Single photon emission computed tomography/computed tomography of the skull in malignant otitis externa

Necrotizing external otitis: diagnostic clues in the emergency department

PURPOSE

The assessment of necrotizing external otitis requires a high index of suspicion by the attending physician. The purpose of the study is to determine the accuracy of parameters available at the Emergency Department for the diagnosis of this pathology.

METHODS

Retrospective diagnostic accuracy study. Patients consulting at the Emergency Department for longstanding ear swelling, severe otalgia, and failure to respond to topical treatment were included. Otoscopy, physical examination, CT appearance, and analytical results were tested for the diagnosis of necrotizing external otitis, using nuclear imaging as gold standard. Sensitivity, specificity, likelihood ratios and ROC curves were calculated.

RESULTS

24 patients were included; 13 cases were necrotizing external otitis, and 11 cases were other external ear pathologies. Erythrocyte sedimentation rate and C-reactive protein levels were significantly associated with necrotizing external otitis (AUC 0.92 p < 0.001, and 0.8 p < 0.001). Positive likelihood ratios were 10.15 for values of erythrocyte sedimentation rate over 26 mm/h, and 8.25 for C-reactive protein levels over 10 mg/L. Negative likelihood ratios were 0.08 and 0.28, respectively. These results were significant. The rest of clinical and radiological parameters were less accurate.

CONCLUSIONS

Erythrocyte sedimentation rate and C-reactive protein are useful parameters in the evaluation of a case of longstanding otitis with clinical suspicion of necrotizing external otitis. If any of them is elevated, the probability of suffering this condition is significantly increased. If they are within normal ranges, an alternative diagnosis should be sought.

Incremental Role of 18F-FDG-Labeled Autologous Leukocyte PET/CT in Suspected Postoperative Recurrence of Skull Base Osteomyelitis

ABSTRACT

Skull base osteomyelitis is 1 of the complications of a middle ear infection seen mainly in immunocompromised individuals. A 3-phase bone scan and clinical, laboratory, and other radiological imaging are used for the diagnosis. However, in previously operated cases, bone scan findings are not reliable. We present a case of a 70-year-old man with persistent ear discharge postsurgery and with 3-phase bone scan negative for active infection. However, a subsequent 18F-FDG-labeled autologous leukocyte PET/CT study was able to diagnose the presence of active infection.

Computer tomography findings in necrotizing otitis externa based on the offending pathogens

PURPOSE

High-resolution temporal bone computer tomography (HRTBCT) is the most common initial radiological modality used for the assessment of necrotizing otitis externa (NOE).

OBJECTIVES

(1) To compare the extension of disease, as seen on HRTBCT, in patients with NOE caused by different pathogens and (2) assess whether radiological findings may suggest the offending pathogen in cases of sterile-NOE.

METHODS

All NOE patients were hospitalized between 1990 and 2018. All patients underwent HRTBCT at admission. Three groups (fungus-NOE, PA-NOE and sterile-NOE) comprising of ten patients each were randomly selected. HRTBCT was reevaluated by a senior radiologist. Thirteen radiological subsites were selected for reevaluation.

RESULTS

All patients in the fungal-NOE group complained of otalgia, compared to nine in the sterile-NOE and six in the PA-NOE groups (p value = 0.044). External ear canal edema and granulation tissue were the most common findings in all groups. Surgery was performed in five patients in the fungal-NOE and PA-NOE and three in the sterile-NOE group (p value =  > 0.05). Radiological findings indicating severe bone erosion within the EEC was seen in all patients but 3 (p value =  > 0.05). Severe TMJ erosion was seen in one patient within the fungal-NOE and PA-NOE group (p value =  > 0.05). When mild and severe involvement were combined, TMJ bone erosion was seen in four patients in the fungal-NOE and only in one patient in the PA-NOE (p = 0.04).

CONCLUSIONS

TMJ involvement may be more common in fungal disease, suggesting a different spreading pathway, as opposed to PA-NOE. Accordingly, TMJ involvement on HRTBCT may justify antifungal treatment in sterile culture-NOE.

Imaging in the Diagnosis and Management of Necrotizing Otitis Externa: A Survey of Practice Patterns

OBJECTIVE

To survey neurotologists and head and neck radiologists regarding use of imaging in the diagnosis and management of necrotizing otitis externa (NOE).

STUDY DESIGN

Cross-sectional survey study.

SETTING

Online survey distributed through email to specialty society membership lists.

PARTICIPANTS

Neurotologists and head and neck radiologists with membership in either the American Neurotology Society or The American Society of Head and Neck Radiology.

MAIN OUTCOME MEASURES

Responses to survey consisting of two demographic and seven clinically oriented questions related to the use of imaging in the diagnosis and management of NOE.

RESULTS

One hundred thirty-six participants responded to the survey. The imaging modality of choice in establishing the diagnosis of NOE selected by the respondents was computed tomography (CT) (37.5%) followed by technetium scintigraphy (21.3%). Magnetic resonance imaging (MRI) was the preferred investigation by 41.9% of participants for determining extent of disease. Gallium scanning was the imaging modality preferred by 32.4% of respondents for determining when to cease medical therapy. Ninety-five percent of participants responded that CT scans were always or frequently used in the diagnosis and management of NOE compared with 72.8% for MRI, 34.5% for gallium scans, and 34.2% for technetium scans.

CONCLUSIONS

There is considerable heterogeneity in the preferred imaging modalities used in the diagnosis and management of NOE. CT and MRI are the preferred contemporary modalities used by many physicians, demonstrating a shift away from the historic use of nuclear medicine scans.

Efficacy of HRCT Imaging vs SPECT/CT Scans in the Staging of Malignant External Otitis

OBJECTIVE

The prognosis of patients with malignant external otitis (MEO) depends on the extent of the inflammatory changes in the temporal bone and skull base. The efficacy of high-resolution computed tomography (HRCT) imaging in accurately assessing the extent of disease is compared with that of single-photon emission computed tomography/computed tomography (SPECT/CT) scan.

STUDY DESIGN

A clinical chart review was conducted with medical records and radiologic images.

SETTING

Tertiary care medical college hospital.

SUBJECTS AND METHODS

This study involved patients with clinically diagnosed MEO who underwent both modalities of imaging of the skull base. Staging of the disease extent was compared between the imaging systems among patients. Symptom control and survival rates were analyzed with respect to the SPECT/CT staging of MEO.

RESULTS

Out of 28 patients included in this study, 72% had SPECT/CT scans showing higher staging than the HRCT imaging. Four patients had mild uptake (stage 1), and 15 had disease confined to the mastoid/temporal bone, not reaching midline (stage 2). All patients in stages 1 and 2 were surviving with good symptom control. Five patients with petrous involvement reaching midline (stage 3) had persistent symptoms, and all 4 cases with SPECT/CT showing sphenoid involvement and crossing midline (stage 4) died within a year of diagnosis.

CONCLUSIONS

SPECT/CT scan is more sensitive than HRCT imaging in detecting the extent of disease and is a better prognosticator for patients with MEO.

Additive value of 99mTechnetium methylene diphosphonate hybrid single-photon emission computed tomography/computed tomography in the diagnosis of skull base osteomyelitis in otitis externa patients compared to planar bone scintigraphy

The aim of this study was to evaluate the additive value of ^99mtechnetium methylene diphosphonate (^99mTc-MDP) hybrid single-photon emission computed tomography/computed tomography (SPECT-CT) in the diagnosis of skull base osteomyelitis (SBO) compared to planar bone scintigraphy (PBS). This was a single institution; prospective study included 23 patients with otitis externa, clinically suspected of SBO, all of them were diabetic. Three-phase bone scintigraphy and SPECT/CT were performed to all patients. The imaging modalities which had the most equivocal results were PBS (9/23) followed by SPECT (3/23). No equivocal results were detected with CT or SPECT-CT. SPECT-CT had the highest sensitivity (100%) and highest accuracy (95.7%) in diagnosis of SBO, whereas, PBS showed the lowest sensitivity (50%) and lowest accuracy (52.2%). In this study, SPECT-CT considered the best modality for accurate localization of the site of SBO involvement, followed by CT. SPECT and planar BS were less accurate in this consideration. When comparing the sensitivity of planar BS, CT, SPECT and SPECT/CT, statistical significance difference was detected between planar BS and SPECT (P = 0.057), planar BS and SPECT/CT (P = 0.001), and between CT and SPECT/CT (P = 0.031). No statistically significant difference was detected between SPECT and SPECT/CT (P = 0.250), CT and planar BS (P = 0.125), and between CT and SPECT (P = 0.508) In conclusion, ⁹⁹Tc-MDP SPECT/CT has high sensitivity in the diagnosis of SBO and also provide accurate localization of the site of SBO.

99mTc-HMPAO-leukocyte scintigraphy for diagnosis and therapy monitoring of skull base osteomyelitis

Objective

Skull base osteomyelitis (SBO) is a rare but life‐threatening disease observed in elderly diabetic patients, with high risk of recurrence and difficult therapeutic management. The diagnosis is ascertained from a set of clinical, biological, and imaging findings. CT and MRI allow initial diagnosis, but are not accurate to affirm healing at the end of therapy. 99mTc‐HMPAO‐Leucocyte Scintigraphy (LS) is highly sensitive and specific for the detection of infection. The aim of this study was to evaluate LS i) for initial diagnosis, and ii) to confirm healing at the end of antibiotherapy in SBO.

Study design

We retrospectively reviewed from November 2011 to September 2015 all patients with confirmed SBO who underwent LS twice, at diagnosis and at the end of antibiotic therapy in our nuclear medicine department (n = 27).

Methods

Clinical, biological, CT, LS, and follow‐up data were recorded in all patients. LS images (planar and tomographic performed 4 hours and 24 hours after intravenous injection of autologous Tc‐99m‐HMPAO‐leucocytes) were visually assessed and quantified.

Results

At initial diagnosis, 25 of 27 patients had a positive LS. At the end of antibiotic therapy (3 ± 1 months duration), 26 of 27 patients had a negative LS. During subsequent follow‐up (= or >6 months), the disease recurred in four patients including three with a negative postantibiotherapy LS scan.

Conclusion

In this retrospective study, LS was powerful for initial diagnostic of SBO and for healing assessment at the end of antibiotic therapy. We conclude it is a useful technique for therapeutic monitoring of SBO.

Level of Evidence

4

Advanced Imaging Techniques in Skull Base Osteomyelitis Due to Malignant Otitis Externa

PURPOSE OF REVIEW

To give an up-to-date overview of the strengths and weaknesses of current imaging modalities in diagnosis and follow-up of skull base osteomyelitis (SBO).

RECENT FINDINGS

CT and MRI are both used for anatomical imaging, and nuclear techniques aid in functional process imaging. Hybrid techniques PET-CT and PET-MRI are the newest modalities which combine imaging strengths.

SUMMARY

No single modality is able to address the scope of SBO. A combination of functional and anatomical imaging is needed, in the case of newly suspected SBO we suggest the use of PET-MRI (T1, T2, T1-FS-GADO, DWI) and separate HRCT for diagnosis and follow-up.

[Techniques and progress in the imaging of the ear]

Ear and temporal bone imaging is essential for the diagnostic and preoperative management of middle ear lesions. The scanner is the exam of choice to analyze the walls and the contents of the middle ear. MRI is used to characterize the opacities of the middle ear and to evaluate possible neurological complications. Modern imaging techniques allow intraoperative guidance in otological surgery. Hearing implants are not always a contraindication to MRI but require precautions according to the type of implant.

Skull base osteomyelitis in otitis externa: The utility of triphasic and single photon emission computed tomography/computed tomography bone scintigraphy

Background:

Skull base osteomyelitis (SBO) refers to infection that has spread beyond the external auditory canal to the base of the skull in advanced stages of otitis externa. Clinically, it may be difficult to differentiate SBO from severe otitis externa without bony involvement. This study was performed to determine the role of three phase bone scintigraphy (TPBS) and single photon emission tomography/computed tomography (SPECT/CT) in detecting SBO.

Materials and Methods:

We retrospectively analyzed records of 20 patients (14 M, 6 F) with otitis externa and suspected SBO. TPBS and SPECT/CT of the skull were performed. Findings were correlated with clinical, laboratory and diagnostic CT scan findings.

Results:

All patients were diabetic with elevated erythrocyte sedimentation rate. A total of 18 patients had bilateral and two unilateral symptoms. Cranial nerves were involved in eight patients and microbiological culture of ear discharge fluid positive in seven. Early images showed increased temporal vascularity in nine patients and increased soft-tissue uptake in 10, while delayed images showed increased bone uptake in 19/20 patients. Localized abnormal tracer uptake was shown by SPECT/CT in the mastoid temporal (15), petrous (11), sphenoid (3) and zygomatic (1) and showed destructive changes in five. Thus, TPBS was found positive for SBO in 10/20 patients and changed the management in four.

Conclusion:

Our study suggests that TPBS with SPECT/CT is a useful non-invasive investigation for detection of SBO in otitis externa.

Utility of (99m)Tc-MDP hybrid SPECT-CT for diagnosis of skull base osteomyelitis: comparison with planar bone scintigraphy, SPECT, and CT

PURPOSE

To evaluate single photon emission tomography-computed tomography (SPECT-CT) for diagnosis of skull base osteomyelitis (SBO) and to compare this technique with planar bone scintigraphy (BS), SPECT, and CT.

METHODS

Data from 13 patients with known/suspected SBO were retrospectively analysed. Planar BS and SPECT images were evaluated by an experienced nuclear medicine physician, CT by and experienced radiologist, and SPECT-CT by the nuclear medicine physician and radiologist in consensus. On the basis of diagnostic confidence a score of 1-5 was given, with 1 being definitely osteomyelitis, 2 being probably osteomyelitis, 3 being equivocal, 4 being probably normal, and 5 being definitely normal. ROC analysis areas under the curves (AUC) were calculated. For diagnostic values a score of ≤2 was taken as positive. Clinical/imaging follow-up/microbiology was taken as reference standard.

RESULTS

AUC was largest for SPECT-CT (0.977) followed by SPECT (0.909), CT (0.886), and planar BS (0.614). However, no significant difference was found between the techniques except for borderline significance between planar BS with SPECT-CT (P = 0.071) and CT (P = 0.072). Accuracy was 46% for planar BS, 85% for SPECT, 77% for CT and 92% for SPECT-CT.

CONCLUSION

SPECT-CT seems to be useful, but not superior to planar BS, SPECT, or CT, for diagnosis of SBO.