TUMOR FDG-PET/CT IMAGING

EXAMINATION: TUMOR FDG-PET/CT IMAGING

SCANNER: Biograph mCT flow PET/CT

RADIOPHARMACEUTICAL: 9.9 mCi F-18 Fluorodeoxyglucose (FDG) I.V.

HISTORY: 43 – year – old male with intra-abdominal leiomyosarcoma. S/P laparotomy exploration and removal of tumor on 10/7/2018, followed by 2 cycles of chemotherapy.

Restaging CT dated 17/9/2018 showed peripherally enhancing rounded necrotic residual lesion in the left upper quadrant has decreased from 6.3 x 5.4 cm to 4.8 x 3.6 cm, and stable multiple (at least 5) hypodense hepatic lesions in both liver lobes measuring up to 2.5 x 2.3 cm. The study is requested for restaging , and monitoring response to therapy.

TECHNIQUE: The patient fasted for more than 6 hours. His fasting blood glucose level, measured by glucometer before injection of FDG, was 79 mg/dL. While he lay quietly in a room Plain water (1.2 L) was given as a negative contrast after the FDG injection. A low dose – noncontrast CT scan was acquired for attenuation correction and for fusion with emission PET images to allow for anatomical localization of PET findings, and not for diagnostic purposes. Emission PET images were then obtained. The area imaged spanned the region from the skull vertex to the proximal thighs with the arms positioned above the head. The time from injection of FDG to start of imaging was 40 minutes. Transverse image reconstruction using an iterative algorithm was performed with reoriented tomograms displayed in the transaxial, coronal and sagittal planes.

FINDINGS:

ABDOMEN AND PELVIS:

  • 1
    walled hypodense left hydrochondrial mesenteric cystic lesion noted abutting the wall of splenic flexure of colon. It measures about 4.4 x 3.4 cm and showed only mild peripheral FDG-avidity at its thick wall (SUV max of about 2) with cold non-FDG-avid center.
  • 2
    Preexisting multiple hypodense hepatic lesions noted at both liver lobes, currently has no corresponding pathological FDG-avidity, probably benign i.e. hemangioma.
  • 3
    Mildly FDG-avid midline upper anterior abdominal wall healing surgical scar noted.
  • 4
    The Spleen, pancreas, and adrenal glands are unremarkable regarding any pathological FDG avid lesions.
  • 5
    Both kidneys showing physiological FDG excretion that drains into urinary bladder.
  • 6
    The stomach and bowel show physiological FDG-activity.
  • 7
    There is no sizable FDG-avid lymphadenopathy seen in the abdomen and pelvis

HEAD AND NECK:

  • 1
    On the PET study, physiological FDG activity in the surveyed parts of brain gray matter is noted
  • 2
    Bilateral FDG uptake in the medial and lateral rectus extraoccular muscles, and mylohyoid muscles which is physiological in nature.
  • 3
    Foci of brown fat uptake noted at the neck
  • 4
    Diffuse physiological FDG uptake is noted in the soft palate, tonsils, parotid, submandibular salivary glands, and vocal cords.
  • 5
    No significant FDG-avid sizable cervical or supraclavicular lymph nodes, apart from few small, mildly FDG avid likely reactive nodes.
  • 6
    FDG-avid hypodense right thyroid lobe nodule measures about 1 x 0.7 cm cm and has SUV max of 5.97 noted.

CHEST:

  • 1
    The chest wall is devoid of any metabolic activity or sizable FDG avid pathological lesions
  • 2
    Both lung fields show unremarkable FDG metabolic activity, with no FDG-avid sizable lung nodules.
  • 3
    No FDG-avid sizable lymphadenopathy in the mediastinal, hilar or axillary regions.
  • 4
    Physiological uptake is seen in the myocardium.

CHEST:

  • 1
    There are no FDG-avi​​​​d osseous lesions at the surveyed parts of the skeleton.
  • 2
    Non-FDG-avid few small sclerotic densities noted both iliac wings and neck of left femur, probably benign bone islands for follow up.

CONCLUSION:
The current PET/CT study demonstrates:

  • Thick walled hypodense left hydrochondrial mesenteric cystic lesion noted abutting the wall of splenic flexure of colon, with mild peripheral FDG-avidity at its thick wall, probably residual/recurrent/metastatic lesion vs post-operative sequel for follow up.
  • Preexisting multiple hypodense hepatic lesions noted at both liver lobes, currently has no corresponding pathological FDG-avidity, probably benign i.e. hemangioma for follow up.
  • Non-FDG-avid few small sclerotic densities noted both iliac wings and neck of left femur, probably benign bone islands for follow up.
  • Incidental finding of hypermetabolic right thyroid lobe nodule for further evaluation with high resolution neck U/S, TFT, and serum TG.

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