Toxoplasmosis and primary central nervous system lymphoma in HIV infection: diagnosis with MR spectroscopy

HIV-1-infected patients with focal neurologic signs: diagnostic role of PCR for Toxoplasma gondii, Epstein-Barr virus, and JC virus

OBJECTIVE: To evaluate nested PCR for Toxoplasma gondii (TOX), JC virus (JCV) and Epstein-Barr virus (EBV) for diagnosis of toxoplasmic encephalitis (TE), progressive multifocal leukencephalopathy (PML) and primary central nervous system lymphoma (PCL). METHODS: A prospective study encompassed 26 HIV-1-infected individuals presenting with focal neurologic signs and symptoms. Nested PCR was performed on both supernatants and pellets of centrifuged cerebrospinal fluid (CSF), on plasma and on white blood cells (WBCs). For a retrospective study, stored CSF supernatants were available from an additional 27 HIV-1-infected patients with TE, PML, and PCL. RESULTS: TE, PML or PCL was diagnosed in 13 of 26 patients in the prospective group. Plasma and WBC analysis by PCR was not informative except in one case of TE. TOX and JCV were detected by PCR in the CSF pellets of four of five patients with TE, and of four of five patients with PML, respectively, but in no other cases. EBV was detected not only in three of three cases of PCL, but also in six patients suffering from other conditions. PCR on the CSF supernatants was less sensitive for all three etiologies. These results correlated with those of the retrospective PCR analysis, for which only stored CSF supernatants were available, revealing sensitivities of 33%, 50% and 66% for TE, PML and PCL, respectively, but specificities of 100%. CONCLUSIONS: In the clinical routine, TOX and JCV PCR on centrifuged CSF pellets can be recommended to obtain an early diagnosis of TE and PML. Under these conditions, EBV PCR helps to exclude PCL as a cause of FBLs, as it is highly sensitive, but not specific, for PCL in HIV-1-infected individuals.

Spectroscopic increase in choline signal is a nonspecific marker for differentiation of infective/inflammatory from neoplastic lesions of the brain

We report in vivo proton magnetic resonance (MR) spectroscopic findings in three benign infective/inflammatory lesions (one case each of tuberculoma, fungal granuloma, and xanthogranuloma), which showed high choline along with the presence of lipid/lactate, a feature characteristically described in neoplastic lesions. Histopathology of the lesions showed inflammatory cellular infiltrates with areas of necrosis/caseation. The spectroscopic-visible increased choline resonance in these lesions is probably the result of cellularity. We conclude that increased choline, along with the presence of lipid/lactate is a nonspecific finding and may not be of much value in the differentiation of neoplastic from nonneoplastic infective/inflammatory intracranial mass lesions.

Endovascular Surgery for Internal Carotid Stenoses. Results of PTA vs. Stenting

SUMMARY

This paper will overview our results of endovascular therapy (PTA or stenting) for cervical ICA stenosis and discuss the advantages and disadvantages of each treatment. 60 cases with 62 lesions were treated with PTA 68 times, while 36 cases with 37 lesions were treated with stenting 37 times. A total of 99 lesions were treated with PTA or stenting 105 times. In the PTA group arterial stenosis improved from 76.4% to 21%. In the stent group the stenosis improved from 82.3% to 8.3%. The morbidity rate was 2/60 (3.3%) in PTA group, although two cases had minor neurological deficits, while in stent treated group, morbidity rate was 1/36 (2.8%), although it showed one major neurological deficit. Mortality was 0% in each group. The restenosis rate in PTA group was 15/58 (26%), while it was 0/20 (0%) in stent treated group. Stenting brings significant reduction of stenosis and reduces the rate of restenosis compared to PTA. However, stenting has its own disadvantages such as hypotension and distal kinks when deployed in tortuous ICA stenosis.

SPECT thallium-201 combined with Toxoplasma serology for the presumptive diagnosis of focal central nervous system mass lesions in patients with AIDS

OBJECTIVE

To determine the utility of brain thallium-201 single photon emission computerized tomography (Tl-201 SPECT) combined with Toxoplasma serology for the diagnosis of focal CNS lesions in patients with AIDS.

METHODS

Sixty-one consecutive HIV-infected patients with focal CNS lesion(s) on head computed tomography (CT) or MRI scan who underwent brain Tl-201 SPECT and serum Toxoplasma serology were evaluated, retrospectively. Thallium-201 uptake ratios were calculated by comparing lesion activity to contralateral scalp activity. Diagnoses were made by a combination of histology, serology, PCR, and empirical response to therapy. Toxoplasma serologies (IgG IFA) were compared in the patients with central nervous system (CNS) toxoplasmosis and those without CNS toxoplasmosis.

RESULTS

Fifty-six patients were evaluable and a definitive diagnosis was made in 38 patients: toxoplasmosis (17), lymphoma (14), PML (three), Aspergillus (one), tuberculoma (one), Cryptococcus (one), varicella-zoster virus (one). Patients with lymphoma had significantly higher lesion/contralateral scalp ratios compared to patients without lymphoma: 1.03 vs. 0.67, P < 0.05. Using a cut-off of 0.90 for the lesion/scalp uptake ratios (based on analysis of ROC curves) the sensitivity and specificity for the diagnosis of lymphoma were 86% and 83%, respectively. Serum Toxoplasma IgG titres were significantly higher in patients diagnosed with toxoplasmosis compared to those with a diagnosis other than toxoplasmosis, 1:5444 vs. 1:15, P < 0.05. Only one patient with confirmed toxoplasmosis had a Toxoplasma serology < 1:256, while no patients without toxoplasmosis (including all lymphoma patients) had serologies > 1:256.

CONCLUSIONS

In a series of HIV-infected patients, Tl-201 SPECT was able to accurately differentiate primary brain lymphoma from other causes of focal CNS lesions in most patients; however, both false positive and false negative results occurred. By combining Tl-201 SPECT with serum Toxoplasma IgG, diagnostic accuracy was improved.

Localised 1H-MR spectroscopy for metabolic characterisation of diffuse and focal brain lesions in patients infected with HIV

OBJECTIVES

To evaluate the role of proton MR spectroscopy (1H-MRS) in detecting metabolic changes in diffuse or focal lesions in the brain of patients infected with HIV.

METHODS

Sixty HIV seropositive patients (25 with HIV related encephalopathies, 20 with toxoplasmosis, eight with progressive multifocal leukoencephalopathies (PMLs), and seven with lymphomas) and 22 HIV seronegative neurological controls were examined with a combined MRI and 1H-MRS technique using a Siemens 1.5 Tesla Magnetom. Spectra (Spin Echo sequence, TE 135 ms) were acquired by single voxel, localised on focal lesions in toxoplasmosis, PML, lymphomas, and HIV encephalopathies and on the centrum semiovale of neurological controls. Choline (Cho), creatine (Cr), N-acetyl aspartate (NAA), lactate, and lipids were evaluated in each spectrum and NAA/Cr, NAA/Cho, and Cho/Cr ratios were calculated.

RESULTS

A significant decrease in NAA/Cr and NAA/Cho ratios were found in all HIV diagnostic groups in comparison with neurological controls (p<0.003), suggesting neuronal or axonal damage independent of brain lesion aetiology. However, the NAA/Cr ratio was significantly lower in PML and lymphomas than in HIV encephalopathies (p<0.02) and toxoplasmosis (p<0.05). HIV encephalopathies, lymphomas, and toxoplasmosis showed a significant increase in the Cho/Cr ratio in comparison with neurological controls (p<0.03) without between group differences. The presence of a lipid signal was more frequent in lymphomas (71%) than in other HIV groups (Fisher's test, p=0.00003). The presence of mobile lipid resonance together with a high Cho/Cr ratio in lymphomas may be related to an increased membrane synthesis and turnover in tumour cells. A lactate signal (marker of inflammatory reaction), was found in all but one patient with PML lesions (75%), but had a lower incidence in the other HIV diagnostic groups (Fisher's test, p=0.00024).

CONCLUSION

1H-MRS shows a high sensitivity in detecting brain involvement in HIV related diseases, but a poor specificity in differential diagnosis of HIV brain lesions. Nevertheless, the homogeneous metabolic pattern that characterises PML suggests the usefulness of 1H-MRS as an adjunct to MRI in differentiating CNS white matter lesions, such as HIV encephalopathies, from PML.