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positron emission tomography ( pet ) is commonly used to indentify malignant lesion in the lung .
today pet scans are performed using instruments with combined pet and computed tomography ( ct ) scanners .
the combined pet - ct scans provide images that help pinpoint abnormal metabolic activity of anatomical structures seen in a ct scan , leading to a more accurate diagnosis .
pet - ct imaging may have many advantages in the study of sarcoidosis , but very little data is available on this topic . monitoring the metabolic activity of noncaseating granulomas by pet - ct can offer an accurate tool for the evaluation of response to treatment and disease activity . notably , pet - ct has been used with great success in identifying potential sites for biopsy and in obtaining histologically diagnostic samples .
the current report demonstrates that pet - ct imaging is evolving into an accurate tool for the diagnosis and monitoring of systemic sarcoidosis .
a 42-year - old male was admitted to the respiratory department of the university of genoa with fever , chest pain , and fatigue .
total body pet- imaging revealed hypermetabolic activity in multiple organs including lungs , liver , spleen , mediastinum , and lymph node chains above and below the diaphragm [ figures 1 and 2 ] .
the standardized uptake value ( suv ) in the lesion was calculated based on the activity concentration measured at the end of the scan and corrected for patient 's body weight and dose injected as follows : suv = tissue activity ( measured counts / pixel / second )  calibration factor / injected [ f18 ] fluorodeoxy glucose ( fdg ) dose ( millicuries per kilogram of body weight ) .
surgical biopsies from the thoracic lymph nodes revealed confluent noncaseating granulomas with multinuclear giant cells , mononuclear phagocytes , and lymphocytes [ figure 3 ] .
42-year - old male with fever , chest pain , and fatigue diagnosed with sarcoidosis .
pre - treatment 18f- fdg pet - ct total body scans of the patient from the base of the skull to the thighs : ( a ) ct scan , ( b ) pet scan , ( c ) fusion coronal image , and ( d ) maximum intensity projection ( mip ) image show multiple abnormal uptakes of f18-fdg .
in particular , some abnormal accumulations of radiotracer are present at the level of right pulmonary hilum , liver , and spleen ( arrows in c ) .
42-year - old male with fever , chest pain , and fatigue later diagnosed with sarcoidosis .
pre - treatment 18f - fdg pet- ct scan , transaxial fusion image at the level of the upper abdomen shows abnormal uptakes of radiotracer in the liver and spleen ( arrows ) .
42-year - old male with fever , chest pain , and fatigue later diagnosed with sarcoidosis .
photomicrograph of the biopsy sample stained with hematoxylin and eosin shows confluent sarcoid granulomata pattern in thoracic lymph node ( arrows ) .
after the diagnosis of sarcoidosis was confirmed , the patient was initially treated with prednisone 40 mg daily for one month . over the next 5 months
therefore , oral methotrexate at a dose of 10 mg once a week was added for the next 9 months .
fifteen months after initiating therapy , the patient reported total resolution of symptoms and his repeat pet - ct scan was now normal [ figure 4 ] .
fdg scan images demonstrated a significant decrease in hypermetabolic activity in the lesion as shown by a decrease in the suv value from an initial suv of 11.2 to the follow - up study post - treatment showing a suv of 2.2 .
monitoring the metabolic activity of noncaseating granulomas by pet - ct can offer an accurate tool for the evaluation of response to treatment and disease activity .
42-year - old male with fever , chest pain , and fatigue later diagnosed with sarcoidosis .
post treatment total body 18f - fdg pet / ct scan : ( a ) ct scan , ( b ) pet scan , ( c ) fusion coronal image , and ( d ) mip image show a physiological distribution of the radiotracer and the complete disappearance of abnormal uptakes at level of right pulmonary hilum , liver , and spleen ( arrows in c ) .
there are only limited number of reports about the usefulness of pet - ct in sarcoidosis .
the objective of this paper is to highlight the clinical utility of integrated [ 18f ] fdg - pet - ct imaging , for evaluation of patients with systemic sarcoidosis by comparing baseline suv values to follow - up pet - ct findings after treatment for active sarcoidosis , and by correlating changes in pet - ct with changes in clinical status .
the suv of the fdg accumulation is used as a quantitative index for differentiating between benign and malignant lesions .
a suv of less than 2.5 is generally considered to be indicative of a benign lesion . in this case
the changes in pet - ct following treatment were in agreement with changes in clinical symptoms .
the advantage of pet - ct technique is that it can visualize tracer 's accumulation in activated inflammatory cells and simultaneously provide pet and ct images .
pet - ct could be used to accurately assess inflammation activity in sarcoidosis patients with unexplained , persistent , disabling symptoms without serological inflammation activity , and is helpful in predicting pulmonary deterioration after 1 year in untreated patients or the pulmonary improvement expected after treatment .
in addition , one study , reported 100% sensitivity of pet - ct for pulmonary and systemic sarcoidosis compared with 81% sensitivity for 67ga scintigraphy / single photon emission computed tomography ( spect ) and showed positive pet - ct results in cases with negative 67ga scans .
the current case of systemic sarcoidosis found pet - ct useful for the staging and identification of occult sites for biopsy and for the assessment of inflammatory active sarcoidosis in patients with prolonged symptoms .
pet - ct provides better visualization of extra - thoracic sites of active sarcoidosis , such as , when the lesion is in the mediastinum , liver , spleen , and lymph nodes and when the diagnosis is extremely difficult because only one organ that is initially involved is in an uncommon location , or when a biopsy is not possible , or an occult location for biopsy sample is found .
therefore , pet - ct has been used in video - assisted thoracoscopic surgery procedures with great success in obtaining diagnostic biopsy samples .
pet - ct study also has a role in the clinical management of patients with chronic persistent sarcoidosis , since it may identify which patients still have active inflammation that may respond to therapy .
it may also identify which patients may require prolonged treatment with anti - inflammatory agents such as infliximab .
thus , pet - ct is a valuable adjunct to clinical evaluation for monitoring the response to treatment in these patients .
angiotensin - converting enzyme ( ace ) was not performed because the diagnostic and prognostic usefulness of the serum ace is questionable . in a study of 1941
patients with sarcoidosis , 1575 healthy control subjects , and 1355 patients with other diseases , the sensitivity of an elevated serum ace for the diagnosis of sarcoidosis was 57% , specificity 90% , positive predictive value 90% , but negative predictive value was only 60% .
therefore , this test is not adequately sensitive to be useful for diagnostic screening of sarcoidosis or for managing disease . because of this
pet - ct has proved to be of special interest in the detection of cardiac involvement .
inhibition of the physiological myocardial uptake with heparin injection or appropriate diets could enable the detection of cardiac sarcoidosis active lesions with total body pet - ct scan .
pet has been reported to have a high sensitivity of 100% and a specificity of 81.5 - 90.9% .
blankstein et al . , found that the presence of focal perfusion defects and uptake on cardiac pet - ct identified patients at higher risk of death or ventricular tachycardia .
these findings offer prognostic value beyond japanese clinical criteria , the presence of extra - cardiac sarcoidosis , and left ventricular ejection fraction .
in fact an increased fdg in the myocardium is prognostically important as this finding is associated with increased rate of death / ventricular tachycardia .
for example , pet - ct can be positive for both malignancy and sarcoidosis in a patient with both conditions , such as a patient with the  sarcoidosis - lymphoma syndrome  .
further prospective multicenter studies are needed to refine the clinical applications of pet - ct in patients with sarcoidosis and drive the field forward .
this report demonstrates that pet - ct imaging is evolving into an accurate tool for the diagnosis and monitoring of systemic sarcoidosis .
crucially , total body pet scanning must be suggested to : i ) provide a more comprehensive image of sarcoidosis activity closely related to clinical findings , ii ) assess response to antiinflammatory therapy in sarcoidosis , iii ) identify sites for diagnostic biopsy in patients without apparent lung involvement , and iv ) detect cardiac involvement .
positron emission tomography ( pet ) in combination with computed tomography ( pet - ct ) is commonly used to identify malignant lesion in the lung . 
 despite there being only a few reports in literature , pet - ct imaging may have many advantages in the study of sarcoidosis , being useful in the diagnosis as well as in monitoring the response to treatment . 
 the object of this case report is to highlight the clinical utility of integrated pet - ct imaging for evaluation of patients with systemic sarcoidosis and for comparing baseline findings to follow - up readings .