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NEURORADIOLOGY HEAD AND NECK IMAGING Table of Contents   
Year : 2002  |  Volume : 12  |  Issue : 2  |  Page : 189-195
Distinguishing neoplastic and non-neoplastic ring enhancing lesions of the brain detected in CT and/or MRI with the help of correlative nuclear imaging


EKO X-ray & Imaging Institute, 54, Jawaharlal Nehru Road, Calcutta-700071, India

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   Abstract 

Objectives: To distinguish between neoplastic and non-neoplastic lesions showing ring enhancement or ring like lesions in the brain in CT or MRI with the help of correlative Nuclear imaging. Material and Methods: Twenty seven patients with various ring enhancing lesions in the brain detected in CT and/ or MRI were correlated with cerebral first pass study, Planar and SPECT imaging using different radiotracers like 99m Tc-HMPAO. TI-201, 99m Tc-DTPA/GHA, 99m mTc-MIBI or Tetrofosmin Results: Nuclear scanning was helpful in distinguishing between neoplastic and non-neoplastic conditions in 42 percent of cases in this study where C T or MRI were doubtful. Conclusion: Nuclear imaging coupled with CT or MRI provides a fairly accurate diagnosis in differentiating neoplastic conditions from non-neoplastic conditions without any MR Spectroscopic or Sterotactic biopsy technique applied on the patients.

Keywords: Ring enhancing lesions, brain SPECT and Quantification

How to cite this article:
Ray S, Kundu B, Kundu S, Roy S, Sharma S K. Distinguishing neoplastic and non-neoplastic ring enhancing lesions of the brain detected in CT and/or MRI with the help of correlative nuclear imaging. Indian J Radiol Imaging 2002;12:189-95

How to cite this URL:
Ray S, Kundu B, Kundu S, Roy S, Sharma S K. Distinguishing neoplastic and non-neoplastic ring enhancing lesions of the brain detected in CT and/or MRI with the help of correlative nuclear imaging. Indian J Radiol Imaging [serial online] 2002 [cited 2019 Nov 22];12:189-95. Available from: http://www.ijri.org/text.asp?2002/12/2/189/28441

   Introduction Top


Ring enhancing lesions in CT and MRI of the brain can be caused by different pathological conditions. The common lesions being some primary brain tumours, abscess, granuloma, resolving haematoma and infarct. Less common conditions being thrombosed vascular malformation and demyelinating disease such as Multiple Sclerosis. Uncommon causes being thrombosed aneurysm and other primary brain tumours such as primary CNS lymphoma in AIDS etc. [1] With this large list of conditions contributing to intracranial ring enhancing lesions one has to assess the patient clinically as well as distinguish between neoplastic and non-neoplastic nature of the lesion as detected in CT and / or MRI.

The aim of this study is to distinguish between neoplastic and non-neoplastic condition in ring enhancing lesions of the brain as seen in CT and or MRI with the help of Nuclear imaging and quantification.


   Material and Methods Top


A total of 27 patients with various ring enhancing lesions in the brain detected by CT and or MRI were included in this correlative study with Nuclear Medicine. 17 male and 10 female patients were studied in between July, 1998 to December, 1999. The mean age of the patients were 9 to 78 years. All the patients were subjected to CT (GE - Prospeed SX - Advantage spiral scanning) and MRI (Siemens - 1 Tesla superconducting) scan studies of the brain mostly contrast enhanced except for in the case of MRI where one patient refused application of I.V. Contrast. Non-ionic iodinated contrast - (lohexol - Omnipaque 350 mg. - 20 cc.) was used for CT and Gadodiamide (Gd - DTPA-BMA - 10 cc - OMNISCAN) were given for MRI studies. Routine sequences of T1, T2 and proton density spin echo sequences were carried out.

All the patients were then subjected to Nuclear imaging by a Gamma Camera (Siemens Diacom SPECT System) which included cerebral first pass study (CBF), planar and SPECT images obtained using different radiotracers like 99m Tc - HMPAO, TI - 201, 99m Tc-DTPA / GHA etc.

Intravenous injections of the radiotracer were given to the patients. Then the entire information was tabulated and quantitative studies of the lesions were done by Nuclear imaging methods.

Computerised quantification of the regional radiotracer uptake in the lesions were performed. Symmetric ROIs (Region of interest) were drawn around the lesions. Mirror ROIs of same size were placed on the similar area of the opposite cerebral hemispheres. Reference background ROIs are also placed on normal regions. Lesion to non-lesion ratios were calculated from the above mentioned ROIs after pixel normalization. In another method each cerebral hemispheres were divided into several sections [4],[5],[6],[7]. Regional uptake was calculated in each sector and compared with corresponding sector of opposite hemisphere. [Figure - 2] shows a series of images consisting of plain and contrast enhanced CT images and the nuclear brain SPECT with region of interest placed around the lesion for quantification.


   Results Top


Twenty seven patients with ring enhancing lesions in the brain in CT and or MRI with different clinical conditions were tabulated together with the quantitative findings in the Nuclear imaging studies. A lesion to non-lesion ratio was also calculated for this study. The chart of all such cases is given below mentioning CT / MRI findings, the radiotracer, the clinical feature and the nuclear scan findings. A lesion to non-lesion ratio of 3 and above was found to be consistent with aggressive malignant lesions in most cases. Though biopsies could not be obtained in all cases, patients were and are being followed up till December, 2001.

The clinical behaviour of the patients who did not show very high uptake of radiotracer (lesion to non-lesion ratio < 3) are consistent with our results. Most of them have either improved or not shown any further sign of deterioration. Most of the patients who had very high uptake have either died or lost to follow up.

All the patients were the subjected to Nuclear imaging by a Gamma Camera (Siemens Diacom SPECT System) which included cerebral first pass study (CBF), planar and SPECT images obtained using different radiotracers like 99m Tc - HMPAO, TI - 201, 99m Tc - DTPA / GHA etc.

Intravenous injections of the radiotracer were given to the patients. Then the entire information was tabulated and quantitative studies of the lesions were done by Nuclear imaging methods.

Computerised quantifications of the regional radiotracer uptake in the lesions were performed. Symmetric ROIs (Region of interest) were drawn around the lesions. Mirror ROIs of same size were placed on the similar area of the opposite cerebral hemispheres. Reference background ROIs are also placed on normal regions. Lesion to non-lesion ratios were calculated from the above mentioned ROIs after pixel normalization. In another method each cerebral hemispheres was divided into several sections [4],[5],[6],[7]. Regional uptakes were calculated in each sector and compared with corresponding sector of opposite hemisphere. The [Figure - 2] shows a series of images consisting of plain and contrast enhanced CT images and the nuclear brain SPECT with region of interest placed around the lesion for quantifications.

[TAG:2]Discussion[/TAG:2]

Nuclear imaging specially with Brain SPECT studies is fast gaining great importance in distinguishing between neoplastic and non-neoplastic conditions by non-invasive techniques. Kim et al in Seoul National University College of medicine, South Korea studied 12 patients with ring enhancing lesions which showed differentiation between tumor and abscess using 99m Tc - HMPAO - WBC SPECT [2]

In our study, quantifications of the lesions by Nuclear imaging was vital in distinguishing neoplasm from non-neoplastic conditions and the lesion to non-lesion ratio based on certain calculations which determined these factors. Certain radiotracers have great affinity for tumours, especially for malignant tumours. Thallium - 201 Chloride, 99 m Tc - MIBI (sestanibi) and 99m Tc - Tetrofosmin are most important among them. All these radiotracers were primarily developed as myocardial imaging agents and their principal use in clinical nuclear medicine is for assessment of myocardial perfusion. However, it was found later on that these radiotracers are tumour-avid agents. Their concentrations in tumours were found to be proportional with the aggressiveness and viability of the neoplasm. They were found to be very helpful in differentiating recurrent tumour from post-operative or post-radiotherapy reactive changes [3],[4],[5],[6],[7],[8],[9].

99 Tc - DTPA and GHA are the other two groups of radiotracers which were also used in this study. They can get localized within a lesion inside the brain if the Blood Brain Barrier is disrupted and in our study the degree of uptake was found to be proportional with the aggressiveness of the tumours. 99m Tc - HMPAO is the brain perfusion agent which can cross intact blood brain barrier. It's main application is for demonstration of tumour vascularity [10],[14].

The size, shape and wall thickness of the ring enhancing lesions in CT and or MRI with the extent of surrounding oedema often helps to distinguish the kind of condition provided the clinical history and age of the patient was taken into consideration. Eccentric or centrally enhancing mural nodules in small ring enhancing lesions help to demarcate a granuloma from any other benign or inflammatory condition. MR findings in case of an abscess will vary with time. Anaplastic astrocytoma shows an irregular ring enhancement commonly in C T, while in MR there is marked contrast enhancement but an irregular rim enhancement is usually noted. MRI of course demonstrates demyelinating plaques much better than any other imaging modality and following contrast the diagnosis makes little difference except for the number of demonstrable lesions. Without the clinical history ring enhancing lesions in the brain in CT and/ or MRI quite often than not may be confusing between a neoplastic and non-neoplastic condition, in which MR Spectroscopy or CT / MRI guided Stereotatic biopsies are required for further evaluation and confirmation. The best non-invasive method would be a Brain SPECT or PET study. Yoshie Y, Moritate T and et al from Dept. of Neuro-surgery. University of Tsukuba, Japan studied histological features and degree of TI-uptake in patients with glial and non-glial tumours. The study showed that early uptake indicates degree of necrosis of glial tumour. Delayed uptake indicates Tumour cell density and Small cell density. In Non-glial tumors, Degree of necrosis and vascularisation are related to high uptake [13],[15].

Tomura N. Hirano et al from Akita University School of Medicine. Japan studied several cases with MIBI and their index showed that lesion: non lesion ratio more than 6-7 to be indicative of a malignant lesion [11]. Another study done by Lorberboym M. Baran J et al from Sheba Medical Centre, Israel showed T1-201 SPECT is more reliable than CT / MRI in identifying progression, improvement or no-change in brain tumour [12].

Amongst the different radiotracers used TI-201 and 99 mTc - MIBI or Tetrofosmin are found to be more specific for tumours, more so for malignant neoplasms. 99 mTc - HMPAO is not principally used for tumour imaging though being a perfusion agent which can cross the intact blood brain barrier, it can give an idea regarding the vascularity of the lesions. However, in combination with TI-201 it is found to be very useful in distinguishing post-radiotherapy changes in a neoplasm from recurrence of tumour. 99 mTc - DTPA and gHA cannot cross an intact blood brain barrier.

To conclude, Nuclear scanning was helpful in distinguishing between neoplastic and non-neoplastic conditions in 42% of cases in this study where CT or MRI were doubtful. The neoplastic lesions could be quantified in terms of their aggressiveness by Nuclear imaging in circumstances where MR spectroscopy is absent or inconclusive. Further evaluation as well as correlative studies with PET, Stereotactic biopsies and post-operative / post mortem histopathological findings are needed

 
   References Top

1.Osbom AG. Infection of the brain and its lining. Diagnostic Neuroradiology. Mosby 1994: 673-715.  Back to cited text no. 1    
2.KIM DG; Lee JI; Lee MC; Choi K S; Han DH. 99m MIBI brain brain SPECT of cerebellopontine angle tumours. Clin Nucl. Med. 1996. 21(5):375-8.  Back to cited text no. 2    
3.Abdel - Dayem HM. Thallium - 201 Chloride - A tumor imaging agent. Murrary PC. Nuclear medicine in clinical diagnosis and treatment, 2nd Edition. Churchill Livingstone 1999: 831-841.  Back to cited text no. 3    
4.Datz FL, Morton KA: New radiopharmaceuticals for detecting infection, Invest Radiol 1993; 28: 356 - 366.  Back to cited text no. 4    
5.Hirano T; et al Tc-99m (V) - DMSA and thallium - 201 in brain tumour imaging: correlation with histology and malignant grade. J Nucl Med. 1997. 38 (11): 1741-9.  Back to cited text no. 5    
6.Park C H; Sataloff R; Richard M: Zhang J; Kim S M, Tc - 99 m MIBI brain SPECT of cerebellopontine angle tumours. Clin Nucl med. 1996. 21 (5): 375-8.  Back to cited text no. 6    
7.Weber; et al . Flourine 18-FDG PET and iodine - 123 IMT SPECT in the evaluation of brain tumours. J Nucl. Med 1997. 38 (5): 802 - 8.  Back to cited text no. 7    
8.Togawa T, et al . A study on thallium - 201 SPECT in brain metastases of lung cancer: with special reference to tumour size and tumour to normal brain thallium uptake ratio, Kaku lgaku 1995. 32(3): 217-25.  Back to cited text no. 8    
9.Diaz-Vicenta J. et. al. the use of SPECT with 201 TI in the evaluation of brain tumours, rev. Neurol. 1995: 24 (132): 909.  Back to cited text no. 9    
10.KIM DG; Lee JI; Lee DS; Lee MC; Choi KS; Han DH, 99m Tc-HMPAO labeled leukocyte SPECT in intracranial lesions, Surg Neurol. 1995. 44 (4): 338 - 45.  Back to cited text no. 10    
11.Tomura N. et al . Preliminary results with technetium - 99m M 181 SPECT imaging in patients with brain tumours: correlation with histological and neuroradiological diagnoses and therapeutic response. Comput. Med Imaging Graph. 1997: 21 (5): 293-8.  Back to cited text no. 11    
12.Lorberboym M. et al . A prospective evaluation of thallium - 201 single photon emission computerized tomography of brain tumour burden. Int. J Radiant Oncol Biol Phys. 1995 32 (1): 249 - 54.  Back to cited text no. 12    
13.Yoshi Y, et al Correlation of histopathological factor of brain tumour and high thallium - 201 uptake in single photon emission computed tomography. Noshuyo Byori. 1996. 13 (1): 61-5.  Back to cited text no. 13    
14.Grimstad IA, Hirschberg H. Rootwell K - 99m Tc - hexamethyl propyleneamine oxime leukocyte scintigraphy and C-ractive protein levels in the differential diagnosis of brain abscesses. Neuro surg 1992; 77: 732 - 736.  Back to cited text no. 14    
15.Kine J L; Noto RBI; Glantz M - Single - photon emission CT in the evaluation of recurrent brain tumour in patients treated with gamma knife rediosurgery or conventional radiation therapy. AJNR Am neuroradiol 1996. 17(9): 1681 - 6  Back to cited text no. 15    

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Correspondence Address:
S Ray
EKO X-ray & Imaging Institute, 54, Jawaharlal Nehru Road, Calcutta-700071
India
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Source of Support: None, Conflict of Interest: None


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    Figures

[Figure - 1], [Figure - 2], [Figure - 3]

    Tables

[Table - 1]

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