The utility of PET/CT in large vessel vasculitis

Infectious Aortitis on 18 F-FDG PET/CT

ABSTRACT

Infectious aortitis is a challenging radiographic diagnosis due to overlapping features with the noninfectious category. We present a case of a 58-year-old woman who tested positive for SARS-CoV-2 and Streptococcus pneumoniae bacteremia. 18 F-FDG PET/CT demonstrated large vessel vasculitis involving the thoracic, abdominal aorta, and the brachiocephalic branches of the aortic arch, and an incidental subcutaneous abscess in the right arm. Standard of care treatment was administered. Within a week, a drastic improvement of the wall thickening was noted, which can be, regardless of the biological markers, a surrogate marker of an infectious aortitis.

Imaging Response to Treatment in Rheumatology

This article highlights the crucial role of various imaging techniques in the diagnosis and monitoring of rheumatologic diseases. It provides an overview of the different modalities available for imaging rheumatic diseases, the disease processes they are able to demonstrate, and their utility in the monitoring response to therapy. It emphasizes the need for a multifaceted approach that combines radiography, ultrasound, MR imaging, and PET imaging to gain a comprehensive understanding of disease progression and treatment response. Standardized grading systems along with quantitative imaging techniques are playing an increasing role in monitoring disease activity and assessing response to therapy.

[18F]FDG PET/CT for identifying the causes of fever of unknown origin (FUO)

Fever of unknown origin (FUO) continues to be a challenging diagnosis in clinical medicine. It has more than 200 known causes, including infections, autoimmune diseases, neoplasia, and other miscellaneous disorders. Despite the development of a wide range of diagnostic tools, a specific diagnostic algorithm for FUO is not yet available. However, [18F]FDG PET/CT, which yields information on cellular metabolism, in addition to details of organ anatomy, has been shown to be successful in the FUO investigation. This study highlights the uses of [18F]FDG PET/CT in diagnosing various causes of FUO. [18F]FDG PET/CT has been increasingly used to detect septic infections, sterile inflammatory processes, and malignancies, occupying a significant portion of the known causes of FUO. It has led to a more definitive identification of the etiology of FUO and accurate clinical management. However, more in-depth studies are crucial to understanding if [18F]FDG PET/CT can be used in the work-up of FUO.

Von Willebrand factor: a possible biomarker for disease activity in vasculitis

OBJECTIVE

Inflammation markers, e.g. C- reactive protein (CRP) and sedimentation rate, can be normal despite active vasculitis. Von Willebrand factor (vWF) is secreted from endothelial cells in response to vascular damage. Some reports suggest increased vWF levels in vasculitis. This study aimed to evaluate vWF serum concentration in vasculitis patients as a possible biomarker of disease activity and to review the current literature.

METHOD

Adult patients with systemic vasculitis were prospectively enrolled. Disease activity was recorded using the Birmingham Vasculitis Activity Score (BVAS) version 3. Blood group-adjusted vWF antigen serum level was evaluated at diagnosis and, when available, after treatment.

RESULTS

Twenty-five vasculitis patients were compared to 15 healthy controls. The mean age of patients was 56 ± 17 years and 56% were women. Forty percent had anti-neutrophil cytoplasmic autoantibody-associated vasculitis, 20% giant cell arteritis, 16% polyarteritis nodosa, 8% Takayasu arteritis, and the rest had other vasculitides. The mean disease duration was 3.4 ± 4.8 years. Mean vWF was higher in patients with active vasculitis than in healthy controls (212 ± 81% vs 106 ± 26%, p < 0.001). vWF levels directly correlated with BVAS. In 13 patients with active vasculitis who reached remission or low disease activity after treatment, vWF level at follow-up decreased significantly. In three out of five patients who were treated with interleukin-6 inhibitors, vWF was elevated despite normal CRP levels, while vasculitis was clinically active.

CONCLUSION

vWF antigen serum level is increased in active vasculitis and could potentially serve as a biomarker for active disease.

The role of 18F-fluorodeoxyglucose PET/computed tomography in the diagnosis and monitoring of large vessel vasculitides - a review article

In the last two decades, advancements in positron emission tomography (PET) technology have increased the diagnostic accuracy of patients with large-vessel vasculitis (LVV). Numerous systematic reviews and meta-analyses have been conducted, and patients suspected of having LVV can be diagnosed earlier with 18F-FDG PET. Two subtypes, giant cell arteritis (GCA) and Takayasu arteritis (TA), will progress when their response to corticosteroids and enhanced immunosuppression is inadequate. In the majority of patients, disease activity cannot be monitored solely through laboratory procedures; consequently, glucose metabolism may be a source of potential biomarkers. In this article, we discuss the current state of 18F-FDG PET/CT imaging standards.

Fluorodeoxyglucose-positron emission tomography/computed tomography-positive ear lesions responsive to immunosuppressive therapy in a patient with otitis media with antineutrophil cytoplasmic antibody-associated vasculitis

A 74-year-old woman presented with vertigo, left-beating nystagmus, and auditory disturbance 4 months prior, in whom a former physician suspected Meniere's disease. Her signs and symptoms mildly improved with a moderate dose of glucocorticoids, which was eventually tapered. Fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) was performed 12 days prior to routine examination. Remarkable FDG uptake was observed in the surrounding areas of the bilateral Eustachian tubes and left middle ear, which was only partially detected on magnetic resonance imaging. The patient also tested positive for myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA). She was admitted to our hospital and diagnosed with otitis media with ANCA-associated vasculitis (OMAAV) based on the classification criteria. Four months after immunosuppressive therapy, the abnormal ear findings were not observed on follow-up FDG-PET/CT. The clinical course of this case suggests that FDG-PET/CT can detect occult ear involvement better than do other modalities in patients with OMAAV. In addition, FDG-PET/CT-positive ear lesions responded to immunosuppressive therapy. Therefore, FDG-PET/CT can help distinguish OMAAV from other ear diseases with non-inflammatory aetiologies and detect occult treatment-responsive OMAAV lesions in the clinical setting.

Differentiation of lower limb vasculitis from physiological uptake on FDG PET/CT imaging

PURPOSES

To analyze the difference of 2-deoxy-2-[¹⁸F]fluoro-D-glucose (¹⁸F-FDG) uptake between vasculitis and non-vasculitic patients in PET/CT imaging and the factors related to vascular uptake in non-vasculitic patients. To investigate the feasibility of identifying vasculitis of the lower limb and physiological uptake with delayed imaging.

PROCEDURES

Among 244 patients who underwent PET/CT examination, imaging features of patients with or without vasculitis were retrospectively analyzed. The factors related to FDG uptake in the lower limb vessels of non-vasculitic patients were analyzed. Another 44 patients with suspected systemic vasculitis in PET/CT were prospectively studied to analyze the efficacy of delayed imaging on differentiating vascular uptake in lower limbs.

RESULTS

In PET/CT imaging of patients with vasculitis, involvement of trunk vessels showed segmental or diffuse FDG distribution. Lower limb vascular involvement showed reticular uptake accompanied by nodular or patchy changes. In non-vasculitic patients, vascular uptake mainly showed linear uptake in lower limb vessels and there was no significant difference in uptake degree compared with vasculitis patients. Body weight and interval time were the independent influence factors of vascular uptake in lower limbs of non-vasculitic patients. In delayed imaging, lower limb vasculitis all showed reticular uptake and physiological uptake all showed a linear pattern. ROC analysis showed the change rate of SUV_max (≥ 20%) between early and delayed imaging could delineate physiological vascular uptake with a sensitivity of 100% and specificity of 81.0%.

CONCLUSIONS

When PET/CT is used for the diagnosis and classification of vasculitis, the physiological uptake of lower limb vessels may mislead the diagnosis. PET/CT imaging features or delayed imaging improved diagnostic efficacy.

Diagnostic value of FDG-PET/CT in fever of unknown origin

Background

Fever of unknown origin (FUO) is a challenging clinical problem in medicine that needs collaboration of various diagnostic techniques to establish the accurate diagnosis. We evaluated the diagnostic performance of 18F-FDG PET/CT in patients who presented themselves with FUO. Our study included 40 patients with FUO who underwent PET/CT examination and their results were compared to the results of laboratory, histopathological, microbiological investigations and/or response to therapy.

Results

The final diagnosis included malignancy in 20 patients (50%), infectious causes in 7 patients (17.5%) and non-infectious inflammatory causes in 6 patients (15%). Fever resolved without diagnosis in 4 patients (10%), while no definite diagnosis was reached in 3 patients (7%). PET/CT successfully contributed to diagnosis of 35 out of 40 patients with diagnostic accuracy of 87.5%. The sensitivity, specificity, positive predictive value and negative predictive value of PET/CT in our study were 93.5%, 66.7%, 90.6% and 75%, respectively.

Conclusion

PET/CT is a useful tool to investigate and diagnose the cause of FUO. It provides information that can guide the treatment strategy of the patients.

Successful treatment of a patient with Takayasu's arteritis complicated with Crohn's disease with ustekinumab: A case report

A 17-year-old woman was referred to our department with fever, general malaise, and weight loss. She was diagnosed with Takayasu arteritis (TAK) and Crohn's disease (CD) following positron emission tomography-computed tomography (PET-CT) and colonoscopy, respectively. Serological human leukocyte antigen (HLA) typing revealed HLA-B52 positivity. Initial treatment with prednisolone (0.5mg/kg) was insufficient; therefore, ustekinumab and 5-aminosalicylic acid were added. This treatment achieved prednisolone free remission for both diseases, as confirmed by PET-CT and colonoscopy. Although treatment guidelines for TAK and CD have been previously established, treatment of patients with TAK with coexisting CD is controversial. Our case suggests that ustekinumab has the ability to achieve TAK remission in addition to its therapeutic effect on CD.

Subclavian Artery: Anatomic Review and Imaging Evaluation of Abnormalities

The subclavian artery is an important structure that may be overlooked at CT of the chest and neck, in part because of its anatomic location at the periphery of the field of view but also because the clinical indication for CT examinations infrequently directs attention specifically to evaluation of the subclavian artery. As with all arteries, the subclavian artery has the potential to be involved in a variety of abnormalities, including pseudoaneurysms, dissections, stenosis or thrombosis, and vasculopathies. In addition, the subclavian artery can be secondarily involved as a collateral pathway because of an abnormality elsewhere. The subclavian artery may also be involved in surgical procedures to supply blood to other sites in the body or as an arterial access site. In these cases, recognizing the postsurgical appearance of the subclavian artery has become increasingly complex because of the use of the artery in an increasing number of procedures. Recognizing expected postoperative changes remains important to avoid mistaking them for abnormalities. The authors describe the imaging appearance of the normal anatomy of the subclavian artery and its anatomic variants, related abnormalities, and important postsurgical considerations. ^©RSNA, 2022.

Distribution patterns of arterial affection and the influence of glucocorticoids on 18F-fluorodeoxyglucose positron emission tomography/CT in patients with giant cell arteritis

Background

Giant cell arteritis (GCA) with the involvement of extracranial vessels is increasingly coming into focus. Isolated aortic involvement in the acute phase of GCA is probably more frequent than estimated because only a minority of patients show typical symptoms. ¹⁸F-fluorodeoxyglucose positron emission tomography/CT (PET/CT) is a reliable imaging tool to diagnose patients with extracranial GCA. The aim of this retrospective study was to quantify arterial involvement at the onset of a newly diagnosed GCA by PET/CT and to evaluate the influence of glucocorticoid (GC) treatment on the diagnostic performance of this imaging technique.

Methods

The study included 60 patients with GCA at the onset of a GCA. All patients had undergone a PET/CT scan. 44 patients were GC naïve and 16 patients received GC.

Results

The most affected arteries were the ascending aorta (72%), followed by the brachiocephalic trunk (62%), aortic arch (60%) and descending aorta (60%). The aorta and its branches showed an inflammatory involvement in 83.3% of patients. A singular affection of the aorta and the brachiocephalic trunk was revealed in 20% of cases. GC-naïve patients (95.5%) had more frequently affected arteries compared with GC-treated patients (50%).

Conclusion

Our study showed the frequent involvement of the thoracic aorta and brachiocephalic trunk in patients with GCA using PET/CT. Since these vascular compartments cannot be visualised by ultrasound, we advocate screening imaging of the aorta with PET/CT when GCA is suspected. Because the use of GC is associated with a marked decrease in the inflamed vascular segment in GCA, PET/CT should be performed as soon as possible.

Utility of PET/Computed Tomography in Infection and Inflammation Imaging

The role of nuclear medicine for noninvasive assessment of infection and inflammation is well established. The role of nuclear medicine is limited to initial diagnosis, recurrence, and response assessment of infections and inflammations such as tuberculosis, sarcoidosis, vasculitis, osteomyelitis, immunoglobulin G4-related diseases, and coronavirus disease 2019, as the specificity is affected by false positivity due to physiologic fluorodeoxyglucose uptake in specific organ and nonspecific uptake in postoperative cases. PET with fludeoxyglucose F 18/CT is a well-established modality for diagnosis of fever of unknown origin helping in optimized management of the patient.

The yield of F18 FDG PET-CT for the investigation of fever of unknown origin, compared with diagnostic CT

BACKGROUND

18F-Fluoro-2-deoxy-D-glucose (FDG) positron emission tomography, with contrast enhanced CT (PET-CT), is recommended as a first or a second-line imaging method for the evaluation of patients with fever of unknown origin (FUO). We evaluated the yield of PET-CT vs. contrast enhanced CT (alone) for the diagnosis of classical FUO.

METHODS

A single center, 8-year retrospective cohort study. All hospitalized patients who underwent PET-CT for the investigation of classical FUO between 1/2012-1/2020 were included. The final diagnosis, based on clinical, microbiological, radiological and pathological data available at the latest follow-up, at least six months after discharge, was determined. For each case, we determined whether the diagnosis would have been reached based on the CT scan alone, or based on the PET-CT (thus, defining PET-CT as necessary). We compared the overall sensitivity and specificity results for both PET-CT and CT scan. Variables that were found to be significantly associated with PET-CT necessity on univariable analysis were entered into a multivariable logistic regression analysis. The results of the regression model were reported in odds ratios (OR) and 95% confidence intervals (CI).

RESULT

A total of 303 patients with classical FUO were referred for PET-CT. The final diagnoses included infectious diseases in 111/303 patients (36.5%), malignancies in 56/303 patients (18.4%) and non-infectious inflammatory conditions in 52/303 patients (17.1%). FUO resolved without diagnosis in 84/303 patients (28%). The overall sensitivity and specificity of the PET-CT scans were 88.7% and 80.9%, respectively, and for the CT scans were 75.2% and 90.2%, respectively. PET-CT had superior sensitivity vs CT (p=0.00) for all subgroups, with generally decreased specificity than CT for infections and inflammatory conditions. PET-CT was determined as necessary in 26% (79/303) of the patients. Endovascular infection, hematological malignancy and large vessel vasculitis were the only factors associated with PET-CT necessity on multivariable analysis.

CONCLUSIONS

PET-CT offers superior sensitivity with slightly decreased specificity for the diagnosis of classical FUO compared to diagnostic CT. We recommend PET-CT as the imaging modality of choice for patients with classical FUO, when endovascular infection, hematological malignancy or large vessel vasculitis are suspected.

Fused 18F-Choline PET/MRI: A potential non-invasive biomarker imaging tool in cerebral vasculitis

Primary CNS vasculitis is an inflammatory brain disease commonly misdiagnosed affecting the medium and small vessels of the CNS. Due to its broad and non-specific clinical and radiological manifestations; Its diagnosis remains challenging. New diagnostic tools and biomarkers which increase specificity and facilitate the diagnosis for patients with suspected vasculitis are highly desirable to enable physicians to start therapy that can alter its potential aggressive course like immunosuppressant.

This case report highlights the potential role of ¹⁸F-choline PET/MRI as a novel imaging tool that might help in the right clinical scenario in the diagnosis of this disease.

Furthermore, it speculates on its secondary role in monitoring the response to immunosuppressant therapy.

Large-vessel vasculitis in graft-versus-host disease: a case report

BACKGROUND

Graft-versus-host disease is a common complication seen with allogenic stem cell transplant, which is used to treat a variety of hematological malignancies. Graft-versus-host disease is an allogenic syndrome and can present in a variety of ways, including symptoms mimicking various autoimmune diseases; however, it is quite rare to see graft-versus-host disease affecting the vascular system and causing vasculitis.

CASE PRESENTATION

We describe a case of a 59-year-old Caucasian man with follicular lymphoma and diffuse large B-cell transformation who developed graft-versus-host disease post allogenic hematopoietic stem cell transplantation and later progressed to neurological complication foot drop and large-vessel vasculitis.

CONCLUSION

The life-threatening vascular complications associated with large-vessel vasculitis include arterial aneurysms and dissections, and ischemic or hemorrhagic stroke. Thus, this rare immunological association needs to be recognized and treated in a timely manner to prevent the long-term complications.

The usefulness of [18F]FDG-PET/CT in detecting and managing cancers with unknown primary site depends on histological subtype

We assessed the role of [18F]FDG-PET/CT in identifying and managing cancer of unknown primary site (CUP syndrome). We reviewed [18F]FDG-PET/CT scans of individuals with CUP syndrome recorded in clinical referral letters from 2012 to 2019. We evaluated the identification of primary tumor (PT) by [18F]FDG-PET/CT, according to histological subtype, and the impact on clinical management. The median age was 65 years, 36/64 males (56%). PTs were detected in 28/64 (44%) patients. Detection was significantly lower in patients with squamous cell carcinoma (SCC) than with other histologies combined, p = 0.034. Mean age, mean SUVmax (10.6 ± 6.0) and organ involvement were similar between patients with and without discovered PTs; and between patients with SCC and with other histologies combined. However, those with SCC were less likely than the others to present with multi-lesion involvement, p < 0.001. [18F]FDG-PET/CT interpretations apparently affected treatment of 8/28 (29%) patients with PT detected, and in none of the 35 whose PT was not discovered, p < 0.001. [18F]FDG-PET/CT appeared helpful in detecting PT in almost half the patients with CUP syndrome; the lowest rate was for patients with SCC pathology. PET/CT showed limited overall value in guiding clinical management, however benefited those with discovered PT.

Impact of unknown incidental findings in PET/CT examinations of patients with proven or suspected vascular graft or endograft infections

Vascular graft or endograft Infections (VGEI) are rare but severe complications of vascular reconstructive surgery, and associated with significant mortality and morbidity risk. Positron emission tomography/computed tomography with ¹⁸F-fluorodeoxyglucose (PET/CT) has been shown to have a high diagnostic accuracy in the detection of VGEI. In this single-center prospective cohort study, we assessed the rate and the impact on patient management of relevant unknown incidental findings in PET/CT of patients with proven or suspected VGEI, and clinical follow-up of all patients was performed. Our study results show a comparably high rate of relevant unknown incidental findings (181 in 502 examinations), with documented direct impact on patient management in 80 of 181 (44%) of all findings. PET/CT scan- and patient-based evaluation revealed impact on patient management in 76 of 502 (17%) of all PET/CT scans, and in 59 of 162 (36%) of all patients, respectively. Furthermore, PET/CT correctly identified the final diagnosis in 20 of 36 (56%) patients without VGEI. In conclusion, in proven and suspected VGEI, PET/CT detects a high rate of relevant unknown incidental findings with high impact on patient management.

Takayasu arteritis in an adolescent with Crohn's disease

Crohn’s disease (CD) and Takayasu arteritis (TA) are two distinct clinical entities. Τhe likelihood of both diseases coexisting is low, and although CD co-occurs with all types of vasculitis, TA is the most common subtype. Herein, the case of a 15-year-old female, diagnosed with TA following an initial diagnosis of CD, is reported. A review of the literature, including a systemic review of the case reports and case series of children and adolescents up to the age of 21, with both CD and TA, follows the case description. In total, 28 cases of TA and CD were retrieved. The median age of patients was 14.8 years, they were mostly females (72%) and the median time between the two diagnoses was 3.7 years. In the majority of cases, CD was diagnosed first and TA followed. Computed tomography angiography and magnetic resonance angiography were the preferred imaging modalities to assist diagnosis.

Use of 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography to successfully diagnose central nervous system vasculitis in systemic lupus erythematosus and antiphospholipid syndrome: a case report

A 53-year-old woman was admitted to our hospital for headache secondary to an acute subdural haematoma in the right cerebellar tentorium. She had been diagnosed with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) two years before presentation and was initiated on prednisolone (PSL) 40 mg/day as induction therapy, which was subsequently tapered to 5 mg/day. Her thrombocytopenia and renal impairment were managed by warfarin with a target prothrombin time-international normalised ratio of 2-3. Her history also included 5 instances of triggerless acute subdural haematoma in the right cerebellar tentorium in the preceding 8 months. Warfarin therapy was suspected as the cause of her bleeding; however, dose adjustment was ineffective. During the current admission, neither magnetic resonance imaging nor cerebral angiography could reveal the cause of the bleeding. However, spinal fluid IL-6 was 25.7 pg/mL, and ¹⁸F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography showed fluorodeoxyglucose accumulation in the right medial occipital lobe cortex in the proximity of the haemorrhage site. Based on these two findings, we suspected vasculitis as the cause of recurrent bleeding. After ruling out malignancy, re-induction therapy with intravenous cyclophosphamide 500 mg/m²/month and PSL 30 mg/day was initiated. PSL was tapered to 2 mg/day and no signs of relapse have developed at 2 years after discharge. Her clinical course also supported vasculitis as the cause of recurrent central nervous system (CNS) bleeding and we discuss the usefulness of ¹⁸F-Fluorodeoxyglucose-Positron Emission Tomography in the diagnosis and treatment of CNS vasculitis in SLE and/or APS.

PET/CT in therapy control of infective native aortic aneurysms

Infective native aortic aneurysms (INAA) are aneurysms arising from infection of the aortic wall. Treatment is demanding with 5-year survival rates between 53 and 55%. The aim of our study was to evaluate the usefulness of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in the long-term monitoring of patients with proven INAA. Fifty-three PET/CT were performed in 15 patients with INAA in this single-center retrospective cohort study and retrospective analysis of prospectively collected Vascular Graft Cohort Study (VASGRA) data. Median metabolic activity (as measured by maximum standardized uptake value, SUVmax) of the aneurysms at the initial PET/CT was high (6.8 (IQR 5.7–21.8)), and lower at the last PET/CT prior to the end of antimicrobial therapy (3.9 (IQR 2.7–6.8); n = 11) as well as in the first PET/CT after the end of the treatment (3.9 (IQR 3.0–4.4);n = 6). Compared to the course of C-reactive protein alone, PET/CT provided different (> 20% difference in trend) or altering (opposed trend) information on the course of disease in at least 14 comparisons (56%) in 11 patients (73%). The one-year and five-year freedom from all-cause lethality was 92% (95% confidence interval 57%-99%). As compared to the course of C-reactive protein, PET/CT provides different and occasionally altering information in therapy control of INAA.