Increased F-18 FDG Uptake in Resolving Atraumatic Bilateral Adrenal Hemorrhage (Hematoma) on PET/CT

Fluoro-2-Deoxyglucose-Positron Emission Tomography/Computed Tomography in the Diagnosis and Management of Adrenocortical Carcinoma: A 10-Year Experience from a Tertiary Care Institute

Purpose

Adrenocortical carcinoma (ACC) is a rare primary malignancy of the adrenal gland. The present study was aimed to compare the performance of fluoro-2-deoxyglucose-positron emission tomography-computed tomography (FDG-PET-CT) compared to contrast-enhanced computed tomography (CECT) in diagnosis and management of ACC.

Materials and Methods

A retrospective analysis of the PET-CT studies from January 2010 to October 2020 was performed. Patients with adrenal lesions suspicious of ACC and diagnosed cases of ACC who underwent PET-CT for staging, restaging, and surveillance were reanalyzed. The PET-CT parameters were compared with the clinical, biochemical, histopathological, and CECT parameters.

Results

The study included 96 scans performed in 77 patients (36 males, aged 40.4 ± 17.9 years). Of these, 55 scans were performed to diagnose and stage suspected ACC (30 of them diagnosed as ACC), 31 for restaging, and 10 scans for surveillance of ACC. PET/CT revealed metastases from an extra-adrenal primary in 5/55 patients. FDG-PET-CT had a sensitivity and specificity of 100% and 70% to diagnose ACC. Standardized uptake value-peak more than 5.4 had a sensitivity of 90.9% and specificity of 91.7% for differentiating ACC from non-ACC lesions, while tumor-to-liver ratio peak (TLRpeak) of 3.3 was most specific. PET-CT changed the staging in 23.3% of the patients with an accuracy of 100%. PET-CT changed the management plan in 25.8% of the patients during restaging with a sensitivity and specificity of 95.6% and 100%, respectively. For surveillance, CECT was as sensitive as PET-CT; however, PET-CT was more specific (100% vs. 97.9%).

Conclusion

FDG-PET-CT performs better than CECT in the diagnosis, staging, restaging, and surveillance of ACC.

Incidental Detection of Peri-Renal Hemorrhage on F-18 FDG PET/CT Imaging in a Patient with Polycystic Kidney Disease

A 72-year-old male patient with a history of polycystic kidney disease and lung malignancy underwent F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for the evaluation of tumor recurrence. The FDG PET/CT and subsequent non-enhanced CT scans revealed a hemorrhage in the peri-renal space of the left original kidney. Interesting in this case was the incidental detection of unexpected peri-renal hemorrhage during an oncologic assessment with FDG PET/CT.

A Case of Hemorrhagic Adrenal Pseudocyst Mimicking Solid Tumor

Patient: Female, 78

Final Diagnosis: Adrenal pseudocyst

Symptoms: None

Medication: —

Clinical Procedure: Operation

Specialty: Urology

Vasovagal-related stress immediately before FDG injection may increase bilateral adrenal FDG uptake

OBJECTIVE

To evaluate the relationship between vasovagal-related stress on positron emission tomography (PET)/CT and adrenal fludeoxyglucose (FDG) uptake.

METHODS

We reviewed the medical records of 1358 consecutive patients who underwent FDG PET/CT examinations and selected those who presented with vasovagal-related symptoms and acute hypotension immediately before FDG injection (vasovagal reflex group). Patients who underwent FDG PET/CT examinations on the same days as the vasovagal reflex group without new complaints or any adrenal lesion were used as controls. We evaluated adrenal FDG uptake visually and by means of adrenal maximum standardized uptake value (SUV(max)) and adrenal/liver (A/L) SUV(max) ratio. Next, we reviewed the FDG PET/CT images of the same 1358 patients and selected the cases presenting with bilateral avid FDG uptake.

RESULTS

4 patients were included in the vasovagal reflex group, and all of them showed bilateral avid adrenal FDG uptake visually, while 19 patients in the control group did not. The mean adrenal SUV(max) and the mean A/L SUV(max) ratio were significantly higher in the vasovagal reflex group than in the control group (p < 0.001). 10 (0.74%) patients, including 4 patients from the vasovagal reflex group, showed bilateral avid FDG uptake with normal adrenal configuration on CT.

CONCLUSION

Vasovagal-related stress immediately before FDG injection may increase bilateral adrenal FDG uptake.

ADVANCES IN KNOWLEDGE

Vasovagal-related stress may be included in the differential diagnosis of the cause of bilateral avid adrenal FDG uptake.

Metabolic and anatomic characteristics of benign and malignant adrenal masses on positron emission tomography/computed tomography: a review of literature

PET/CT with (18)F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal "incidentaloma" FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been 'indeterminately' categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.

Organizing intracerebral hematoma mimicking a recurrent brain tumor on FDG-PET

A man underwent resection of low-grade astrocytoma, followed by radiation therapy at the age of 14 years old. He had been followed up for 33 years with no finding of recurrent disease on brain images until the most recent CT and MRI scans showed a mass at the postoperative site in the left parieto-occipital lobe. 18F-FDG PET/CT showed increased uptake in the mass. Resection was conducted, and microscopic examination of the whole mass demonstrated an organizing hematoma. A provisional diagnosis of organizing hematoma should be considered, along with other benign and malignant causes of increased FDG uptake.

Molecular imaging of adrenal neoplasms

The adrenal glands are complex structures from which a variety of benign and malignant tumors may arise and are a common site of metastatic disease. Several radiopharmaceuticals are used for imaging the adrenals, including I-123/I-131 metaiodobenzylguanidine (MIBG), norcholesterol derivatives, In-111 pentetreotide and Ga-68 somatostatin analogs, [F-18]fluorodeoxyglucose, [F-18]fluorodopa, [F-18]fluorodopamine, C-11 meta hydroxyephedrine, and C-11/F-18/I-123 Metomidate (MTO) or its analogs. In this review we focus on the role of these reagents in metastatic lesions, cortical neoplasms, pheochromocytoma/paraganglioma, and neuroblastoma (NB).

Clinical features of cyst infection and hemorrhage in ADPKD: new diagnostic criteria

BACKGROUND AND OBJECTIVES

Cyst infection and cyst hemorrhage are frequent and serious complications of autosomal dominant polycystic kidney disease (ADPKD), often being difficult to diagnose and treat. The first objective of this study is to clarify the clinical features of ADPKD patients with cyst hemorrhage or infection. The second objective is to establish diagnostic criteria for ADPKD patients with cyst infection or cyst hemorrhage.

PATIENTS AND METHODS

Patients with definite cyst infection or hemorrhage were enrolled from among the ADPKD patients referred to us between January 2004 and October 2011. We investigated their symptoms, laboratory data, and the computed tomography (CT)/magnetic resonance imaging (MRI) features of infected cysts (before and after onset), normal cysts, and cysts with hemorrhage.

RESULTS

There were 24 patients with cyst infection (36 infected cysts) and 12 patients with acute cyst hemorrhage (13 bleeding cysts). White blood cell (WBC) count >10,000/μl, serum C-reactive protein (CRP) >15.0 mg/dl, and body temperature >38 °C strongly suggested cyst infection. All of the cysts with hemorrhage contained a high-density mass-like area or showed overall high density on CT, and all patients with cyst hemorrhage had abdominal pain or gross hematuria. On the other hand, infected cysts showed an increase of intensity on MRI [diffusion-weighted imaging (DWI)], while a fluid-fluid level, wall thickening, and gas were also evidence of infection. Abdominal pain and/or sequential changes on MRI after onset of symptoms were useful for localizing infected cysts.

CONCLUSION

Acute cyst hemorrhage and infection can be identified from symptoms, laboratory data, and CT/MRI findings.

CT of the adrenal gland: the many faces of adrenal hemorrhage

Adrenal hemorrhage is rarely suspected clinically, exhibits no specific clinical symptoms or laboratory findings, and yet is immediately life-threatening when bilateral. Recognition of adrenal hematomas is complicated by the variable appearance of these lesions. We survey the ways in which adrenal hematomas can appear on CT and provide strategies for differentiating hematomas from other adrenal pathologies.

Positron-emission computed tomography in cyst infection diagnosis in patients with autosomal dominant polycystic kidney disease

BACKGROUND

Cyst infection remains a challenging issue in patients with autosomal dominant polycystic kidney disease (ADPKD). In most patients, conventional imaging techniques are inconclusive. Isolated observations suggest that (18)fluorodeoxyglucose (¹⁸FDG) positron-emission computed tomography (PET/CT) might help detect cyst infection in ADPKD patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Comparative assessment of administrative databases from January 2005 to December 2009 identified 27 PET/CT scans performed in 24 ADPKD patients for suspicion of abdominal infection. Cyst infection was definite if confirmed by cyst fluid analysis. Cyst infection was probable if all four of the following criteria were met: temperature of >38°C for >3 days, loin or liver tenderness, C-reactive protein plasma level of >5 mg/dl, and no CT evidence for intracystic bleeding. Episodes with only two or three criteria were grouped as "fever of unknown origin".

RESULTS

Thirteen infectious events in 11 patients met all criteria for kidney (n = 3) or liver (n = 10) cyst infection. CT was contributive in only one patient, whereas PET/CT proved cyst infection in 11 patients (84.6%). In addition, 14 episodes of "fever of unknown origin" in 13 patients were recorded. PET/CT identified the source of infection in nine patients (64.3%), including 2 renal cyst infections. Conversely, PET/CT showed no abnormal ¹⁸FDG uptake in 5 patients, including 2 intracystic bleeding. The median delay between the onset of symptoms and PET/CT procedure was 9 days.

CONCLUSIONS

This retrospective series underscores the usefulness of PET/CT to confirm and locate cyst infection and identify alternative sources of abdominal infection in ADPKD patients.

Idiopathic unilateral adrenal hemorrhage in an elderly patient

We report the case of an 85-year-old woman who has been undergoing treatment for hypertension but has not received anticoagulation therapy. The patient was admitted to our hospital for the evaluation of a right adrenal tumor (size, 10 × 9 cm²). Preoperative contrast-enhanced computed tomography and magnetic resonance imaging findings were indicative of adrenal hemorrhage (AH). Laboratory data revealed mild anemia but no adrenal dysfunction. The final pathological diagnosis was simply idiopathic adrenal hematoma. There is no case report of exactly idiopathic AH over 80 years old. We report an unusual case of idiopathic unilateral adrenal hematoma in an elderly patient. It is important to distinguish this benign lesion from a neoplasm and to consider idiopathic AH in an adrenal tumor during differential diagnosis in elderly patients who have not received anticoagulation therapy or suffered from trauma.

Cyst infections in patients with autosomal dominant polycystic kidney disease

BACKGROUND AND OBJECTIVES

Cyst infection is a complex diagnostic and therapeutic issue in patients with autosomal dominant polycystic kidney disease (ADPKD); however, published data regarding the diagnosis and the management of cyst infections in patients with ADPKD are sparse.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective study was conducted in a referral center for patients with ADPKD in Paris, France. We identified using a computerized database all patients who had ADPKD and were admitted in the nephrology department of Hôpital Necker between January 1998 and August 2008 with likely or definite renal and/or hepatic cyst infection. Medical files of all included patients were reviewed.

RESULTS

Among 389 identified patients with ADPKD, 33 (8.4%) had 41 episodes of cyst infection, including eight definite and 33 likely cases. The incidence of cyst infections in patients with ADPKD was 0.01 episode per patient per year. Microbiological documentation was available for 31 episodes (75%), Escherichia coli accounting for 74% of all retrieved bacterial strains. Positron emission tomography scan proved superior to ultrasound, Computed tomography scan, and magnetic resonance imaging for the detection of infected cysts. Clinical efficacy of initial antibiotic treatment was noted in 71% of episodes. Antibiotic treatment modification was more frequently required for patients who were receiving initial monotherapy compared with those who were receiving bitherapy. Large (diameter >5 cm) infected cysts frequently required drainage.

CONCLUSIONS

Positron emission tomography scan will probably make the diagnosis of cyst infections easier and more accurate. Antibiotic association, including a fluoroquinolone, and the drainage of large infected cysts remain the main treatment for cyst infections.

Functional imaging of inflammatory diseases using nuclear medicine techniques

Molecular imaging with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) is increasingly used to diagnose, characterize, and monitor disease activity in the setting of inflammatory disorders of known and unknown etiology. These disorders include sarcoidosis, atherosclerosis, vasculitis, inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and degenerative joint disease. Gallium-67 ((67)Ga) citrate, labeled leukocytes with technetium-99m ((99m)Tc) or indium-111 ((111)In), and (18)F-fluorodeoxyglucose (FDG) represent the most widely used radiopharmaceutical agents. However, other preparations, such as labeled murine monoclonal antigranulocyte antibodies and labeled human polyclonal nonspecific immunoglobulin G, chemotactic peptides, interleukins, chemokines, and liposomes, have been used to image inflammation. Also, (99m)Tc nanocolloid scintigraphy has been found to be suitable for bone and joint diseases, especially RA. Among the single photon emitting imaging agents, the recommended radiotracer for abdominal inflammation has been (99m)Tc-hexamethylpropylene amine oxime (HMPAO)-labeled leukocytes. During the last several years, FDG-PET imaging has been shown to have great value for the detection of inflammation and has become the centerpiece of such initiatives. This very powerful technique will play an increasingly important role in the management of patients with inflammatory conditions. FDG-PET can provide valuable information in patients with pulmonary and extrapulmonary sarcoidosis, and is a useful tool for testing the efficacy of various treatments. FDG-PET combined with computed tomography holds great promise for assessing atherosclerosis of the large arteries. This modality is very sensitive in detecting large-vessel vasculitis and can be used to monitor the disease course. FDG-PET is also being used to study the inflamed synovial joints both in the experimental and clinical settings, especially for the investigation and management of RA and degenerative joint disease. This technique also has the potential to become the imaging modality of choice in assessing IBD, replacing radiolabeled autologous leukocyte imaging in this setting. Detection of inflammation in the lungs and airways may improve our knowledge about a multitude of disorders that affect these structures. Therefore, functional imaging, led by FDG-PET imaging, is likely to play an increasingly critical role in assessing inflammatory disorders of known and unknown etiologies, and will improve their management immensely in the future.