dosimetry from the tumor volume-of-interest shown in (c). Mean, minimum, and maximum tumor
absorbed doses were 425 Gy, 30 Gy, and 1619 Gy, respectively; D70 was >210 Gy, where D70 is the
minimum absorbed dose to 70% tumor volume.
13.5 Economics of 90Y PET 277
based on Tc-99m MAA SPECT/CT was shown to
be accurate for tumor absorbed doses with a low
mean bias of +6.0% (95% condence interval –1.2%
to +13.2%) in a subset of highly select tumors (Kao
et al., 2013b).
Tissue mean absorbed doses may also be calculated using simple count ratios to obtain the “true”
tumor-to-normal liver (T/N) ratio, analogous to
that estimated by Tc-99m MAA during pretherapy planning. Input of the true T/N ratio back
into tissue masses and lung shunt fraction as per
Medical Internal Radiation Dose (MIRD) macrodosimetry (i.e., “Partition Model”) (Ho et al., 1996)
will obtain more accurate tissue mean absorbed
doses. Using this analysis, good correlations were
found for mean absorbed doses by Tc-99m MAA
compared with 90Y PET for both tumor (r = 0.64;
p < .01) and nontumorous liver (r = 0.71; p < .001)
(Song et al., 2015).
Semiempirical 90Y activity prescription such as
the “body surface area method” for resin microspheres has no radiobiologically rational basis to
establish any dose–response relationships, unless
90
Y PET quantication is retrospectively performed.
As an inherent conceptual limitation of the semiempirical paradigm, patient-specic tissue absorbed
doses are unknown at the time of 90Y activity prescription. At the discretion of the treating team,
90
Y PET quantication may be retrospectively performed to discover what the tissue absorbed doses
actually were, albeit too late for any absorbed dose
modication. is situation is similar for glass
microspheres, where 90Y activity prescription is
generally based on a mean absorbed dose averaged
across the entire target arterial territory.
For the lung, absorbed dose verication by 90Y
PET is more technically challenging. First, tidal
breathing may overestimate the lung absorbed
dose at the lung bases due to “spill in” of activity from the liver dome (Figures 13.5 and 13.6).
Respiratory gating may be a possible solution
(Mamawan et al., 2013). Second, the lung radioconcentration within the PET eld-of-view may
be too low for accurate quantication. However, it
may be theoretically possible to indirectly calculate
the total lung activity as the dierence between
the total injected activity and whole-liver activity
quantied by 90Y PET. e lung mean absorbed
dose may then be calculated using the patientspecic lung mass estimated by CT densitovolumetry (Kao et al., 2014b).
13.5 ECONOMICS OF 90Y PET
A practical challenge of 90Y PET is its relatively
long acquisition time as compared with conventional PET tracers such as 18-uorodeoxyglucose
(FDG). Due to a very low 90Y positron fraction, a
longer acquisition per bed is preferred. Today’s
TOF scanners typically acquire 90Y PET at 15–20
minutes per bed position. If the liver is markedly
enlarged, two bed positions may be required,
increasing the total PET acquisition time to
30–40 minutes. In comparison, a whole-body
FDG PET/CT by a TOF scanner takes 20–30 minutes to complete. Hence, the economic impact of
performing such long 90Y PET scans for a single
patient cannot be ignored, especially in highthroughput PET centers.
A total scan time of 40 minutes for two-bed
positions is probably at the limit of tolerance for
most patients. Any further increase in acquisition time may risk patient discomfort, movement,
and misregistration (Figure 13.16). Unless future
research can signicantly shorten the PET acquisition time without compromising image quality,
extending the PET eld-of-view from the abdomen into the lungs will result in an impractically
long total scan time of 45–80 minutes over three
to four bed positions. Any respiratory gating will
compound the total scan time even longer.
If 90Y PET of both the lung and liver is clinically indicated, for example, patients with high
14.9 mm (2D)
14.4 mm (2D)
12.4 mm (2D)
Figure 13.16 Trans-axial PET/CT misregistration of up to 1.5 cm in the liver due to patient
movement during a 15 minutes per bed 90Y PET
acquisition.
278 Diagnostic reporting using postradioembolization imaging
lung shunting where knowledge of the true lung
absorbed dose is clinically relevant, a possible solution may be to break up the lung and liver into two
separate acquisitions to allow the patient to rest
between the two scans. All 90Y PET quantication must be decay corrected to the time of radioembolization. e overall economic feasibility of
90
Y PET will vary depending on the healthcare
nancial model and research grant availability of
each country and institution.
13.6 CONCLUSIONS
90
Y PET is technically superior to bremsstrahlung
SPECT/CT and should be preferred where available. Continuity of care is central to clinically
meaningful diagnostic reporting of postradioembolization imaging. Qualitative and quantitative
90
Y PET are interrelated and inseparable components that should be interpreted in the context of
each other. Further research on 90Y PET is required
to improve the quality of reconstructed images and
accuracy of absorbed dose quantication and to
investigate dose–response relationships in microsphere radiobiology.
ACKNOWLEDGMENTS
e following members and their institutions are
acknowledged for their contributions: Anthony
Goh and David Ng, Department of Nuclear
Medicine and PET, Singapore General Hospital,
Singapore; Jerey Steinberg, Jianhua Yan, and
David Townsend, Agency for Science Technology
and Research—National University of Singapore
Clinical Imaging Research Centre, Singapore;
Mark Goodwin, Sze Ting Lee, and Andrew
Scott, Department of Radiology, Department
of Molecular Imaging and erapy, Austin
Health, Melbourne, Australia; Meir Lichtenstein,
Department of Nuclear Medicine, e Royal
Melbourne Hospital, Melbourne, Australia; and
Richard Dowling, Department of Radiology, e
Royal Melbourne Hospital, Melbourne, Australia;
Jan Boucek, Department of Nuclear Medicine, Sir
Charles Gairdner Hospital, Perth, Australia.
REFERENCES
Cremonesi, M. et al. (2014). Radioembolization of
hepatic lesions from a radiobiology and dosimetric perspective. Front Oncol 2014;4:210.
Ho, S. et al. (1996). Partition model for estimating
radiation doses from yttrium-90 microspheres
in treating hepatic tumours. Eur J Nucl Med
23:947–952.
Jiang, M. et al. (2012). Segmental perfusion dif-
ferences on paired Tc-99m macroaggregated
albumin (MAA) hepatic perfusion imaging
and yttrium-90 (
ing studies in SIR-Sphere radioembolization:
Associations with angiography. J Nucl Med
Radiat Ther 3:122.
Kao, Y.H. et al. (2011). Imaging discordance
between hepatic angiography versus Tc-99mMAA SPECT/CT: A case series, technical
discussion and clinical implications. Ann Nucl
Med 25:669–676.
Kao, Y.H. et al. (2012). Image-guided personal-
ized predictive dosimetry by artery-specic
SPECT/CT partition modeling for safe and
effective 90Y radioembolization. J Nucl Med
53:559–566.
Kao, Y.H. et al. (2013a). Post-radioembolization
yttrium-90 PET/CT—Part 1: Diagnostic reporting. EJNMMI Res 3:56.
Kao, Y.H. et al. (2013b). Post-radioembolization
yttrium-90 PET/CT—Part 2: Dose–response
and tumor predictive dosimetry for resin
microspheres. EJNMMI Res 3 :57.
Kao, Y.H. (2013c). A clinical dosimetric perspec-
tive uncovers new evidence and offers new
insight in favor of 99mTc-macroaggregated
albumin for predictive dosimetry in 90Y resin
microsphere radioembolization. J Nucl Med
54:2191–2192.
Kao, Y.H. et al. (2014a). Non-target activ-
ity detection by post-radioembolization
yttrium-90 PET/CT: Image assessment
technique and case examples. Front
Oncol4:11.
Kao, Y.H. et al. (2014b). Personalized predic-
tivelung dosimetry by technetium-99m
macroaggregated albumin SPECT/CT for
yttrium-90 radioembolization. EJNMMI Res
4:33.
90
Y) bremsstrahlung imag-
References 279
Lhommel, R. et al. (2009). Yttrium-90 TOF PET
scan demonstrates high-resolution biodistribution after liver SIRT. Eur J Nucl Med Mol
Imaging 36:1696.
Mamawan, M.D., Ong, S.C., Senupe, J.M. (2013).
Post-90Y radioembolization PET/CT scan with
respiratory gating using time-of-ight reconstruction. J Nucl Med Technol 41:42.
Nickles, R.J. et al. (2004). Assaying
and PET imaging of yttrium-90: 1
>>34 ppm > 0.IEEE Nuclear Science
Symposium Conference Record, October
16–22, 2004; Casaccia, Italy. New York, NY:
IEEE; 2004:3412–3414.
Pasciak, A.S., Bourgeois, A.C., Bradley, Y.C.
(2014). A comparison of techniques for (90)
Y PET/CT image-based dosimetry following
radioembolization with resin microspheres.
Front Oncol 4:121.
Salem, R. et al. (2011). Research report-
ing standards for radioembolization of
hepaticmalignancies. J Vasc Interv Radiol
22:265–278.
Song, Y.S. et al. (2015). PET/CT-based dosimetry
in 90Y-microsphere selective internal radiation therapy: Single cohort comparison with
pretreatment planning on 99mTc-MAA imaging and correlation with treatment efcacy.
Medicine (Baltimore) 94:e945.
Walrand S et al. (2011). Yttrium-90-labeled
microsphere tracking during liver selective
internal radiotherapy by bremsstrahlung
pinhole SPECT: Feasibility study and evaluation in an abdominal phantom. EJNMMI Res
1:32.
Willowson, K.P., Tapner, M.; QUEST Investigator
Team, Bailey, D.L. (2015). A multicentre
comparison of quantitative (90)Y PET/CT for
dosimetric purposes after radioembolization with resin microspheres: The QUEST
Phantom Study. Eur J Nucl Med Mol Imaging
42:1202–1222.
Wissmeyer, M. et al. (2011). 90Y Time-of-ight
PET/MR on a hybrid scanner following liver
radioembolisation (SIRT). Eur J Nucl Med Mol
Imaging 38:1744 –1745.
14
The use of postprocedural imaging in
the medical management of patients
AUSTIN C. BOURGEOIS, MARCELO S. GUIMARAES, YONG C. BRADLEY,
CHRISTOPHER HANNEGAN, AND ALEXANDER S. PASCIAK
14.1 Introduction 281
14.1.1 Chapter overview 281
14.1.2 Background 282
14.2 Postprocedural imaging: ndings and
signicance 282
14.2.1 Imaging surveillance protocols 282
14.2.2 Preprocedural imaging with
prognostic signicance 283
14.2.3 Normal response to therapy 284
14.2.4 Follow-up imaging assessment
criteria in predicting treatment
response 287
14.3 Imaging of complications 291
14.3.1 Hepatic toxicity 291
14.3.2 Biliary effects 292
14.3.3 Hepatic abscess 295
14.1 INTRODUCTION
14.1.1 CHAPTER OVERVIEW
Hepatic radioembolization with yttrium-90 (90Y)
microspheres is unique in many ways compared
with other methods of treating hepatic malignancy, including the use of radiation, size of the
infused microsphere, the number of particles
administered, and variable technical considerations involved in the infusion. While radioembolization imparts some of the same procedural
14.3.4 Gastrointestinal nontarget
embolization 295
14.3.5 Radiation pneumonitis and
other sites of nontarget
embolization 296
14.4 Posttreatment
14.4.1 Evaluating nontarget
embolization with
posttreatment
14.4.2 Prognostication with
14.5 Treatment modication with
14.5.1 Interprocedural treatment
modication 299
14.5.2 Interprocedural treatment
modication 299
14.6 Conclusions 299
References 299
risks to surgical interventional and other forms
of liver-directed therapy (i.e., fulminant hepatic
failure), it can result in a variable constellation
of both normal treatment eects and possible
complications. us, image interpretation following
performed in a vacuum of clinical information
and without a robust understanding of radioembolization. is chapter provides a detailed
discussion of the imaging and correlative clinical ndings following 90Y therapy with an
emphasis on clinical relevance and underlying
mechanisms.
90
Y can be confusing, particularly when
90
Y imaging 296
90
Y imaging 296
90
Y PET/CT 297
90
Y PET/CT 299
281
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