A two-dimensional (2D) chemical shift correlated MR spectroscopic (COSY) sequence integrated into a new volume localization technique (90°-180°-90°) is proposed for whole-body MR spectroscopy (MRS).Due to the recent improvements in the design of B 0 gradient and RF coils, 1 H MR spectra have been recorded in human brain with excellent water suppression using short TE, as short as 15 ms, and several cerebral metabolites have been identified (1-4). During the past decade alterations in several metabolites, namely, N-acetylaspartate (NAA), glutamate/glutamine (Glx), choline (Ch), creatine (Cr), myo-inositol (mI), and ␥-aminobutyrate (GABA) have been reported in different pathologic states involving the central nervous system (CNS) (5-10). Absolute quantitation of cerebral metabolites in vivo has also been reported for only a few metabolites, albeit with limited success (11-13). Due to severe overlap of these metabolites, an unambiguous assignment of J-coupled metabolite multiplets is severely hindered at 1.5 T field strength.One-dimensional (1D) MR spectral editing techniques to unravel the overlapping resonances rely on J-coupled proton metabolites that have well-separated multiplets. A technique based on subtraction methodology is very sensitive to motion artifacts leading to subtraction errors. An additional drawback is that only one metabolite can be identified at a time. Successful attempts in editing GABA and glutamate using whole-body MRI/MRS scanners have been presented by other researchers (13,14). Single-shotbased multiple-quantum filtered MR spectroscopic sequences have also been implemented on whole-body scanners, but a severe signal loss associated with various coherence transfer pathways made it less attractive to human applications (15)(16)(17).A localized version of a two-dimensional (2D) J-resolved MR spectroscopic (JPRESS) sequence using the PRESS sequence for volume localization was recently proposed (18 -20). Even though the JPRESS sequence retains 100% of the magnetization from a localized volume of interest (VOI), the strong coupling effect inherent at 1.5 T field strength resulted in a complex 2D cross-peak pattern for NAA, glutamate/glutamine, GABA, and other cerebral metabolites (19). Also, some of the 2D cross-peaks were heavily T 2 -weighted during the long incremental delays necessitated by the second dimension of the JPRESS spectrum. An oversampled J-resolved sequence has also been proposed recently (21).Compared to the 2D J-resolved spectra, a COSY spectrum produces a better dispersion of J-cross-peaks, although it requires a larger spectral window to be sampled during the evolution period (22). Different versions of the localized COSY sequence have been implemented by other researchers (23-33). McKinnon and Bosiger (23) proposed a conventional COSY sequence with hard RF pulses (90°-t 1 -90°) followed by three volume selective 180°RF pulses. Haase et al. (24) implemented a COSY combined with an outer volume suppressing sequence, namely, LOCUS. Many previous attempts to develop localiz...

Although computed tomography and magnetic resonance imaging have contributed to the ability to identify metastatic disease in head and neck cancer, inadequacies in evaluating lymphadenopathy still exist. This study was undertaken to estimate the accuracy of radiological criteria used to detect cervical lymph node metastases. The morphological characteristics of 957 lymph nodes from 36 neck dissections from patients with squamous cell cancer were examined microscopically. A large number of malignant nodes were found to have diameters of less than 10 mm. Extranodal spread also occurred in a substantial percentage of smaller nodes. Because the present radiological criteria for assessing cervical lymph node status are based largely on size, findings indicate major limitations in the capabilities of detecting metastatic disease. New modalities to improve the staging of head and neck cancer are discussed.

MR imaging with iron oxide can enable specific differentiation of metastatic and benign nodes in patients with head and neck cancer. This agent may potentially enhance the detection of metastatic lymph nodes and deserves further investigation.

The aim of this study was to define and quantitate the normal anatomy of the extracranial head and neck with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). This information was used to study 12 patients with primary squamous cell carcinomas. In all cases, the lymphoid tissue of the Waldeyer ring and the palatine and lingual tonsils could be differentiated from the airway, striated muscle, osseous structures, and salivary glands. Striated muscle had markedly less activity than lymphoid or salivary gland tissue. In the 12 patients with primary tumors, FDG PET depicted the tumor as an area of increased activity significantly higher than that of normal tissue. In one instance, FDG PET allowed detection of a tumor not seen at magnetic resonance (MR) imaging or computed tomography. Of the 34 lymph nodes positive for carcinoma, 24 were positive according to MR size criteria and 25 were detected with FDG PET. FDG PET allowed detection of three nonenlarged metastatic nodes that were negative at MR imaging.

Background. The purpose of this study was to evaluate the utility of positron emission tomography‐ (PET) 2‐[18F]‐fluoro‐2‐deoxy‐D‐glucose (FDG) imaging in extra‐cranial head and neck cancers. Methods. Sixty patients with biopsy‐proven cancers were studied using PET‐FDG. Thirty‐four patients were studied before therapy (staging), of which 15 patients received primary radiotherapy and serial PET‐FDG imaging (monitoring). Seven patients with advanced disease had laser excision (monitoring), and 19 patients were evaluated for recurrent disease (recurrence). Results. Four patients had unknown primary lesions. PET‐FDG imaging located the primary tumor in two of four patients, and magnetic resonance imaging (MRI) in none of four. In the remaining patients (staging), PET‐FDG imaging detected the primary tumor in 29 of 30 patients, and MRI in 23 of 30. In the staging group, PET‐FDG imaging identified the presence or absence of lymph node involvement in 32 of 34 patients, and MRI in 31 of 34. PET‐FDG imaging was helpful in evaluating tumor response to radiation therapy or laser excision. Ten patients evaluated for recurrent disease had biopsy‐confirmed recurrences, and 7 had no recurrence. PET‐FDG imaging results were positive for primary tumor recurrence in 9 of 10 patients, and MRI results were positive in 6 of 10. MRI results were negative for lymph node disease in one of these patients with recurrent primary tumor where PET‐FDG imaging and biopsy demonstrated nodal involvement. PET‐FDG results were negative for recurrent disease in seven of seven patients, and MRI results were negative for recurrent disease in in four of seven. Conclusion. In this series, the authors found that PET‐FDG is a useful diagnostic modality for evaluating the patient with an unknown primary, monitoring response to therapy, and in detecting recurrent tumors. Cancer 1994; 73:3047–58.