MR imaging of the normal and abnormal clivus

AS. Clival and Paraclival Lesions: A Pictorial Review

The clivus is a midline anatomical structure in the central skull base. It is affected by a wide range of non-neoplastic, benign and malignant pathologies, some of which typically affect the clivus because of its strategic location and embryological origins. Clival lesions may often be asymptomatic with occasional complaints like headache or cranial neuropathy in few. Cross-sectional imaging techniques, namely, computed tomographic scan and magnetic resonance imaging, thus, play a key role in approximating to the final diagnosis and estimating the disease extent. In this article, we highlight the important imaging features of various clival and paraclival pathologies to facilitate effective diagnosis, therapeutic planning, and management.

[Skull base metastases with cranial nerve deficits : Clinical profile of a severe disease]

Hintergrund und Ziele

Schädelbasismetastasen sind eine seltene Manifestation onkologischer Erkrankungen. Wenn Hirnnerven beteiligt sind, können schon kleine Läsionen erhebliche funktionelle Beeinträchtigungen hervorrufen. Spezifische klinische Charakteristika wie neurologische Symptome, assoziierte Primärtumoren, Prognose und optimale Therapie der Erkrankung sind schlecht definiert und sollen in dieser Arbeit systematisch dargestellt werden.

Methoden

Mit einem monozentrischen retrospektiven Ansatz wurden Schädelbasismetastasen bei Patienten, die im Zeitraum von 2006 bis 2018 behandelt wurden, detailliert hinsichtlich klinischer Charakteristika, der durchgeführten Therapie und des weiteren Erkrankungsverlaufs analysiert.

Ergebnisse

Insgesamt 45 Patienten mit Schädelbasismetastasen und Hirnnervenausfällen wurden erfasst. Die häufigsten Primärtumoren waren Prostatakarzinom (27 %), Mammakarzinom (22 %) und multiples Myelom (16 %). Die am häufigsten betroffenen Hirnnerven waren Nervus trigeminus (42 %), Nervus oculomotorius (33 %) und Nervus facialis (27 %). 84 % aller Patienten wiesen außerhalb der Schädelbasis liegende weitere Knochenmetastasen auf. Eine durale Infiltration oder eine Meningeosis neoplastica lagen bei je 13 % der Patienten vor. Nach Bestrahlung waren 61 % der Patienten hinsichtlich der auf die Schädelbasismetastase zurückzuführenden Symptome klinisch stabil, bei 22 % hatten sich die Symptome gebessert. Das mediane Gesamtüberleben betrug 8 Monate (Spanne: 0,4–51 Monate). Bei Patienten, die mit einer dosiseskalierten Bestrahlung behandelt wurden, bestand eine längere Überlebenszeit (16,4 Monate vs. 4,7 Monate). Dieser Effekt persistierte auch in der multivariaten Analyse unter Berücksichtigung der Faktoren Karnofsky-Index, Metastasenanzahl, Primärtumor und Bestrahlungsdosis (HR 0,37, p = 0,02).

Diskussion

Schädelbasismetastasen mit Hirnnervenausfällen haben ein vielgestaltiges Bild und oft eine schlechte Prognose. Um potenziell eine Überlebenszeitverbesserung zu erreichen, sind präzise Diagnostik und Therapie Voraussetzung. Prospektive kontrollierte Untersuchungen sind notwendig.

Agreement on grading of normal clivus using magnetic resonance imaging among radiologists

Purpose

The present study was aimed to evaluate the agreement on grading normal clivus on MRI among radiologists.

Methods

A retrospective study included patients who underwent MRI brain during January 1, 2015 to October 31, 2019. Two hundred forty-four patients who had no marrow pathology on MRI were included and divided into 8 age groups by decades. Three radiologists independently reviewed the signal intensity of clivus in mid sagittal T1-weighted image. The signal intensity was classified into three grades (Grade I-III). Fleiss’ kappa coefficients (k) were calculated to assess interrater agreement.

Results

Of 244 patients, there were 123 (50.4%) males and 121 (49.6%) females. Age ranged from 1 to 79 years old. Clivus Grade II was more frequently reported (> 50%) by radiologists. The agreement (kappa) among all three radiologists on evaluation of clivus irrespective of the grading equals to 0.67 (95%CI: 0.60–0.74). In stratified analyses by the grade of clivus, the kappa values for Grade I to III and were 0.73, 0.62, and 0.69 respectively.

Conclusion

Interrater agreement of MRI evaluation of normal clivus among radiologists was good. The visual grading criteria to classify the clivus is sufficient to distinguish the marrow maturation. However, the consensus reading should be made whenever normal clivus Grade II is read.

Central skull base osteomyelitis manifesting with a preclival mass and internal carotid artery mycotic aneurysm

Central skull base osteomyelitis is a rare entity that can demonstrate confounding radiologic, clinical, and laboratory data leading to a delay in diagnosis. The morbidity and mortality for skull base osteomyelitis are both high, thus a rapid diagnosis is required for appropriate treatment. In this case report, we discuss a 68-year-old male who presented with acute left facial nerve paralysis in the setting of chronic headache and left mucoid middle ear effusion. Radiologic evaluation revealed abnormal hypointense marrow of the central skull base on T1 weighted magnetic resonance imaging, preclival mass-like tissue, and short segment luminal narrowing of the left cervical ICA with mycotic aneurysm formation.

Extensive workup via a multidisciplinary approach, including neurology, otolaryngology, neurosurgery and radiology led to a diagnosis of central skull base osteomyelitis. A familiarity of this disease process is important for the radiologist in order to facilitate appropriate patient referral and treatment. This case emphasizes the importance of considering this diagnosis in the setting of headache, cranial neuropathy, and abnormal skull base imaging with adjacent preclival soft tissue mass.

Metastatic Disease to Clivus: Biopsy or Not?

Due to the aggressive nature of hepatocellular carcinoma (HCC), most patients succumb to disease before any distant metastasis, such as to the central nervous system (CNS), can occur. Thus only a handful of cases of metastasis to the skull base have been described. After a thorough review of the available literature published since 1950, we report the sixth case of HCC metastasis to the clivus. In this case, a 65-year-old man with a history of melanoma presented with sudden onset of right-sided headache and complete ophthalmoplegia of the right eye for one month. MRI of the brain with and without contrast demonstrated a homogeneously enhancing lesion involving the clivus with evidence of invasion into the right cavernous sinus. Through further body imaging, he was found to have an infiltrative lesion in the left hepatic lobe and underwent an ultrasound-guided biopsy of said lesion that was proven to be well-differentiated hepatocellular carcinoma. An endonasal endoscopic biopsy of his clival lesion was performed and the final pathology was consistent with a metastatic HCC. This case demonstrates the impact of obtaining a surgical specimen of clival tumors to confirm the suspected diagnosis, as well as to perform molecular studies that can drive post-operative decision-making and prognosis. As in this case, the final diagnosis altered treatment plans from that of melanoma, with systemic chemotherapy and radiosurgery, to stereotactic radiosurgery and intrahepatic radioembolization.

A slippery slope

A 74-year-old woman experienced chronic painless progressive binocular horizontal diplopia for 2 years. Initial examination showed a visual acuity of 20/20 OU. External and slit lamp examination was unremarkable. Orthoptic evaluation showed an incomitant esotropia, a small vertical strabismus, and a large degree of excyclotorsion. Investigation revealed a diagnosis of diffuse large B-cell lymphoma.

Fossa navicularis in a pediatric patient: anatomical skull base variant with clinical implications

The fossa navicularis is an anatomical variant of the skull base thought to be a rare finding. It represents a bony depression in the skull base. The authors here report the case of a fossa navicularis magna in a 9-year-old female who had been treated for recurrent episodes of meningitis.A literature review was also done to highlight the unique features and clinical importance of this distinctive radiological skull base finding. The literature search covered papers from the 19th century up to 2018. Earlier authors described "fossa navicularis" as a very rare skull base finding. So far, only three cases of fossa navicularis with associated clival or intracranial infection have been reported in the literature. This is the fourth reported case, and the defect was closed endoscopically via a transnasal route. This morphological skull base anomaly should be considered in the differential diagnoses for an unexplained skull base infective pathology.Skull base surgeons should be aware of the existence of the fossa navicularis because of its clinical importance in rendering a prompt diagnosis and appropriate treatment.

Clival metastasis of renal clear cell carcinoma: Case report and literature review

The clivus is an atypical metastatic site for renal clear cell carcinoma (RCCC). Here we report a 54 year old man with acute cavernous sinus syndrome. Brain magnetic resonance imaging identified a clival-based lesion with associated bony erosion. The patient underwent endoscopic endonasal biopsy and partial resection of the clival mass. Because histologic examination of the resected specimen resulted in a diagnosis of RCCC, contrast-enhanced computed tomography scan of the abdomen was performed and showed an enhanced left renal mass. The patient subsequently underwent laparoscopic left radical nephrectomy and gamma knife was planned for the residual clival lesion. We also retrospectively reviewed available published reports on clival metastases, specifically those from RCCC, since 1990.

Isolated clival metastasis: a rare presentation of renal cell carcinoma

Renal cell carcinoma accounts for 3% of all adult malignancies. Usual sites of metastasis are lymph nodes, lungs, bone, liver and brain. We describe a patient who presented with complaints of holocranial headache and diplopia. MRI of the head showed a clival-based lesion with associated bony erosion. With suspicion of a metastatic lesion, an ultrasonogram of the abdomen was done which showed a left renal mass that enhanced on contrast-enhanced CT. There were no other metastatic foci. Patient underwent radiotherapy for the clival lesion. This case report emphasises on the evaluation of clival lesion with cranial neuropathies for a possibility of a renal primary tumour.

Role of diffusion-weighted imaging for detecting bone marrow infiltration in skull in children with acute lymphoblastic leukemia

PURPOSE

We aimed to determine whether diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurement can detect skull bone marrow infiltration in newly diagnosed acute lymphoblastic leukemia (ALL) children before therapy and normalization in complete remission after treatment.

METHODS

Fifty-one newly diagnosed acute lymphoblastic leukemia (ALL) patients and 30 healthy age-matched subjects were included. Cranial magnetic resonance imaging (MRI) scans were reviewed, and skull marrow ADC values were compared before treatment and in complete remission after therapy.

RESULTS

Skull marrow infiltration, manifested with abnormal DWI signals, was present in 37 patients (72.5%) before treatment. Of these, 23 (62.2%) showed scattered signal abnormalities and 14 (37.8%) showed a uniform abnormal signal pattern. Compared with the control group, ADC was significantly decreased in patients with ALL. DWI signal intensity and ADC normalized in patients with complete remission.

CONCLUSION

DWI is a useful and noninvasive tool for detecting skull infiltration in ALL children before treatment and normalization at complete remission after therapy, and it is superior to conventional MRI in terms of conspicuity of these lesions. DWI could be used as an MRI biomarker for evaluation of treatment in ALL children.

Magnetic resonance imaging of the clivus and its age-related changes in the bone marrow

Background

The clivus is a bone region between dorsum cella and foramen magnum. It can be evaluated very clearly in routine brain magnetic resonance imaging (MRI) dueto its central location.

Objectives

Quantitative and qualitative evaluation of the clivus and its changes according to age in a group of healthy people.

Patients and Methods

The transition of clival bone marrow to fatty marrow by the increasein age is examined by MRI in 105 men and 105 women who had no clival and bone marrow pathology on MRI. The clivus/pons, clivus/CSF intensity values and clival bone marrow imaging patterns according to age groups were prospectively evaluated using a 1.5 Tesla MR device.

Results

When age groups were individually compared, there were meaningful statistical differences both in men and women in terms of clivus/CSF and clivus/pons intensity ratios (both Ps < 0.05). Clivus/pons and clivus/CSF intensity ratios were found to be increased with age in all cases. The distribution of age groups according to stages in all individuals was statistically meaningful (P < 0.05). When the appearance patterns of both genders in every ten-fold age were examined, stage III bone marrow was observed more in elder ages.

Conclusions

As a result, besides the fact that standard ranges determined for clivus/CSF, clivus/pons intensity ratios according to age may be used in the assessment of potential pathological cases involving bone marrow; they can also be leading in the diagnosis of bone marrow diseases when taken into consideration together with clinical and laboratory data.

Imaging of Nasopharyngeal Carcinoma

Nasopharyngeal cancer (NPC) is a unique disease that shows clinical behaviour, epidemiology and histopathology that is different from that of other squamous cell carcinomas of the head and neck. Magnetic resonance imaging (MRI) is now the preferred imaging modality in the assessment and staging of NPC, especially in relation to its superior soft tissue contrast, ability to demonstrate perineural tumour spread, parapharyngeal space, bone marrow involvement and its ability to show the involvement of adjacent structures, such as the adjacent paranasal sinuses and intracranial extension. An understanding of its patterns of spread and the criteria used in the AJCC TNM staging system is important to relay the relevant information to the referring clinician, so that appropriate treatment planning decisions may be made. In this article, the various features of NPC that are pertinent to staging and treatment planning will be discussed, inclusive of locoregional spread, nodal involvement and metastatic disease. Key words: Magnetic resonance imaging, Staging

Quality initiatives: blind spots at brain imaging

Radiologists face the daily challenge of analyzing and interpreting a high volume of images in a timely manner. Minimizing errors, whether perceptual or cognitive in nature, is paramount for high-quality diagnostics and patient care. There are certain areas within the head encountered at routine brain imaging in which the interpreting radiologist is most prone to make perceptual errors. These areas, or "blind spots," include the cerebral sulci, dural sinuses, orbits, cavernous sinuses, clivus, Meckel cave, brainstem, skull base, and parapharyngeal soft tissues. In addition, the use of an inappropriate window width and level for the evaluation of computed tomographic (CT) scans can be a virtual, rather than an anatomic, blind spot. The inclusion of a comprehensive checklist for evaluation of these blind spots as part of every brain imaging study is crucial for avoiding false-negative results. Knowledge of the anatomic features of these blind spots is also crucial, as well as familiarity with the normal CT and magnetic resonance imaging findings in these areas. In addition, the radiologist should be aware of possible interpretation pitfalls that may lead to false-positive results (eg, normal anatomic variants that may be mistaken for pathologic conditions). Finally, a well-developed differential diagnosis will help ensure correct interpretation and appropriate patient treatment.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach.Advances in pretherapeutic imaging have significantly contributed to the managementof sinonasal tumors. CT and MR imaging play complementary roles in the assess-mentand staging of these malignancies by determining the presence or absence of exten-sionof disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach. Advances in pretherapeutic imaging have significantly contributed to the management of sinonasal tumors. CT and MR imaging play complementary roles in the assessment and staging of these malignancies by determining the presence or absence of extension of disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Is technetium-99m-MIBI taken up by the normal pituitary gland? A comparison of normal pituitary glands and pituitary adenomas

PURPOSE

The aim of this study was to compare the behavioral uptake of a normal gland and a pituitary adenoma and to assess the ability to diagnose pituitary adenoma by means of technetium-99m-hexakis-2-methoxy-isobutyl-isonitrile (MIBI) single photon emission computed tomography (SPECT).

METHODS

The study included 15 patients with pituitary adenomas (mean age = 44.0 years, range 19-63) and 15 control subjects (mean age = 50.7 years, range 20-67). SPECT was performed 15 minutes after an intravenous injection of MIBI 600 MBq. The shape and location of MIBI uptake were evaluated on a magnetic resonance (MR) imaging/SPECT registration image. The shape patterns and location were classified as follows: Shape C (circular); LO (longitudinal oval); T/R (triangular or rectangular) and location P (pituitary gland or adenoma); D/C (dorsum sellae and/or clivus).

RESULTS

Analysis of the uptake showed that 10 (67%) adenomas were C, and 5 (33%) were LO. Of the controls, 5 (33%) were C, and 10 (69%) were T/R. With regard to location, all patients with pituitary adenomas were classified as P, and all control subjects (93%) but one showed uptake in the dorsum sellae and clivus (D/C).

CONCLUSION

MIBI was taken up in the dorsum sellae or clivus but not the normal pituitary gland and had a strong affinity for the pituitary adenoma. This result implies that MIBI SPECT may be a useful new auxiliary examination technique for the location diagnosis of pituitary adenoma.

Endoscopic transsphenoidal biopsy of the sphenoid and clival mass

Abnormalities of the clivus/skull base occur most commonly as a result of disease spread from adjacent structures, but can also occur from primary involvement of the clivus. Traditionally, definitive diagnosis was made by CT guided biopsy or craniotomy. However, lesions can occur in this area that are not amenable to CT guided biopsy or craniotomy. Endoscopic transsphenoidal surgery can provide a safe method for obtaining a clival biopsy, debulking of tumor tissue, or definitive treatment without the morbidity and mortality of a craniotomy. This study was designed to describe our experience with the endoscopic approach to the skull base and clivus via the sphenoid sinus. A series of seven patients underwent endoscopic transsphenoidal biopsy of a sphenoid clival lesion. All patients avoided anticipated craniotomy, and definitive pathology was obtained in five of six patients. In two cases, excisional biopsy proved to be therapeutic. There were no deaths, and major complications included one CSF leak and one intraoperative hemorrhage, both of which were controlled immediately. The experience gained with these patients demonstrates the feasibility and safety of this new application of endoscopic sinus surgery for the diagnosis and possible treatment of lesions of the sphenoid and clivus.

Assessment of normal clivus related to age with magnetic resonance imaging

The signal intensity pattern cf normal clivus bone marrow related to age was studied on T1-weighted sagittal plain magnetic resonance images. Bone marrow in the clivus had a uniformly low signal intensity (grade 1) in 100% of the patients at 0-5 years and 96% of patients in the first decade (0-9 years). In the second decade there was a sharp decrease in the number of patients (43%) showing grade 1 clivus. Patients having mixed clivus signal intensity (grade 2) were mostly seen in the second decade (28.5%). Uniform high signal intensity (grade 3) was not observed under the age of 10. Grade 3 clivus pattern increased with age from the second decade, while grades 1 and 2 clivus bone marrow showed a marked decrease.

Clivus and cervical spinal osteomyelitis with epidural abscess presenting with multiple cranial neuropathies

A 65-year-old diabetic man with a history of otitis was admitted with headache, neck and shoulder pain and cranial nerve abnormalities including sixth, seventh and twelfth nerve palsies, hearing loss and ptosis. Lumbar puncture revealed an elevated CSF protein and pleocytosis. Imaging procedures demonstrated osteomyelitis of the clivus that involved the epidural space and extended within the prevertebral space to the cervical spine. The patient improved after treatment with antibiotics and immobilization of the neck. This case illustrates the importance of recognizing infections of the clivus in patients with cranial nerve abnormalities.

Normal variation in MRI of the brain

Compared with CT, much more detail and information is seen on any standard MRI sequence. The task of reviewing MRI head scans can therefore be daunting to the new radiologist. This article outlines and emphasizes many of the predictable normal variants, hopefully lessening the burden and preventing the reader from misidentifying many of the common structures.