Chondro-osseous border in baby hip ultrasonography for developmental dysplasia of the hip: an indispensable litmus paper for the accuracy of scientific publications

PURPOSE

The aim of our study was to use the chondro-osseous border (COB) as an indispensable assessment criterion to evaluate the quality of baby hip ultrasonography (US) images in the literature pertaining to the application of Graf's technique.

MATERIALS AND METHODS

Our literature review search yielded 144 articles. Of these, 41 contained images that were stated to be based on the application of Graf's technique. Two reviewers, a radiologist and an orthopaedic surgeon, both course instructors for the use of baby hip US for developmental dysplasia of the hip (DDH), independently evaluated the articles to assess the diagnostic validity of the published images on the basis of a single criterion: the identification of the COB.

RESULTS

Of the 41 articles which were analyzed, 15 contained images without a COB, which corresponds to 36% (roughly, one out of three). Articles from countries where universal screening is performed (Germany, Italy, Switzerland, Mongolia) were all correct. All the articles from Turkey, a country which has made significant contribution with published material about Graf's technique over many years, and most of the articles from China (80%), where Graf's technique has become popular in recent years, contained correct images.

CONCLUSION

Published literature lacks strict criteria for the publication of correct images corresponding to Graf's technique in baby hip US. This fact raises concerns about the quality of published material (and, as a corollary, the quality of clinical application of the technique) and should have ramifications on scientific journal policies regarding the publication of such manuscripts.

Determinants of in-hospital muscle loss in acute ischemic stroke - Results of the Muscle Assessment in Stroke Study (MASS)

BACKGROUND & AIMS

There is a change in the mass and composition of paretic and non-paretic skeletal muscles in the chronic phase of stroke. The multi-center, prospective, and observational Muscle Assessment in Stroke Study (MASS) was performed to evaluate the degree of muscle loss during the in-hospital acute stroke setting and determine factors contributing to this loss.

METHODS

Acute dysphagic ischemic stroke patients (n = 107) admitted to neuro-intensive care units were evaluated by computed tomography on days 1 and 14 after admission to determine the cross-sectional muscle area (CSMA) at the level of the mid-humerus, mid-thigh, and third lumbar vertebra. The percentage change in CSMA and variables associated with this change were evaluated by univariate and multivariate analyses.

RESULTS

There were significant reductions in CSMA in all the muscle groups analyzed; the most prominent change was observed in the arms (both: 14.2 ± 10.7%; paretic: 17.7 ± 11.6%; non-paretic: 10.1 ± 12.5%), followed by the muscles in the legs (both: 12.4 ± 8.7%; paretic: 12.9 ± 9.9%; non-paretic: 12.0 ± 9.3%) and L3-vertebra level (5.6 ± 9.8%) (P < 0.001 for all). Higher calorie (r = -0.378, P < 0.001) or protein (r = -0.352, P < 0.001) intake was negatively associated with the decrease in CSMA of upper extremities. A substantial protein (≥0.4 g/kg/d) or calorie (≥5 kcal/kg/d) gap between targeted or actual intake was related to a larger decrease in CSMA in all the anatomic regions (P ≤ 0.05 for all). Other significant predictors of muscle loss included history of diabetes mellitus, male sex, higher BMI, in-hospital infections, and the necessity for invasive mechanical ventilation.

CONCLUSIONS

There is a considerable degree of loss in the global muscle mass in acute ischemic stroke patients over a two-week period. Along with several factors, falling significantly behind the daily protein or calorie targets was related to the decrease in the muscle area. TRIAL REGISTRATION INFORMATION: clinicaltrials.gov identifier NCT03825419.

Imaging Osteomyelitis: An Update

BACKGROUND

 Hematogenous osteomyelitis has increased over the past quarter century in frequency, virulence, and degree of soft-tissue involvement, bringing about changes in clinical manifestations and management of the disease especially in children that should be reflected in the current imaging approach. Likewise, the global disease burden of diabetes has increased greatly in the same period, compounding the problem of ascertaining osteomyelitis in diabetic foot.

METHOD

 This article provides an updated overview of imaging findings in hematogenous and contiguous osteomyelitis based on the literature and our institutional experience, along with salient features of recent recommendations from expert groups on the diagnostic algorithms and reporting terminology.

RESULTS AND CONCLUSION

 Findings on radiography and especially magnetic resonance imaging (MRI) closely reflect pathophysiology in osteomyelitis, whereby the characteristic involvement of the metaphysis or metaphyseal-equivalents, the formation and subperiosteal extension of intramedullary pus collection, and the development of cloaca, sequestrum, and involucrum are all diagnostic clues. Non-enhancing foci within the medullary bone, the penumbra sign, intra- or extramedullary fat globules, and surrounding soft tissue inflammation or abscesses are among key MRI findings. Diabetic foot is a special condition with characteristic pathophysiologic and imaging features that suggest the likelihood of osteomyelitis and the main differential diagnostic consideration of acute on chronic neuropathic osteoarthropathy with or without osteomyelitis.

KEY POINTS

  · Imaging closely reflects pathophysiology in hematogenous osteomyelitis.. · Acute hematogenous osteomyelitis predominantly involves metaphyses and metaphyseal equivalent sites.. · MRI clues for hematogenous osteomyelitis include central marrow non-enhancement, intra- or extramedullary fat globules, and the "penumbra" sign.. · An increased fluid-sensitive MRI bone signal abutting a soft tissue ulcer, abscess, or sinus tract suggests a high probability of contact osteomyelitis..

CITATION FORMAT

· Aydingoz U, Imaging Osteomyelitis: An Update. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1949-7641.

A Child with Refractory and Relapsing Anti-3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Myopathy: Case-Based Review

BACKGROUND/OBJECTIVE

Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) myopathy is rare in children. Here, we present a boy with relapsing refractory anti-HMGCR myopathy along with a systematic literature review.

CASE REPORT

17-year-old boy with five years of muscle weakness, rash, high creatinine kinase (CK) levels, and muscle biopsy compatible with inflammatory myopathy was diagnosed with juvenile dermatomyositis. He was treated with corticosteroids, intravenous immunoglobulin (IVIG), and methotrexate. His muscle weakness improved with this treatment although never completely resolved. CK levels decreased from ∼15000 U/L to ∼3000 U/L. At the age of 15, muscle weakness relapsed after an upper respiratory tract infection; pulse corticosteroid treatment was administered. The re-evaluated muscle biopsy showed a necrotizing pattern and the HMGCR antibody was positive confirming anti-HMGCR myopathy when he was 16. The diagnostic delay was 50 months. Disease activity was monitored by Medical Research Council score, MRI and functional tests. Despite corticosteroids, methotrexate, IVIG, cyclosporine A, and rituximab therapies, muscle weakness improved only slightly during the first three months and remained stable afterwards.Results of the Literature Search:We identified 16 articles describing 50 children (76% female) with anti-HMGCR myopathy by reviewing the English literature up to March 1st, 2022. Proximal muscle weakness was the most common clinical symptom (70.8%). Corticosteroids (84.8%), IVIG (58.7%), and methotrexate (56.5%) were preferred in most cases. Complete remission was achieved in nine patients (28.1%).

CONCLUSION

Diagnosis and management of children with anti-HMGCR myopathy are challenging. Complete remission is achieved in only one third of these patients. Imaging biomarkers may aid treatment.

Sclerosing epithelioid fibrosarcoma of bone: morphological, immunophenotypical, and molecular findings of 9 cases

Primary sclerosing epithelioid fibrosarcoma (SEF) of bone is a rare and scarcely reported neoplasm. We document clinicopathological and molecular features of 9 additional cases. Five males and 4 females had a mean age of 39 years (14-71 years). Most tumors affected flat/irregular bones; only 3 cases involved a long bone. By radiology, it has characteristic radiographic features of a predominantly lytic expansile lesion with a sclerotic rim. Referring diagnoses were SEF (n = 2), low-grade osteosarcoma (n = 2), chondrosarcoma (n = 1), and chondromyxoid fibroma (n = 1). Histologically, five cases revealed classical morphology of SEF of soft tissue. Remaining cases were classified as hybrid SEF/low-grade fibromyxoid sarcoma, characterized by spindle or stellate cells, prominent stroma, and giant hyalinized areas. Various morphological deviations such as prominent vasculature (n = 3), osteoid-like material (n = 4), or parallel bone trabeculae (n = 2) were observed. Immunohistochemically, all cases showed diffuse and strong MUC4 expression. SATB2 was observed in 5/8 cases. Using FISH, EWSR1, and FUS rearrangements were detected in 4 cases and 1 case, respectively. EWSR1-CREB3L1 fusion was identified in 1 additional case by next-generation sequencing. Recurrence and metastasis were observed in 1 case and 2 cases, respectively. All but one patient were alive with disease for a mean interval of 31 months. SEF of bone is a relatively indolent sarcoma of adults, most commonly located in the flat/irregular bones. Due to overlapping histological features, it is often misdiagnosed as osteosarcoma or a chondroid tumor. Most SEF of bone exhibit EWSR1 rearrangements, but rare cases may harbor a FUS gene fusion.

International Interdisciplinary Consensus Meeting on the Evaluation of Developmental Dysplasia of the Hip

In September 2018, an international meeting of doctors of various disciplines, with expertise in the detection and treatment of DDH, was held in Csolyospalos, Hungary. The aim was to achieve consensus on the detection and early treatment of the condition and to develop a standardized system of teaching and training for hip ultrasound. There was strong agreement that US screening is essential. Specifically the Graf technique was selected as the technique of choice. Universal US screening was strongly favored. Screening should be carried out as soon as possible, but not later than the sixth week of age. US screening is cost-effective, does not result in overtreatment, and contributes to a reduction of long-term consequences. The essential principle of treatment is timely application of a device to achieve reduction, retention and maturation, by holding the hips in flexion, and a safe degree of abduction. It was agreed that the effectiveness of any screening policy depends on the correct scanning technique. Therefore, standardization of teaching and training of the Graf technique is mandatory. A unified teaching policy and materials should be developed for this purpose. Certification, re-certification and audit were discussed. The group, which has been formalized as the International Interdisciplinary Consensus Committee On DDH Evaluation (ICODE), will continue to meet and work towards establishing international consensus on DDH, standardizing and developing teaching and training of the Graf technique for hip US, and maintaining standards for detection and management.

Magnetic Resonance Imaging (MRI) of Snapping Scapula in a 10-Year-Old Boy

Background

Snapping scapula syndrome, also known as scapulothoracic crepitus or bursitis, is a manifestation of a mechanical abnormality of the scapulothoracic joint. In addition to characteristic findings on physical examination, magnetic resonance imaging (MRI) exquisitely reveals soft tissue changes such as muscle edema and scapulothoracic bursitis.

Case Report

We present a case of a 10-year-old boy who had snapping scapula syndrome of the right scapula that was associated with edema of the serratus anterior muscle at the scapulothoracic interface and with scapulothoracic, specifically supraserratus, bursitis on MRI.

Conclusions

MRI in snapping scapula syndrome, which is a clinical diagnosis, exquisitely reveals soft tissue changes such as muscle edema and scapulothoracic bursitis. Such soft tissue findings of snapping scapula syndrome need to be kept in mind while evaluating routine shoulder and/or scapular region MRI, especially in the absence of relevant clinical information at the time of the imaging study.

Recessive PIEZO2 stop mutation causes distal arthrogryposis with distal muscle weakness, scoliosis and proprioception defects

The genetic work-up of arthrogryposis is challenging due to the diverse clinical and molecular etiologies. We report a-18^3/12-year-old boy, from a 2nd degree consanguineous family, who presented at 3^6/12 years with hypotonia, distal laxity, contractures, feeding difficulties at birth. He required surgery for progressive scoliosis at 16 years of age, and walked independently since then with an unstable gait and coordination defects. His latest examination at 18 years of age revealed a proprioceptive defect and loss-of-joint position sense in the upper limbs. Somatosensory evoked potentials supported bilateral involvement of dorsal column-medial lemniscal sensory pathways and nerve conduction studies revealed a mild axonal neuropathy. Muscle biopsy showed myopathic changes with neonatal myosin expression. Mendeliome sequencing led to the discovery of a recessive stop mutation in piezo-type mechanosensitive ion channel component 2 (PIEZO2, NM_022068, c.1384C>T, p.R462*). PIEZO2 is a nonselective cation channel, expressed in sensory endings of proprioceptors innervating muscle spindles and Golgi tendon organs. Dominant PIEZO2 mutations were described in patients with distal arthrogryposis type 5 and Marden-Walker syndrome. Sensory ataxia and proprioception defect with dorsal column involvement together with arthrogryposis, myopathy, scoliosis and progressive respiratory failure may represent a distinct clinical phenotype, and indicate recessive mutations in PIEZO2.

Intraosseous pseudotumor in a child with hypofibrinogenemia

Intraosseous pseudotumor (i.e. chronic, encapsulated, hemorrhagic fluid collection that can be seen in any portion of the tubular bones) is an uncommon complication of severe hemophilia; however, it can occur with other rare bleeding disorders. We present the case of an 11-year-old girl with hypofibrinogenemia who had multiple intramedullary lesions that were consistent with intramedullary pseudotumor associated with this rare bleeding disorder. Percutaneous biopsy of a pseudotumor is contraindicated due to the high prevalence of complications, including life-threatening bleeding. Therefore, radiologists should make the diagnosis with characteristic MR imaging findings in a patient with a severe coagulation disorder.

A critical overview of the imaging arm of the ASAS criteria for diagnosing axial spondyloarthritis: what the radiologist should know

The Assessment in SpondyloArthritis international Society (ASAS) defined new criteria in 2009 for the classification of axial spondyloarthritis (SpA) in patients with ≥ 3 months of back pain who were aged <45 years at the onset of back pain. This represents a culmination of a number of efforts in the last 30 years starting with the 1984 modified New York criteria for ankylosing spondylitis, followed by the 1990 Amor criteria and the 1991 European Spondyloarthropathy Study Group criteria for SpA. The importance of new ASAS criteria for radiologists is that magnetic resonance imaging (MRI) takes center stage and is one of the major criteria for the diagnosis of axial SpA when active (or acute) inflammation is present on MRI that is highly suggestive of sacroiliitis associated with SpA. According to the new criteria, sacroiliitis on imaging plus ≥ 1 SpA features (such as inflammatory back pain, arthritis, heel enthesitis, uveitis, dactylitis, psoriasis, Crohn's disease/colitis, good response to non-steroidal anti-inflammatory drugs, family history for SpA, HLA-B27 positivity, or elevated C-reactive protein) is sufficient to make the diagnosis of axial SpA. A number of rules and pitfalls, however, are present in the diagnosis of active sacroiliitis on MRI. These points are highlighted in this review, and a potential shortcoming of the imaging arm of the ASAS criteria is addressed.

MRI of a benign chondroid syringoma

Chondroid syringoma, also known as mixed tumour of the skin, is a relatively rare, usually benign tumour. A few malignant cases, especially in the lower extremities, have been published, but most of them behave in a benign fashion. A case of a middle-aged woman with surgically proved chondroid syringoma in the pretibial region is presented in this report with MRI and histological findings. Despite rapid growth over a short period of time and a location reportedly associated with malignancy, the histological features were benign.

Does Dega osteotomy increase acetabular volume in developmental dysplasia of the hip?

Whether acetabular volume increases or decreases after acetabular Dega osteotomy is not known. The purpose of this study is to determine the effect of Dega osteotomy on the volume of the acetabulum in patients with developmental dysplasia of the hip. Nine hips of seven patients with developmental dysplasia of the hip that have undergone Dega osteotomy were included in the study. The acetabular index, acetabular depth, and acetabular volume of each hip were calculated before and after surgery. Magnetic resonance imaging was used for the measurement of the acetabular volume. The difference between the preoperative and postoperative values of acetabular index, acetabular depth, and acetabular volume was statistically significant. We conclude that Dega acetabular osteotomy increases the volume of the acetabulum.

The effect of pedicle screw placement with or without application of compression across the neurocentral cartilage on the morphology of the spinal canal and pedicle in immature pigs

STUDY DESIGN

Experimental study.

OBJECTIVES

To investigate the effects of pedicle screw insertion on spinal canal and pedicle morphology in immature pigs, and, if transpedicular fixation has an effect, to document whether this occurs because of the inhabitance of the screw inside the growth plate (neurocentral cartilage [NCC]) or because of compression applied across the NCC.

SUMMARY OF BACKGROUND DATA

Transpedicular fixation has been less commonly applied to the pediatric population, especially because of the risk of damage to the NCC.

METHODS

Twelve newborn pigs (4-6 weeks of age) were operated on. Left sided pedicles from L1-L5 were studied, while right sides served as controls. Pigs were randomly assigned into 3 groups: (1) pedicles were probed only; (2) screws were inserted; and (3) after screw insertion, a washer and a nut were engaged at the pedicle entry point so that gradual compression across the NCC was achieved. After 4 months, spiral computerized tomography was used to measure the pedicle lengths and size of the halves of the spinal canal.

RESULTS

In group 1, the operated hemi-canal area was not statistically different from the nonoperated side (P = 0.159). Pedicle screw insertion either with (P = 0.007) or without (P = 0.005) compression resulted in smaller hemi-canal area and shorter pedicles at the operated side, respectively (P = 0.008, P = 0.021). Approximately 4% to 9% shortening of the pedicle lengths and 20% to 26% narrowing of the hemi-canal areas on the instrumented side occurred with transpedicular instrumentation (groups 2, 3).

CONCLUSION

Even without compression, pedicle screws passing through the NCC in immature pigs disturb spinal canal growth significantly. Clinical relevance for young children should be studied further.

???Black??? Contrast Effect During Magnetic Resonance Arthrography Attributable to Inadvertent Administration of Excessive Gadolinium Chelates

Excessive intra-articular administration of gadolinium chelates during magnetic resonance (MR) arthrography results in decreased signal throughout the joint on MR images. A case with this condition during MR arthrography of the hip is described, and a possible solution when this problem occurs (ie, performing the MR imaging examination after a waiting period of several hours) is suggested.

Vascular malformation in the infrapatellar (Hoffa's) fat pad

A 16-year-old girl presented with pain and swelling of her right knee for 2 years. Magnetic resonance imaging disclosed a mass in the infrapatellar fat pad. Arthroscopic removal of the lesion led to a histopathologic diagnosis of vascular malformation, which has not been reported exclusively in this location.

Combination of Extremity Computed Tomography Angiography and Abdominal Imaging in Patients With Musculoskeletal Tumors

PURPOSE

To introduce a comprehensive computed tomography (CT) protocol for the evaluation of patients with musculoskeletal tumors by combining extremity CT angiography and abdomen CT in a dynamic multidetector CT study.

METHODS

Single contrast bolus was used for each study in 4 patients with musculoskeletal tumors involving the lower extremities. Extremity CT angiography and abdominal CT were acquired sequentially by 4-channel multidetector CT. Technical parameters for extremity CT angiography were as follows: detector collimation, 4 mm x 1 mm; pitch, 1.75; slice thickness, 1.25 mm; reconstruction interval, 1 mm; coverage, 42 cm; and table speed, 14 mm/s. Thick and thin maximum intensity projections, volume renderings, and multiplanar reformats with or without bone subtraction were used to display vascular supply of the extremity mass and adjacent vascular structures.

RESULTS

Satisfactory images of the extremity arterial system and abdomen were obtained in all patients. The mean delay time for CT angiography was 25 seconds. Extremity CT angiography demonstrated feeding arteries of a fibular giant cell tumor and a large lymphomatous mass. The same protocol was used for the evaluation of a distal tibial osteosarcoma and a fibular chondrosarcoma. In 2 patients, early venous return was noted, indicating vascularity of the tumors. In all patients, the relation of osseus masses to adjacent vascular structures was visualized as well as the bony anatomy.

CONCLUSION

Extremity CT angiography and abdominal staging CT can be combined in a single dynamic multidetector CT protocol in patients with musculoskeletal tumors, resulting in a reduction of costs, acquisition time, and contrast dose as well as an improvement in patient management. The same protocol can also be used in trauma patients.

The Deep Infrapatellar Bursa

OBJECTIVE

To evaluate the presence, location, and dimensions of the deep infrapatellar bursa on routine magnetic resonance (MR) imaging of the knee.

METHODS

The study group consisted of 213 knees in 204 consecutive individuals who had undergone routine MR imaging examination of the knee within a 365-day period. Magnetic resonance examinations consisted of T1-, proton-density-, and T2-weighted sagittal; spectral presaturation inversion recovery coronal; and T2*-weighted transverse sequences. Exclusion criteria were previous knee arthroscopy or surgery or the presence of a mass lesion infiltrating the infrapatellar fat pad. The presence, location, and dimensions of the deep infrapatellar bursa were studied. The bursa was also analyzed with regard to knee joint synovial effusion (absent, mild, or marked).

RESULTS

The deep infrapatellar bursa was detected in 68% of the knees, most commonly on the lateral paramedian sagittal MR images. There was no statistically significant difference between male and female subjects or between the knee sides with regard to the detection of the deep infrapatellar bursa (P > 0.05). No correlation was found between synovial effusion and the presence of the deep infrapatellar bursa. The mean anteroposterior and craniocaudal dimensions of the deep infrapatellar bursa on sagittal T2-weighted MR images were 2.1-2.7 mm and 7.3-9.1 mm, respectively, on its lateral, central, or medial location within the sagittal MR image stack.

CONCLUSION

An awareness of the dimensions and location of the deep infrapatellar bursa is important in distinguishing it from pathologic lesions (eg, bursitis).

Magnetic resonance imaging determination of the ventriculus terminalis

We report a case of ventriculus terminalis, presenting with specific neurological symptoms including low back pain and bilateral sciatica. Magnetic resonance images showed a cystic lesion with regular margins localized in the lumbar enlargement of the spinal cord. The lesion was an oval shape with no internal septa. Its dimensions were 9.6 mm craniocaudally, 3.5 mm mediolaterally and 3.5 mm anteroposteriorly. Intralesional fluid had the same signal as cerebrospinal fluid in all magnetic resonance sequences. Pericystic spinal cord intensity was normal, and the cyst did not cause additional enlargement of the distal cord. During spinal cord evaluations, ventriculus terminalis should be kept in mind as a normal anatomic developmental phenomenon that can be seen on magnetic resonance images.

Water-lily sign on MR imaging of primary intramuscular hydatidosis of sartorius muscle

Primary hydatidosis of muscle is very rare and can cause a variety of diagnostic problems, especially in the absence of typical radiologic findings. This is the report of a case of primary intramuscular hydatid cyst in a 35-year-old woman, who presented with a 1-year history of a painless lump in the distal left thigh. The authors document the pathognomonic water-lily sign that has not previously been reported in a case of intramuscular hydatid disease.

Cerebellar and basal ganglion involvement in Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a disease of unknown cause characterised by proliferation of histiocytic granulomas in tissues; the primary cerebral manifestation is diabetes insipidus caused by hypothalamic infiltration. We present a patient in whom, except for the absence of high signal on T1 weighting in the posterior pituitary, consistent with central diabetes insipidus, MRI showed no evidence of hypothalamic involvement by histiocytosis, despite the long duration of the disease. However, there was bilateral, symmetrical involvement of the cerebellum and globus pallidus in addition to a calvarial lesion. High signal in the cerebellar white matter on T2-weighted images may represent demyelination, gliosis and cell loss, as previously reported on pathologic examination.

MR imaging in squamous cell carcinoma of the head and neck with no palpable lymph nodes

PURPOSE

To assess the efficacy of MR imaging in the detection of lymph node metastasis in patients with no palpable lymph nodes ("N0 neck") who have squamous cell carcinoma of the head and neck region.

MATERIAL AND METHODS

MR neck imagings in 18 patients who underwent neck dissection (bilaterally in 2) for squamous cell carcinoma of the head and neck region were examined preoperatively for the purpose of detecting lymph node metastases. The imaging features taken into consideration were: size (cutoff point 10 mm), grouping, presence of central necrosis, and appearance of extracapsular spread. The MR examinations comprised spin-echo T1- and T2-weighted sequences. The MR findings were compared with those of surgery and histopathological examination.

RESULTS

MR suggested metastatic lymph node involvement in 5 necks. In 2 of these, central necrosis was seen in the enlarged lymph nodes. In a third, a grouping of the lymph nodes was noted. Extracapsular spread was not present. Histopathological examination revealed metastatic lymph nodes in 7 of the 20 necks, the rate of clinically occult disease being 35%, and 4 of them had been accurately graded by MR. There was one false-positive MR examination. The MR sensitivity was 57.1% and specificity 92.3%.

CONCLUSION

MR may reveal metastatic lymph nodes in patients with no clinical evidence of metastasis. However, conventional MR techniques are not always sufficient for decision-making on surgery in cases of "N0 neck".