Fibroblast activation
protein inhibitor (FAPI) is a
quinoline-based membrane-bound
glycoprotein enzyme that is not usually expressed in normal adult tissues, except for the myometrium and sometimes the pancreas. Its expression increases in
inflammation and cancer-associated fibroblasts (CAF). As FAPI is a new molecule with a promising future, presented here is a case report of uncontrolled diabetes with
abdominal pain that showed features of
inflammation in the kidneys. The patient had been previously diagnosed with
maxillary sinusitis with Aspergillus niger and was receiving
antibiotic treatment. The urine culture performed later was negative, and the patient was referred for 18F-fluorodeoxyglucose (18F-FDG) PET Computed Tomography (CT) to look for the focus of
infection. However, as
blood sugar was 500 mg/dL,
18F-FDG PET CT could not be performed. Therefore,
68Ga-FAPI PET CT was run instead after taking the patient's written informed consent. The
99mTc-dimercaptosuccinic acid scan performed on another day confirmed the presence of
pyelonephritis bilaterally. In situations where FDG cannot be used because of
hyperglycemia,
68Ga-FAPI PET CT scan may be considered an alternative in the detection of occult
infection or
inflammation, as demonstrated in this case report.