FDG PET CT : "metabolic biopsy " revisited !!! Dr. C P Wong

Clinical PET Center, Hospital Authority Nuclear Medicine Unit Queen Elizabeth Hospital Hong Kong !9/11/2013

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Eur J Nucl Med (2001, Sep) 28:1336–1340

63 patients underwent FDG-PET scans for lung lesions!!either after unsuccessful biopsy or, in lesser number of cases,!when an attempt at biopsy was considered too dangerous!!follow-up by histology or clinical progress to death or minimum of 18 months!!Visual analysis --- positive / negative predictive values - 90% and 100%, respectively!!Quantitative (SUV>2.5) analysis ---- positive / negative predictive values -!90% and 85%, respectively

Eur J Nucl Med (2002 April) 29:542–546

FDG-PET scanning was performed in 50 patients!!most underwent unsuccessful biopsy of lesion outside the lung!!fewer with no attempt at biopsy as considered too dangerous!!follow-up by histology or clinical progress to death or minimum of 12 months !!visual and quantitative analysis was performed!!visual analysis --- positive / negative predictive values - 89% and 100% respectively!!quantitative (SUV>2.5) -- positive / negative predictive - 93% and 86%, respectively!

!“ FDG PET, with unique ability to differentiate benign from malignant disease, may provide a “metabolic biopsy” as an alternative to tissue biopsy and separate those requiring further investigation from those who do not”

Metabolic Biopsy : implication in 2013

Benign Malignant

SUVmax. 2.5

M1

M2 M4

M3

Illustrated Cases

M/77 !Poorly differentiated adenoCa stomach !Total gastrectomy in 1996 !Had LUQ abdominal mass in 2010 !CEA : 98 !Contrast CT : splenic mass and sacral lytic bone metastasis !!

8/2010

SUVmax. 11.2

SUVmax. 2.5

PET CT

Markedly hypermetabolic splenic mass suggesting malignancy. !Faintly hypermetabolic sacral lytic lesion. Owing to significant different FDG uptake patterns, not suggesting secondary from poorly differentiated Ca stomach and also different entity from splenic mass. !

Splenectomy : metastasis from Ca stomach !Sacral lesion biopsy : chordoma

Diffuse large B cell lymphoma

F/80 !Back pain !MRI : sacral tumor !Private PET CT : solitary malignant looking tumour in sacral body with invasion into the sacral canal and presacral space. !Chordoma has to be considered. !Possibility of a metastatic lesion is less likely since this is a solitary lesion and no primary site of malignant tumour is demonstrated. !Differential diagnosis also includes Giant Cell Tumour.

Clin Nucl Med 2008;33: 906–908

SUVmax. 5.8

Chordoma : !• rare malignant bone tumor (local erosion but low metastatic

potential) !

• arises from notochord remnants of neuraxis and vertebral bodies !

• more common in males !

• rare in patients aged <40 years !

• most commonest sites : sacrum and skull base !!

M/ 77 !presented with fever & incidental finding of RML lung mass. !blood culture : Klebsiella and Streptococcus anginosus. Completed a course of antibiotics. !CT post antibiotics : 4.2cm RML lung mass. !Biopsy : squamous cell carcinoma. !PET CT for staging.

Hypermetabolic right middle lobe CA lung. !!FDG avid RUL lung mass, suggesting intra-pulmonary metastasis.!!4.5cm non hypermetabolic left frontal lobe cerebral mass with mild midline shift to right by the mass effect. No significant perilesional edema seen. The FDG uptake pattern favors primary brain tumor. Suggest MRI correlation.!!Hypermetabolic enlarged soft tissue mass medial to the left parotid gland. This can be a Warthin 's tumor or ? secondary from Ca lung. Suggest pathological correlation.

PET CT :

MRI :

Parotid gland pathology :

M/ 64 !RUL squamous cell Ca lung !CT contrast before PET CT : !•6.5cm RUL lung mass, likely malignant

neoplasm !

•Lobulated mass at left renal sinus, worrisome for neoplasm (in particular renal metastasis in current context) !

•Several sclerotic lesions at vertebrae, bone secondaries cannot be excluded

PET CT for workup

PET CT : !Hypermetabolic necrotic Ca lung !Non FDG avid left renal mass, not suggesting secondary !Hypermetabolic left parotid gland nodule, likely Warthin’s tumor Non FDG avid sclerotic bone lesions, likely benign

Pathology

FNAC left parotid gland nodule confirmed Warthin ‘s tumor

M/73 !Metastatic adenoCa lung, failed chemotherapy !Palliative RT to mediastinum

Pericardial fluid cytology : metastatic adenoCa

F/ 78!!abdominal distension and on & off vaginal spotting x 1 year!!mild right sided abdominal pain!!P/E : pelvis mass ~ 10cm!!USG: large heterogenous pelvic mass 16cm, right hydronephrosis !!CEA : 21.6; CA125 : normal!!No histological proof so far

Large multi septated cystic mass at pelvic cavity, which is not associated with obvious FDG uptakes. These can be a tumor mass arising from adnexa such as mucinous cystadenoma / cystadenocarcinoma of ovary in current context of raised!CEA.! !Non FDG avid cystic nodule at lower anterior midline abdominal wall, this can be a Sister Mary Joseph's nodule & can be accessed for pathological correlation. !!

PET CT :

Pathology (TAHBSO + debulking)

F/ 48, Mucinous Breast Cancer

M/54 !Known CA lung and RUL lobectomy !Metastatic bilateral SCF and mediastinal lymph nodes, treated with chemoRT !Then found raised CEA ~1yr. later !

Left cerebellar mass resected !Pathology : metastatic Ca of lung primary

Factors affecting FDG tumoral uptakes in PET CT

• Histology subtypes • Histology grading • Differentiation / dedifferentiation, e.g. Thyroid Ca • Size • Non cellular components, e.g. necrosis, mucinous, fluid

space

“ Metabolic Biopsy “ has its strength and weakness…...

Clinical PET CT reporting !• Pathology & subtypes • Treatment (chemotherapy, radiation therapy &

others) • Biochemical markers : tumor markers, LDH,

WBC, Serum protein electrophoresis…...

• Co-morbidity • FDG uptakes • Size • Morphology • Artifacts

Georges-Pierre Seurat

Thank you