Diffusion-weighted MRI and PET–CT in the follow up of chronic periaortitis

Application of apparent diffusion coefficient of extraocular muscles from diffusion tensor imaging scanning in the assessment of disease activity of thyroid eye disease

PURPOSE

To evaluate the utility of apparent diffusion coefficient (ADC) values of extraocular muscles (EOMs) in differentiating activity of thyroid eye disease (TED).

METHOD

Forty-two TED patients who underwent diffusion tensor imaging(DTI) were retrospectively enrolled in this study, including 29 patients in analysis group and 13 patients in validation group. The mean, maximum and minimum ADC value of each EOM were regarded as ADCmean, ADCmax and ADCmin. The difference between ADCmax and ADCmin was regarded as △ADC. The correlations between ADCmean or △ADC of each EOM and clinical activity score (CAS) were assessed.

RESULTS

In analysis group, ADCmean differed between active and inactive eyes and positively correlated with CAS in IR (P < 0.05), not in SR,LR and MR(all p > 0.05). While △ADC differed between two groups and negatively correlated with CAS in all EOMs (all P < 0.05). ADCmean predicted active disease at cut-off value of 1259.3 × 10-6mm2s-1 with sensitivity of 66.7% and specificity of 71.4% in IR[area under curve = 0.667, P < 0.05]. △ADC predicted disease activity in all EOMs [area under curve 0.658-0.746,all P < 0.05]. The cut-off values of △ADC were 382, 823,520 and 572 × 10-6mm2s-1 with sensitivity of 80.0%, 50.0%, 43.3%, 83.3% and specificity of 67.9%, 85.7%, 89.3%, 60.7% in SR, IR, MR, and LR respectively. There were no significant differences in the predictive efficacy among all cut-off values.

CONCLUSIONS

Our results showed that DTI is a valuable tool in the assessment of disease activity of TED. Both ADCmean of IR and △ADC of all four EOMs can be used in discriminating disease activity with the same predictive power.

Imaging of IgG4-related disease in the extracranial head and neck

PURPOSE

Immunoglobulin G4-related disease (IgG4-RD) is a newly defined fibro-inflammatory multisystemic condition defined by a triad of diagnostic criteria based on clinical presentation, biochemical and histopathological findings. Whereas some subsites of this disease have been well described in the literature so far (e.g. pancreas, kidneys, retroperitoneum, salivary glands), more recently identified anatomical sites of involvement in the head and neck are less well understood (e.g. nose, paranasal sinuses).

METHOD

This pictorial review details the imaging appearances of extracranial IgG4-RD in the Head & Neck. Multimodality imaging appearance and features are presented, with reference to the published literature to date.

RESULTS

Following a subsite-based approach, we present both the most common and the more rarely encountered imaging patterns of IgG4-RD in the extracranial head and neck, along with the relevant differential diagnoses to consider. Our institutional experience not only cements what is already known in the existing literature on this topic, but also reveals new imaging features of IgG4-RD, notably in the sinonasal tract.

CONCLUSIONS

This pictorial review of extracranial head & neck IgG4-RD will enable radiologists to recognise the features of this condition and propose it as a differential diagnosis to include alongside other probable entities. It establishes the place of the radiologist in the diagnosis and management of IgG4-RD.

Retroperitoneal Fibrosis and its Differential Diagnoses: The Role of Radiological Imaging

Background Retroperitoneal fibrosis is a rare disease with an incidence of 0–1/100 000 inhabitants per year and is associated with chronic inflammatory fibrosis of the retroperitoneum and the abdominal aorta. This article sheds light on the role of radiological imaging in retroperitoneal fibrosis, names various differential diagnoses and provides an overview of drug and surgical treatment options.

Methods A literature search for the keywords “retroperitoneal fibrosis” and “Ormond’s disease” was carried out in the PubMed database between January 1, 1995 and December 31, 2019 (n = 1806). Mainly original papers were selected, but also reviews, in English and German language, with a focus on publications in the last 10 years, without excluding older publications that the authors believe are relevant to the topic discussed in the review (n = 40).

Results and Conclusion Ormond’s disease is a rare but important differential diagnosis for nonspecific back and flank pain. Imaging diagnostics using CT or MRI show a retroperitoneal mass, which must be differentiated from lymphoma, sarcoma, multiple myeloma and Erdheim-Chester disease. Patients have an excellent prognosis under adequate therapy. FDG-PET/CT or FDG-PET/MRT should be considered as potential modalities, as hybrid imaging can evaluate both the morphological changes and the inflammation.

Key Points: 

Citation Format

Therapeutic response of immunoglobulin 4-related aortitis and pancreatitis demonstrated by diffusion-weighted MRI

Immunoglobulin (IgG) 4-related disease is a systemic inflammatory disease, and it affects vascular system as aortitis, periaortitis, or aneurysm. However, due to a lack of serum biomarker on aortic damage and the multiorgan involvement, it is difficult to assess aortic inflammatory activity of IgG4-related disease. We described a case of IgG4-related pancreatitis and aortitis, which was visualized with magnetic resonance merged image of diffusion weighted and T₁ weighted images. The aortic signal intensity or apparent diffusion coefficient value reduced or increased after oral prednisone administration, respectively. Magnetic resonance diffusion weighted image and apparent diffusion coefficient may be a useful imaging tool for assessment of vascular inflammation in IgG4-related aortitis.